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RSS2016 Vol. 28, No. 06
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2016,
28: 064101.
doi: 10.11884/HPLPB201628.064101
Abstract:
In order to analyze sensing mechanisms of bulk acoustic wave(BAW) force sensors based on the stress/strain effects and calculate their sensitivity accurately, a calculus-like analysis method is proposed. Drawing on the principles of calculus, the method replaces a full BAW resonator with numerous parallel resonator infinitesimals in the Mason equivalent circuit model. Thus, the finite element method(FEM) simulated stress/strain field across the BAW resonators active area can be associated with the mechanical characteristics of its piezoelectric film and electro-acoustic characteristics of its infinitesimals. Finally, the equivalent circuit is integrated in RF circuit simulation software to get the impedance characteristic curve and the series/parallel resonant frequency of the BAW resonator with an applied stress/strain field. When the resonator infinitesimals are sliced tiny enough, sensitivity analysis results will be accurate enough. Instanced with an embedded-FBAR quad-beam BAW accelerometer sensor-head, detailed application procedure of the method is introduced. Although only a single force sensing mechanism in a single stress/strain type BAW sensor is discussed in this case, the presented method is quite general. When the resonator infinitesimals are more close to the scale of crystal lattice of the piezoelectric material, the method might bridge the analysis with the first-principle calculated mechanic-acoustic-electronic characteristics of the piezoelectric film, enabling a multi-scale calculation from the microscopic materials characteristics to the mesoscopic devices physics.
In order to analyze sensing mechanisms of bulk acoustic wave(BAW) force sensors based on the stress/strain effects and calculate their sensitivity accurately, a calculus-like analysis method is proposed. Drawing on the principles of calculus, the method replaces a full BAW resonator with numerous parallel resonator infinitesimals in the Mason equivalent circuit model. Thus, the finite element method(FEM) simulated stress/strain field across the BAW resonators active area can be associated with the mechanical characteristics of its piezoelectric film and electro-acoustic characteristics of its infinitesimals. Finally, the equivalent circuit is integrated in RF circuit simulation software to get the impedance characteristic curve and the series/parallel resonant frequency of the BAW resonator with an applied stress/strain field. When the resonator infinitesimals are sliced tiny enough, sensitivity analysis results will be accurate enough. Instanced with an embedded-FBAR quad-beam BAW accelerometer sensor-head, detailed application procedure of the method is introduced. Although only a single force sensing mechanism in a single stress/strain type BAW sensor is discussed in this case, the presented method is quite general. When the resonator infinitesimals are more close to the scale of crystal lattice of the piezoelectric material, the method might bridge the analysis with the first-principle calculated mechanic-acoustic-electronic characteristics of the piezoelectric film, enabling a multi-scale calculation from the microscopic materials characteristics to the mesoscopic devices physics.
2016,
28: 064102.
doi: 10.11884/HPLPB201628.064102
Abstract:
SU-8 thick resist lithography has become the mainstream technology for structures with high aspect ratio in the micro-electro-mechanical system (MEMS) and integrated circuits (ICs). So as to replace expensive and time-consuming lithographic experiments, lithography simulation becomes an increasingly valuable tool for predicting results and optimizing manufacture process. A three-dimensional (3D) lithography simulation model is developed for the ultraviolet (UV) process of SU-8 resist. The model utilizes waveguide (WG) method based on rigorous electromagnetic field theory, which is more comprehensive than its two-dimension counterparts. Using this model, the light intensity distribution and morphology of photoresist after development process can be stereoscopically predicted. A series of simulations and experiments have been conducted to verify the validity of the model. The study is carried out on SU-8 under UV source with 365 nm and 2.6 mW/cm2. Simulation results are given by cross section image and stereogram combined with corresponding experimental outcome. The results confirm the validity of the simulation model and prove that the 3D hybrid model is faster than other methods and remains accurate.
SU-8 thick resist lithography has become the mainstream technology for structures with high aspect ratio in the micro-electro-mechanical system (MEMS) and integrated circuits (ICs). So as to replace expensive and time-consuming lithographic experiments, lithography simulation becomes an increasingly valuable tool for predicting results and optimizing manufacture process. A three-dimensional (3D) lithography simulation model is developed for the ultraviolet (UV) process of SU-8 resist. The model utilizes waveguide (WG) method based on rigorous electromagnetic field theory, which is more comprehensive than its two-dimension counterparts. Using this model, the light intensity distribution and morphology of photoresist after development process can be stereoscopically predicted. A series of simulations and experiments have been conducted to verify the validity of the model. The study is carried out on SU-8 under UV source with 365 nm and 2.6 mW/cm2. Simulation results are given by cross section image and stereogram combined with corresponding experimental outcome. The results confirm the validity of the simulation model and prove that the 3D hybrid model is faster than other methods and remains accurate.
2016,
28: 064103.
doi: 10.11884/HPLPB201628.064103
Abstract:
In this paper, MEMS vector hydrophone is proposed to apply in submerged buoy system, and a large number of experiments are done to verify its feasibility. The MEMS vector hydrophone, a kind of underwater acoustic sensor, has lots of advantages, such as small size, low cost, better consistency and high sensitivity. When applied in submerged buoy system, it can sharply reduce the array aperture and can effectively detect the vector information of the marine sound field. Mainly, it can obtain good spatial gain and solve the problem of bulky volume of sonar equipment when applied in the field of low and very low frequency. The prototype of the submerged buoy system has undergone a number of indoor debugging and outdoor tests. After the preliminary treatment of the trial data, the results show that this system can effectively detect the acoustic field vector signal in range of 20-1000 kHz under ocean. The MEMS vector hydrophone sensitivity can reach －176 dB and has a good 8 shaped directivity pattern.
In this paper, MEMS vector hydrophone is proposed to apply in submerged buoy system, and a large number of experiments are done to verify its feasibility. The MEMS vector hydrophone, a kind of underwater acoustic sensor, has lots of advantages, such as small size, low cost, better consistency and high sensitivity. When applied in submerged buoy system, it can sharply reduce the array aperture and can effectively detect the vector information of the marine sound field. Mainly, it can obtain good spatial gain and solve the problem of bulky volume of sonar equipment when applied in the field of low and very low frequency. The prototype of the submerged buoy system has undergone a number of indoor debugging and outdoor tests. After the preliminary treatment of the trial data, the results show that this system can effectively detect the acoustic field vector signal in range of 20-1000 kHz under ocean. The MEMS vector hydrophone sensitivity can reach －176 dB and has a good 8 shaped directivity pattern.
2016,
28: 064104.
doi: 10.11884/HPLPB201628.064104
Abstract:
In order to remove the undesired DC offset of integral signal, a modified integral algorithm based on the Single Moving Average Method is proposed. In this algorithm, the N samples during one cycle are collected as a set, and the average value of them is calculated as the instantaneous DC offset. Therefore, a pure AC signal without any offset is obtained by subtracting the DC offset from the integral signal. On every rising edge of the clock, a new sampling point is added into the set and the oldest one should be removed. In this way, the length of the set remains constant and the DC offset can be updated in real time. Both the simulation and test results demonstrate the effectiveness of this integral algorithm. This algorithm has been successfully used in the sliding mode controller of a MEMS gyroscope. Compared with the existing integral algorithm, the proposed method is less complex, easier to be realized and can achieve better real time response.
In order to remove the undesired DC offset of integral signal, a modified integral algorithm based on the Single Moving Average Method is proposed. In this algorithm, the N samples during one cycle are collected as a set, and the average value of them is calculated as the instantaneous DC offset. Therefore, a pure AC signal without any offset is obtained by subtracting the DC offset from the integral signal. On every rising edge of the clock, a new sampling point is added into the set and the oldest one should be removed. In this way, the length of the set remains constant and the DC offset can be updated in real time. Both the simulation and test results demonstrate the effectiveness of this integral algorithm. This algorithm has been successfully used in the sliding mode controller of a MEMS gyroscope. Compared with the existing integral algorithm, the proposed method is less complex, easier to be realized and can achieve better real time response.
2016,
28: 064105.
doi: 10.11884/HPLPB201628.064105
Abstract:
To achieve intellectualization and miniaturization of fuze, a novel high-g dual-threshold MEMS (Micro-Electro-Mechanical Systems) inertial switch has been designed and simulated under the premise of ensuring its service safety and launching reliability. The MEMS inertial switch consists of two modules named recognition module M1 and energized module M2 respectively. It can recognize two typical loads (load 1: 15 000g-300 ms, load 2: 3000g-3 ms) by taking advantage of collisions between a mass and two baffles without power consumption. Planar Z-shaped tooth on the mass and two baffles are significant to recognize these two different loads and their parameters have been studied. Dynamic simulations have been taken to optimize the design. Corresponding simulation results show that when load 1 is applied on the switch in the sensing direction, it keeps disconnected, while load 2 is applied in the same direction, it is closed.
To achieve intellectualization and miniaturization of fuze, a novel high-g dual-threshold MEMS (Micro-Electro-Mechanical Systems) inertial switch has been designed and simulated under the premise of ensuring its service safety and launching reliability. The MEMS inertial switch consists of two modules named recognition module M1 and energized module M2 respectively. It can recognize two typical loads (load 1: 15 000g-300 ms, load 2: 3000g-3 ms) by taking advantage of collisions between a mass and two baffles without power consumption. Planar Z-shaped tooth on the mass and two baffles are significant to recognize these two different loads and their parameters have been studied. Dynamic simulations have been taken to optimize the design. Corresponding simulation results show that when load 1 is applied on the switch in the sensing direction, it keeps disconnected, while load 2 is applied in the same direction, it is closed.
2016,
28: 064106.
doi: 10.11884/HPLPB201628.064106
Abstract:
The micro-opto-electro-mechanical systems (MOEMS) mirror is an important optical device in laser display, light beam scanning, and adaptive optics applications. MOEMS mirrors are mostly attractive electrostatically actuated in the reported literatures, which are troubled by the pull-in effect. Additionally, the mismatch of square actuators and circular mirror will make the fill factor much lower. A MOEMS mirror based on electrostatic repulsive circular actuator and surface fabrication process is proposed in this paper. Arranged like a ring around, the actuator matches well with the circular mirror. The designed MOEMS mirror has an aperture of 204 m, and is fabricated by polycrystalline silicon multi-users-MEMS-processes (PolyMUMPs) process. Simulation and experimental results show that the mirror has a maximum rotation angle of 0.62, a response time of 494 s and an operation bandwidth of 1.191 kHz, and is suitable for the common beam scanning applications.
The micro-opto-electro-mechanical systems (MOEMS) mirror is an important optical device in laser display, light beam scanning, and adaptive optics applications. MOEMS mirrors are mostly attractive electrostatically actuated in the reported literatures, which are troubled by the pull-in effect. Additionally, the mismatch of square actuators and circular mirror will make the fill factor much lower. A MOEMS mirror based on electrostatic repulsive circular actuator and surface fabrication process is proposed in this paper. Arranged like a ring around, the actuator matches well with the circular mirror. The designed MOEMS mirror has an aperture of 204 m, and is fabricated by polycrystalline silicon multi-users-MEMS-processes (PolyMUMPs) process. Simulation and experimental results show that the mirror has a maximum rotation angle of 0.62, a response time of 494 s and an operation bandwidth of 1.191 kHz, and is suitable for the common beam scanning applications.
2016,
28: 064107.
doi: 10.11884/HPLPB201628.064107
Abstract:
By scanning electrochemical microscopy ( SECM ) and traditional electrochemical method, the effect of loading potential variation on direct methanol fuel cell ( DMFC ) anode performance was studied. When the anode was loaded for 2 h at different potential, the number of peak current reduced with loading potential increasing while the corresponding peak current value increased first and then decreased, which manifested that the anodes catalytic distributed rather differently and reduced with loaded time and potential. The forward and the reverse sweep current peaks in cyclic voltammetry also first moved to negative and then shifted to positive with loaded time increasing while its resistance ability to CO continuously decreased. After loaded for 16 h and 72 h at 0.6 V, the average size of catalysts changed from 3.4 nm to 3.6 nm and 4.4 nm, respectively. While loaded for 72 h at 0.8 V, the weight ratio of Pt/Ru in catalyst changed from 2.0 to 3.9. Changing loaded potential exacerbated the uneven distribution of catalytic site, catalyst particle enlargement and Ru lose, which contributed to the catalytic activity deterioration.
By scanning electrochemical microscopy ( SECM ) and traditional electrochemical method, the effect of loading potential variation on direct methanol fuel cell ( DMFC ) anode performance was studied. When the anode was loaded for 2 h at different potential, the number of peak current reduced with loading potential increasing while the corresponding peak current value increased first and then decreased, which manifested that the anodes catalytic distributed rather differently and reduced with loaded time and potential. The forward and the reverse sweep current peaks in cyclic voltammetry also first moved to negative and then shifted to positive with loaded time increasing while its resistance ability to CO continuously decreased. After loaded for 16 h and 72 h at 0.6 V, the average size of catalysts changed from 3.4 nm to 3.6 nm and 4.4 nm, respectively. While loaded for 72 h at 0.8 V, the weight ratio of Pt/Ru in catalyst changed from 2.0 to 3.9. Changing loaded potential exacerbated the uneven distribution of catalytic site, catalyst particle enlargement and Ru lose, which contributed to the catalytic activity deterioration.
2016,
28: 064108.
doi: 10.11884/HPLPB201628.064108
Abstract:
The self-heating effect of the capacitive RF MEMS switch is caused by increasing incident power of the RF signal, which leads to deformation of the membrane. Thus, the air gap of the switch is changed. Eventually the drift of the actuation voltage of the switch is prompted, which seriously affect the reliability of the switch. Because the failure mechanisms of self-heating effect involves complex multi-physics coupling, the failure mechanisms are analysed and the failure modes are described by proposing the electromagnetic-thermo-mechanic multi-physics cooperative simulation method. Firstly, the dissipation power of the membrane under different incident power is got by constructing the electromagnetic simulation model of the switch in HFSS, which is taken as a heat source. Then the distribution of the surface temperature of the membrane is got by constructing the thermal simulation model of the switch in ePhysics, which is taken as a load. Next, the deformation behavior model of the switch is obtained by constructing the stress simulation model of the switch in ePhysics. At last, according to the change of the air gap caused by deformation, the failure prediction model of the drift of the actuation voltage is obtained. Taking a typical capacitive RF MEMS switch with rectangular membrane geometry for an instance, the distribution along the edge of the length of the surface current density of the membrane is got with this method. And the temperature gradually reduces along the edge of the length, with the highest temperature in the center and the lowest at the anchor. It is found that the maximum deformation point of the membrane appears on the edges of the long side. And the deformation presents a saddle surface. The linear relationship of the drift between the actuation voltage of the switch and the incident power (0-5 W) of the RF signal is fitted by getting maximum deformation value of the membrane under different temperature incident power (0-5 W). The effectiveness of the proposed method is proved by comparing with the measured data of the references.
The self-heating effect of the capacitive RF MEMS switch is caused by increasing incident power of the RF signal, which leads to deformation of the membrane. Thus, the air gap of the switch is changed. Eventually the drift of the actuation voltage of the switch is prompted, which seriously affect the reliability of the switch. Because the failure mechanisms of self-heating effect involves complex multi-physics coupling, the failure mechanisms are analysed and the failure modes are described by proposing the electromagnetic-thermo-mechanic multi-physics cooperative simulation method. Firstly, the dissipation power of the membrane under different incident power is got by constructing the electromagnetic simulation model of the switch in HFSS, which is taken as a heat source. Then the distribution of the surface temperature of the membrane is got by constructing the thermal simulation model of the switch in ePhysics, which is taken as a load. Next, the deformation behavior model of the switch is obtained by constructing the stress simulation model of the switch in ePhysics. At last, according to the change of the air gap caused by deformation, the failure prediction model of the drift of the actuation voltage is obtained. Taking a typical capacitive RF MEMS switch with rectangular membrane geometry for an instance, the distribution along the edge of the length of the surface current density of the membrane is got with this method. And the temperature gradually reduces along the edge of the length, with the highest temperature in the center and the lowest at the anchor. It is found that the maximum deformation point of the membrane appears on the edges of the long side. And the deformation presents a saddle surface. The linear relationship of the drift between the actuation voltage of the switch and the incident power (0-5 W) of the RF signal is fitted by getting maximum deformation value of the membrane under different temperature incident power (0-5 W). The effectiveness of the proposed method is proved by comparing with the measured data of the references.
2016,
28: 064109.
doi: 10.11884/HPLPB201628.064109
Abstract:
In this paper, the response surface methodology(RSM) is applied to optimizing the operating conditions of silicon etching for pressure sensor fabrication. Three operating parameters, the temperature, the KOH concentration and the etching time are considered in this study, and the ranges of them are 40-60℃, 0.4-0.48 mol/L and 5-12.5 h, respectively. A quadratic model is established to describe the anisotropic etching rate as the response value, and the individual effects of these operating parameters and the combined effects of multiple operating conditions on etching rate are examined.
In this paper, the response surface methodology(RSM) is applied to optimizing the operating conditions of silicon etching for pressure sensor fabrication. Three operating parameters, the temperature, the KOH concentration and the etching time are considered in this study, and the ranges of them are 40-60℃, 0.4-0.48 mol/L and 5-12.5 h, respectively. A quadratic model is established to describe the anisotropic etching rate as the response value, and the individual effects of these operating parameters and the combined effects of multiple operating conditions on etching rate are examined.
2016,
28: 064110.
doi: 10.11884/HPLPB201628.064110
Abstract:
An endoscope system and its corresponding image analysis methods are proposed to implement the assembly quality control of a kind of Interferometric Fiber Optic Gyroscope (IFOG). Two industrial endoscopes with diameter of 1mm and 2.4 mm are utilized to capture the inner images and the video of IFOG. A movement control platform is used to tune the attitude of endoscope system. Some image enhancement methods and image feature analysis techniques, such as the db4 wavelet enhancement technique, the Gray Level Co-occurrence Matrix (GLCM) feature analysis method and the geometry shape features, etc. are all employed to improve the imaging output quality of endoscope system. By using the proposed endoscope system, some assembly quality problems such as the remainder particles, the broken fibers, or the improper gluing, etc. can all be observed and identified conveniently.
An endoscope system and its corresponding image analysis methods are proposed to implement the assembly quality control of a kind of Interferometric Fiber Optic Gyroscope (IFOG). Two industrial endoscopes with diameter of 1mm and 2.4 mm are utilized to capture the inner images and the video of IFOG. A movement control platform is used to tune the attitude of endoscope system. Some image enhancement methods and image feature analysis techniques, such as the db4 wavelet enhancement technique, the Gray Level Co-occurrence Matrix (GLCM) feature analysis method and the geometry shape features, etc. are all employed to improve the imaging output quality of endoscope system. By using the proposed endoscope system, some assembly quality problems such as the remainder particles, the broken fibers, or the improper gluing, etc. can all be observed and identified conveniently.
2016,
28: 064111.
doi: 10.11884/HPLPB201628.064111
Abstract:
The electroforming microfluidic chip mould faces the problem of uneven thickness,which influences the dimensional accuracy and performance of the mould, and increases the production cost. With the aim of fabricating a microfluidic chip mould with uniform thickness, electroforming with ultrasonic agitation is investigated to improve the thickness uniformity of the mould. Firstly, numerical simulation is performed using COMSOL multiphysics software to analyze the thickness distribution of the mould after 2 h electroforming. And based on the simulation result, a photomask is designed. Secondly, with the photomask, electroforming experiments are carried out to study how ultrasonic agitation affects the thickness uniformity of the mould. It is found that the ultrasonic agitation can improve the thickness uniformity of the mould. With 200 W ultrasonic agitation, the effect of ultrasonic frequency on the thickness uniformity increases in the order of 200 kHz＞80 kHz＞120 kHz. And with 200 kHz ultrasonic agitation, the effect of ultrasonic power on the thickness uniformity increases in the order of 500 W＞200 W＞100 W. Compared with the thickness uniformity without ultrasonic agitation, with 200 kHz and 500 W ultrasonic agitation, the thickness uniformity of the mould is increased by about 30%.
The electroforming microfluidic chip mould faces the problem of uneven thickness,which influences the dimensional accuracy and performance of the mould, and increases the production cost. With the aim of fabricating a microfluidic chip mould with uniform thickness, electroforming with ultrasonic agitation is investigated to improve the thickness uniformity of the mould. Firstly, numerical simulation is performed using COMSOL multiphysics software to analyze the thickness distribution of the mould after 2 h electroforming. And based on the simulation result, a photomask is designed. Secondly, with the photomask, electroforming experiments are carried out to study how ultrasonic agitation affects the thickness uniformity of the mould. It is found that the ultrasonic agitation can improve the thickness uniformity of the mould. With 200 W ultrasonic agitation, the effect of ultrasonic frequency on the thickness uniformity increases in the order of 200 kHz＞80 kHz＞120 kHz. And with 200 kHz ultrasonic agitation, the effect of ultrasonic power on the thickness uniformity increases in the order of 500 W＞200 W＞100 W. Compared with the thickness uniformity without ultrasonic agitation, with 200 kHz and 500 W ultrasonic agitation, the thickness uniformity of the mould is increased by about 30%.
2016,
28: 064113.
doi: 10.11884/HPLPB201628.064113
Abstract:
Pressure resistance is an essential characteristic of microspheres which has applications in various fields but the manual measurement of it is laborious and inaccurate. The method of automatic measurement using image detection to discriminate microspheres failures is proposed. Gradient Hough transform is used to localize microspheres. Contours are extracted via Canny edge detection and environment disturbances are also alleviated; finally Hu invariant moments are employed to implement image matching. A customized experiment platform was established and experiments involving glass and polymer microspheres with different diameters were conducted to examine the accuracy and robustness of the method. Nearly 100% success rate for discrimination of failed microspheres was achieved and the pressures at which microspheres failed were recorded with little delay.
Pressure resistance is an essential characteristic of microspheres which has applications in various fields but the manual measurement of it is laborious and inaccurate. The method of automatic measurement using image detection to discriminate microspheres failures is proposed. Gradient Hough transform is used to localize microspheres. Contours are extracted via Canny edge detection and environment disturbances are also alleviated; finally Hu invariant moments are employed to implement image matching. A customized experiment platform was established and experiments involving glass and polymer microspheres with different diameters were conducted to examine the accuracy and robustness of the method. Nearly 100% success rate for discrimination of failed microspheres was achieved and the pressures at which microspheres failed were recorded with little delay.
2016,
28: 064114.
doi: 10.11884/HPLPB201628.064114
Abstract:
In this paper, we present a simplified calibration and compensation method that enables the piezoresistive pressure sensor to function with high resolution in wide range of ambient temperature. Normally, extensive work in calibration and compensation of atmosphere piezoresistive pressure sensors is always requested. In order to simplify the calibration and compensation method, the sensors structure is studied through incorporating heating resistors with a MEMS chip. It was placed on a PCB board with heating resistors. The MEMS chip was kept at a constant temperature state by dynamically modulating the on-and-off time of the heating resistors with a PID algorithm in MCU. After the calibration the constant temperature will not vary with the variation of ambient temperature, which enables the sensor to function in a wide range of ambient temperature. The results suggest that the designed sensor is a good choice for measurement of atmosphere pressure.
In this paper, we present a simplified calibration and compensation method that enables the piezoresistive pressure sensor to function with high resolution in wide range of ambient temperature. Normally, extensive work in calibration and compensation of atmosphere piezoresistive pressure sensors is always requested. In order to simplify the calibration and compensation method, the sensors structure is studied through incorporating heating resistors with a MEMS chip. It was placed on a PCB board with heating resistors. The MEMS chip was kept at a constant temperature state by dynamically modulating the on-and-off time of the heating resistors with a PID algorithm in MCU. After the calibration the constant temperature will not vary with the variation of ambient temperature, which enables the sensor to function in a wide range of ambient temperature. The results suggest that the designed sensor is a good choice for measurement of atmosphere pressure.
2016,
28: 064115.
doi: 10.11884/HPLPB201628.064115
Abstract:
A multifunction sensor based on nano-polysilicon thin film resistors which consists of pressure sensor and acceleration sensor is described. The two Wheatstone bridges consisting of piezoresistors are designed on the surface of square silicon membrane and the root of cantilever beam, respectively. The chips of pressure and acceleration sensors are fabricated on silicon wafer with 〈100〉 orientation by micro-electromechanical system (MEMS) technology and complementary metal oxide semiconductor (CMOS) technology, and they are packaged on a printed circuit board (PCB) using wire bonding technology. The experiment results show that the sensitivities of the pressure sensor (a=0) and the acceleration sensor (p=0) are 1.0 mV/kPa and 0.92 mV/g at room temperature and operating voltage of 5.0 V, respectively. It indicates that the proposed sensor can achieve the measurement of applied pressure and acceleration, and has good sensitivity characteristics. Meanwhile the mutual interference of them is weak.
A multifunction sensor based on nano-polysilicon thin film resistors which consists of pressure sensor and acceleration sensor is described. The two Wheatstone bridges consisting of piezoresistors are designed on the surface of square silicon membrane and the root of cantilever beam, respectively. The chips of pressure and acceleration sensors are fabricated on silicon wafer with 〈100〉 orientation by micro-electromechanical system (MEMS) technology and complementary metal oxide semiconductor (CMOS) technology, and they are packaged on a printed circuit board (PCB) using wire bonding technology. The experiment results show that the sensitivities of the pressure sensor (a=0) and the acceleration sensor (p=0) are 1.0 mV/kPa and 0.92 mV/g at room temperature and operating voltage of 5.0 V, respectively. It indicates that the proposed sensor can achieve the measurement of applied pressure and acceleration, and has good sensitivity characteristics. Meanwhile the mutual interference of them is weak.
2016,
28: 064116.
doi: 10.11884/HPLPB201628.064116
Abstract:
For effective use of graphene and conducting polymer, the composite films of laser scribed graphene (LSG) combined with poly(3,4-ethylenedioxythiophene) (PEDOT) are prepared with a facile laser scribing technology. Each component in the hybrid films provides unique and crucial function to achieve optimized electrochemical properties. In the presence of PEDOT nanoparticles, the LSG/PEDOT hybrid films are found to possess the better energy storage ability. The electrochemical performances of the films are evaluated with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charging-discharging (GCD) techniques. Volumetric capacity of composite film (64.33 F/cm3) is much higher than that of pure laser-scribed graphene film (3.89 F/cm3). The hybrid film exhibits excellent charge/discharge rate and good cycling stability, retaining 94.6% of its initial charge after 1000 cycles. The electrochemical performance improvement is primarily due to the effect of PEDOT nanoparticles in prevention of agglomeration of LSG layers and the increased surface areas accessible to electrolyte ions. It is anticipated that the PEDOT nanoparticles inserted into graphene oxide layers following laser scribing reduction procedure could be a promising large scale fabrication method for supercapacitor electrodes.
For effective use of graphene and conducting polymer, the composite films of laser scribed graphene (LSG) combined with poly(3,4-ethylenedioxythiophene) (PEDOT) are prepared with a facile laser scribing technology. Each component in the hybrid films provides unique and crucial function to achieve optimized electrochemical properties. In the presence of PEDOT nanoparticles, the LSG/PEDOT hybrid films are found to possess the better energy storage ability. The electrochemical performances of the films are evaluated with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charging-discharging (GCD) techniques. Volumetric capacity of composite film (64.33 F/cm3) is much higher than that of pure laser-scribed graphene film (3.89 F/cm3). The hybrid film exhibits excellent charge/discharge rate and good cycling stability, retaining 94.6% of its initial charge after 1000 cycles. The electrochemical performance improvement is primarily due to the effect of PEDOT nanoparticles in prevention of agglomeration of LSG layers and the increased surface areas accessible to electrolyte ions. It is anticipated that the PEDOT nanoparticles inserted into graphene oxide layers following laser scribing reduction procedure could be a promising large scale fabrication method for supercapacitor electrodes.
2016,
28: 064117.
doi: 10.11884/HPLPB201628.064117
Abstract:
The liquid droplet is usually adopted as the vehicle to pick micro-objects during micromanipulation tasks, and the conical manipulation probe is constantly employed as the capillary micromanipulation tool. We focus on investigations on water droplet on conical micromanipulation probe during air-cooled condensation. Mathematical models of microdroplet formation, including initial droplet formation, droplets coalescence and droplets motion, were established to analyze critical parameters. Parameter of the degree of subcooling that dominates the minimum radius and the growth rate of individual droplet was theoretically characterized. Accordingly, the process of droplet formation on a conical probe was simulated based on mathematical modeling. Subsequently, extensive experiments, with the assistance of a customized cooling module, were conducted to investigate the droplet formation on conical probes. The experimental results indicate that microdroplets formed on the conical probe during air-cooled condensation. A stable droplet was obtained via initial droplet formation, droplets coalescence and droplets motion. Droplet formation is various because of implementations of conical probe with varied apex angles and shapes, which directly influence the microdroplet formation.
The liquid droplet is usually adopted as the vehicle to pick micro-objects during micromanipulation tasks, and the conical manipulation probe is constantly employed as the capillary micromanipulation tool. We focus on investigations on water droplet on conical micromanipulation probe during air-cooled condensation. Mathematical models of microdroplet formation, including initial droplet formation, droplets coalescence and droplets motion, were established to analyze critical parameters. Parameter of the degree of subcooling that dominates the minimum radius and the growth rate of individual droplet was theoretically characterized. Accordingly, the process of droplet formation on a conical probe was simulated based on mathematical modeling. Subsequently, extensive experiments, with the assistance of a customized cooling module, were conducted to investigate the droplet formation on conical probes. The experimental results indicate that microdroplets formed on the conical probe during air-cooled condensation. A stable droplet was obtained via initial droplet formation, droplets coalescence and droplets motion. Droplet formation is various because of implementations of conical probe with varied apex angles and shapes, which directly influence the microdroplet formation.
2016,
28: 064118.
doi: 10.11884/HPLPB201628.064118
Abstract:
In ultraviolet induced nanoparticle colloid jet machining, the nanoparticle colloid microjet is used to effectively remove the material of the workpiece surface. A computational fluid dynamic model for vertical non-submerged jet is established to investigate the impacting hydrodynamics in ultraviolet induced nanoparticle colloid jet machining using a micro hole light-liquid coupling nozzle with an outlet diameter of 500m. With this model, the energy characteristics of fluid field and pressure distributions in the process of ultraviolet induced nanoparticle colloid jet machining are computed under the condition of vertical injection. Through numerical investigation, the dynamic response of two-dimensional TiO2 nanoparticle colloid jet impacting on a plane surface is studied. The simulation results indicate that the injection velocity of the TiO2 colloid in the micro-liquid coupling nozzle is about 30m/s when the jet pressure is 1 MPa, and the uniform bundling jet distance is about 5 mm. The static pressure of the nanoparticle colloid jet in the core area is concentrated, therefore the dynamic pressure and the velocity distribution of the synthetic velocity in the area of the impact of the colloid impinging jet is W shaped, and the maximum value is at the 2 mm diameter of the colloid jet.
In ultraviolet induced nanoparticle colloid jet machining, the nanoparticle colloid microjet is used to effectively remove the material of the workpiece surface. A computational fluid dynamic model for vertical non-submerged jet is established to investigate the impacting hydrodynamics in ultraviolet induced nanoparticle colloid jet machining using a micro hole light-liquid coupling nozzle with an outlet diameter of 500m. With this model, the energy characteristics of fluid field and pressure distributions in the process of ultraviolet induced nanoparticle colloid jet machining are computed under the condition of vertical injection. Through numerical investigation, the dynamic response of two-dimensional TiO2 nanoparticle colloid jet impacting on a plane surface is studied. The simulation results indicate that the injection velocity of the TiO2 colloid in the micro-liquid coupling nozzle is about 30m/s when the jet pressure is 1 MPa, and the uniform bundling jet distance is about 5 mm. The static pressure of the nanoparticle colloid jet in the core area is concentrated, therefore the dynamic pressure and the velocity distribution of the synthetic velocity in the area of the impact of the colloid impinging jet is W shaped, and the maximum value is at the 2 mm diameter of the colloid jet.
2016,
28: 064119.
doi: 10.11884/HPLPB201628.064119
Abstract:
A quartz tuning fork (QTF) micro-resonant temperature sensor which employs the shifting frequency corresponding to temperature is developed for high performance temperature measurement. The sensor is designed by the theoretical analysis, and the finite element simulation is employed to optimize the structure parameters. Micromachining technology is adopted in the fabrication of the QTF resonator using photolithography and etching technology. Performances of the QTF temperature sensor prototypes are experimentally investigated. Experimental results show that the resonance frequency of the QTF temperature sensor is approximately 36.545 kHz and the sensitivity is -1.9 Hz/℃ in the operating range of -20-100 ℃, with a non-linearity less than 0.18% and a hysteresis of 0.02%, which are in good agreement with analytical calculation results. Due to the excellent performances such as high accuracy, high sensitivity, low power and low cost, this QTF temperature sensor provides a commendable solution for high performance temperature measurement.
A quartz tuning fork (QTF) micro-resonant temperature sensor which employs the shifting frequency corresponding to temperature is developed for high performance temperature measurement. The sensor is designed by the theoretical analysis, and the finite element simulation is employed to optimize the structure parameters. Micromachining technology is adopted in the fabrication of the QTF resonator using photolithography and etching technology. Performances of the QTF temperature sensor prototypes are experimentally investigated. Experimental results show that the resonance frequency of the QTF temperature sensor is approximately 36.545 kHz and the sensitivity is -1.9 Hz/℃ in the operating range of -20-100 ℃, with a non-linearity less than 0.18% and a hysteresis of 0.02%, which are in good agreement with analytical calculation results. Due to the excellent performances such as high accuracy, high sensitivity, low power and low cost, this QTF temperature sensor provides a commendable solution for high performance temperature measurement.
2016,
28: 064120.
doi: 10.11884/HPLPB201628.064120
Abstract:
In this paper, the polystyrene/nano-silica composite particles were prepared and characterized according to the following steps. First, the nano-silica particles were pretreated with the surfactants under ultrasonic field. Secondly, the dispersion polymerization of styrene in a water-ethanol medium, with poly(N-vinyl pyrrolidone) (PVP) as stabilizer and 2, 2-azobisizobutyronitrile (AIBN) as initiator in the presence of nano-silica particles was initiated through ultrasonic irradiation by taking its advantages of multieffect, i.e., dispersion, crushing, activation, and initiation. Finally, the encapsulation of composite particles were investigated with SEM, TEM, FTIR and X-ray photoelectron spectroscopy (XPS).
In this paper, the polystyrene/nano-silica composite particles were prepared and characterized according to the following steps. First, the nano-silica particles were pretreated with the surfactants under ultrasonic field. Secondly, the dispersion polymerization of styrene in a water-ethanol medium, with poly(N-vinyl pyrrolidone) (PVP) as stabilizer and 2, 2-azobisizobutyronitrile (AIBN) as initiator in the presence of nano-silica particles was initiated through ultrasonic irradiation by taking its advantages of multieffect, i.e., dispersion, crushing, activation, and initiation. Finally, the encapsulation of composite particles were investigated with SEM, TEM, FTIR and X-ray photoelectron spectroscopy (XPS).
2016,
28: 064121.
doi: 10.11884/HPLPB201628.064121
Abstract:
The ring shaped resonator is a typical structure which is widely applied in MEMS resonator study. Elliptic mode is the basic in-plane vibration mode of ring resonator. This paper presents the numerical analysis of anchor effect in the elliptic mode ring resonator based on energy method. The results show that activating the anchor mode can help to reduce the anchor loss. However, the quality factor of resonator can not be thus increased as the researchers previously suggested. The energy method suggested in this study provides an instructive way of anchor geometry design for MEMS resonators.
The ring shaped resonator is a typical structure which is widely applied in MEMS resonator study. Elliptic mode is the basic in-plane vibration mode of ring resonator. This paper presents the numerical analysis of anchor effect in the elliptic mode ring resonator based on energy method. The results show that activating the anchor mode can help to reduce the anchor loss. However, the quality factor of resonator can not be thus increased as the researchers previously suggested. The energy method suggested in this study provides an instructive way of anchor geometry design for MEMS resonators.
2016,
28: 064122.
doi: 10.11884/HPLPB201628.064122
Abstract:
In order to separate the permanent gases from low carbon hydrocarbons, a gas chromatography (GC) column packed with porapak Q as stationary phase was fabricated based on MEMS technology. In this work, the channels on the glass wafer and the silicon wafer were fabricated by a laser etching technology (LET). LET is an effective method to etch a deep channels on the glass wafer as well as on the silicon wafer, so the depth of the channels can be substantially increased by bonding the channels on the silicon together with the channels on the glass wafer. The fabricated column with a rectangular cross section of 1.2 mm (depth) 0.6 mm (width) has a large aspect ratio of 2∶1, which improves the resolution of the column. The experiment shows that the fabricated column demonstrated large sample capacity and completely separated the permanent gases CO and SO2 from low hydrocarbons.
In order to separate the permanent gases from low carbon hydrocarbons, a gas chromatography (GC) column packed with porapak Q as stationary phase was fabricated based on MEMS technology. In this work, the channels on the glass wafer and the silicon wafer were fabricated by a laser etching technology (LET). LET is an effective method to etch a deep channels on the glass wafer as well as on the silicon wafer, so the depth of the channels can be substantially increased by bonding the channels on the silicon together with the channels on the glass wafer. The fabricated column with a rectangular cross section of 1.2 mm (depth) 0.6 mm (width) has a large aspect ratio of 2∶1, which improves the resolution of the column. The experiment shows that the fabricated column demonstrated large sample capacity and completely separated the permanent gases CO and SO2 from low hydrocarbons.
2016,
28: 064123.
doi: 10.11884/HPLPB201628.064123
Abstract:
Dimension uncertainty inevitably occurs in almost every fabrication of micro structure due to its small size and uniformity of material. The dimension error, however, will result in the asymmetry of the sensitive structure. The unsymmetrical structure will change the distribution of the thermal stress when the micro sensors are subjected to changed temperature and further impact the thermal stability of devices which is characterized by the quantity of thermal drift. This study investigates the effects of fabrication error on the thermal drift of a comb capacitive micro accelerometer fabricated by deep reactive ion etching(DRIE) process. The accelerometers with supporting folded beams width error ranging from the ideal layout design to the actual fabricated dimension are modeled to simulate the deformation of sensitive component induced by temperature change. The thermal drifts are acquired by the calculation of the differential capacitance of the deformed structure. In order to reduce the thermal drift induced by the fabrication error, the design dimension of the beam width is enlarged under the premise of constant sensitivity of the accelerometer. The calculated results indicate that the supporting beam fabrication error will significantly affect the thermal drift of the capacitive micro accelerometers and an increased design dimension of the beam width can improve the symmetry of the sensor, and then reduce the thermal drift.
Dimension uncertainty inevitably occurs in almost every fabrication of micro structure due to its small size and uniformity of material. The dimension error, however, will result in the asymmetry of the sensitive structure. The unsymmetrical structure will change the distribution of the thermal stress when the micro sensors are subjected to changed temperature and further impact the thermal stability of devices which is characterized by the quantity of thermal drift. This study investigates the effects of fabrication error on the thermal drift of a comb capacitive micro accelerometer fabricated by deep reactive ion etching(DRIE) process. The accelerometers with supporting folded beams width error ranging from the ideal layout design to the actual fabricated dimension are modeled to simulate the deformation of sensitive component induced by temperature change. The thermal drifts are acquired by the calculation of the differential capacitance of the deformed structure. In order to reduce the thermal drift induced by the fabrication error, the design dimension of the beam width is enlarged under the premise of constant sensitivity of the accelerometer. The calculated results indicate that the supporting beam fabrication error will significantly affect the thermal drift of the capacitive micro accelerometers and an increased design dimension of the beam width can improve the symmetry of the sensor, and then reduce the thermal drift.
2016,
28: 064124.
doi: 10.11884/HPLPB201628.064124
Abstract:
SU-8 negative photoresist has wide applications due to its excellent properties, such as good mechanical property, bio-compatibility and thermal stability. Nickel is often employed in MEMS devices due to its good mechanical property and chemical resistance. In MEMS actuator, elastic elements are generally fabricated by electrodeposited nickel. SU-8 will form a highly cross-linked network polymer after exposing to UV irradiation, which is difficult to dissolve in strong acid, alkali, and convenient organic solvent. Especially, highly cross-lined SU-8 is very hard to be removed after metal electroplating. Many SU-8 removal methods have been developed, including physical and oxidative techniques. Oxidative methods can reliably and effectively remove the SU-8. But they tend to damage or change the properties of the electrodeposited metal. In this paper, mechanical properties of electrodeposited nickel were investigated before and after SU-8 removal by using plasma downstream chemical etching (DCE) and molten salt bath oxidizing method. The results show that the Youngs modulus of the electrodeposited nickel decreased 18% and 36% after DCE etching and molten salt bath oxidizing, respectively. The hardness test results showed little change by using these two SU-8 removal methods.
SU-8 negative photoresist has wide applications due to its excellent properties, such as good mechanical property, bio-compatibility and thermal stability. Nickel is often employed in MEMS devices due to its good mechanical property and chemical resistance. In MEMS actuator, elastic elements are generally fabricated by electrodeposited nickel. SU-8 will form a highly cross-linked network polymer after exposing to UV irradiation, which is difficult to dissolve in strong acid, alkali, and convenient organic solvent. Especially, highly cross-lined SU-8 is very hard to be removed after metal electroplating. Many SU-8 removal methods have been developed, including physical and oxidative techniques. Oxidative methods can reliably and effectively remove the SU-8. But they tend to damage or change the properties of the electrodeposited metal. In this paper, mechanical properties of electrodeposited nickel were investigated before and after SU-8 removal by using plasma downstream chemical etching (DCE) and molten salt bath oxidizing method. The results show that the Youngs modulus of the electrodeposited nickel decreased 18% and 36% after DCE etching and molten salt bath oxidizing, respectively. The hardness test results showed little change by using these two SU-8 removal methods.
2016,
28: 064125.
doi: 10.11884/HPLPB201628.064125
Abstract:
The size reference material is used to test and calibrate apparatus, evaluate measure method, and ensure sample values. It is important in industry measurement, controling of products quality and science studying. In the present paper, crosslinked polystyrene microspheres with an average size of about 3.0 m were prepared by dispersion polymerization. Compared with the micro PS particle prepared from linear PS, the PS micro particle prepared from cross-linked PS shows superior resistance to solvent and heat, with the glass transition temperature increasement of 28.6 ℃ and remains insoluble in normal solvents. F-test and t-test were used to test the uniformity and stability of the sample. The quantification was carried out by independent measurement techniques named scanning electron microscope (SEM), which was calibrated with NIST Standard Reference Material (SRM2800). It is shown that the sizes of these PS spheres samples are 2.84 m and the expanded uncertainty is 0.08 m. The quantification process, the uniformity and the stability of these samples meet the demands of secondary standard reference materials of China.
The size reference material is used to test and calibrate apparatus, evaluate measure method, and ensure sample values. It is important in industry measurement, controling of products quality and science studying. In the present paper, crosslinked polystyrene microspheres with an average size of about 3.0 m were prepared by dispersion polymerization. Compared with the micro PS particle prepared from linear PS, the PS micro particle prepared from cross-linked PS shows superior resistance to solvent and heat, with the glass transition temperature increasement of 28.6 ℃ and remains insoluble in normal solvents. F-test and t-test were used to test the uniformity and stability of the sample. The quantification was carried out by independent measurement techniques named scanning electron microscope (SEM), which was calibrated with NIST Standard Reference Material (SRM2800). It is shown that the sizes of these PS spheres samples are 2.84 m and the expanded uncertainty is 0.08 m. The quantification process, the uniformity and the stability of these samples meet the demands of secondary standard reference materials of China.
2016,
28: 064126.
doi: 10.11884/HPLPB201628.064126
Abstract:
With the obvious increase of integrating capacity and density in System-in-Package (SIP), it is more and more difficult for traditional cooling methods (e.g., thermal vias through substrate, air cooling) to meet the cooling requirements of high power application. Liquid cooling microchannels integrated into LTCC packaging substrate have been demonstrated as a competitive packaging substrate for SIP of high power applications. In this paper, heat transfer performance of microchannels embedded in LTCC packaging substrate for electronic cooling application is investigated. Proprietary process is selected to make LTCC microchannel samples. Three kinds of microchannels are designed and samples are fabricated, including serpentine, spiral and parallel microchannels. The effects of channel pattern, Reynolds numbers, flow rate and thermal conductivity of substrate on heat transfer performance of LTCC substrate are experimentally measured and simulated with commercial software COMSOL multi-physics. The heat transfer performance in term of maximum working temperature drop is measured with infrared thermometer. With the deionized water flow rate of 10 mL/min and equivalent power source of 2 W/cm2, parallel microchannel cuts the substrate temperature by 75.4 ℃ under inlet pressure drop of 3.1 kPa, serpentine microchannel by 80.2 ℃ under inlet pressure drop of 85.8 kPa, spiral microchannel by 86.7 ℃ under inlet pressure drop of 103.1 kPa. Among the three microchannel patterns, parallel microchannel has the smallest Reynolds numbers and the best cooling performance under the same inlet pressure drop. Narrow parallel microchannel (channel width 0.4 mm) with the same channel density and flow rate can cut substrate working temperature 10 ℃ more than the relatively wide microchannel (channel width 0.8 mm). Simulation results indicate that thermal conductivity of LTCC packaging substrate can enhance heat transfer performance by 13%. Results show microchannels embedded in LTCC substrate are suitable for thermal management of high power system.
With the obvious increase of integrating capacity and density in System-in-Package (SIP), it is more and more difficult for traditional cooling methods (e.g., thermal vias through substrate, air cooling) to meet the cooling requirements of high power application. Liquid cooling microchannels integrated into LTCC packaging substrate have been demonstrated as a competitive packaging substrate for SIP of high power applications. In this paper, heat transfer performance of microchannels embedded in LTCC packaging substrate for electronic cooling application is investigated. Proprietary process is selected to make LTCC microchannel samples. Three kinds of microchannels are designed and samples are fabricated, including serpentine, spiral and parallel microchannels. The effects of channel pattern, Reynolds numbers, flow rate and thermal conductivity of substrate on heat transfer performance of LTCC substrate are experimentally measured and simulated with commercial software COMSOL multi-physics. The heat transfer performance in term of maximum working temperature drop is measured with infrared thermometer. With the deionized water flow rate of 10 mL/min and equivalent power source of 2 W/cm2, parallel microchannel cuts the substrate temperature by 75.4 ℃ under inlet pressure drop of 3.1 kPa, serpentine microchannel by 80.2 ℃ under inlet pressure drop of 85.8 kPa, spiral microchannel by 86.7 ℃ under inlet pressure drop of 103.1 kPa. Among the three microchannel patterns, parallel microchannel has the smallest Reynolds numbers and the best cooling performance under the same inlet pressure drop. Narrow parallel microchannel (channel width 0.4 mm) with the same channel density and flow rate can cut substrate working temperature 10 ℃ more than the relatively wide microchannel (channel width 0.8 mm). Simulation results indicate that thermal conductivity of LTCC packaging substrate can enhance heat transfer performance by 13%. Results show microchannels embedded in LTCC substrate are suitable for thermal management of high power system.
2016,
28: 064127.
doi: 10.11884/HPLPB201628.064127
Abstract:
In the last few years, with the rapid development of micro-opto-electro-mechanical-systems(MOEMS), near-infrared(NIR) spectrometers are moving towards low cost, high performance and miniaturization. As a key component of NIR micro-spectrometers, the scanning grating mirror has an imponderable advantage on diffraction efficiency compared to other grating mirrors, which makes it feasible to develop high optical detecting sensitivity systems with one single photodiode. In order to improve the detecting performance of NIR spectrometers, a single silicon MOEMS scanning grating mirror has been designed, which integrates a high diffraction efficiency blazed grating on the top and an electromagnetic actuator on the bottom. Based on a tilted (111) silicon substrate, the scanning grating mirror structure can be easily fabricated by micromachining technology. Meanwhile, a simulation has also been carried out by optical software and finite element analysis(FEA), and the results show that the dynamic diffraction efficiency is more than 54% and the peak value reaches 90% in the spectrum range of 800-1800 nm, meanwhile the maximum torsion angle of MOMES scanning grating mirror is 4.55 at the frequency of 484.38 Hz.
In the last few years, with the rapid development of micro-opto-electro-mechanical-systems(MOEMS), near-infrared(NIR) spectrometers are moving towards low cost, high performance and miniaturization. As a key component of NIR micro-spectrometers, the scanning grating mirror has an imponderable advantage on diffraction efficiency compared to other grating mirrors, which makes it feasible to develop high optical detecting sensitivity systems with one single photodiode. In order to improve the detecting performance of NIR spectrometers, a single silicon MOEMS scanning grating mirror has been designed, which integrates a high diffraction efficiency blazed grating on the top and an electromagnetic actuator on the bottom. Based on a tilted (111) silicon substrate, the scanning grating mirror structure can be easily fabricated by micromachining technology. Meanwhile, a simulation has also been carried out by optical software and finite element analysis(FEA), and the results show that the dynamic diffraction efficiency is more than 54% and the peak value reaches 90% in the spectrum range of 800-1800 nm, meanwhile the maximum torsion angle of MOMES scanning grating mirror is 4.55 at the frequency of 484.38 Hz.
2016,
28: 064128.
doi: 10.11884/HPLPB201628.064128
Abstract:
Terahertz (THz) communications are expected to be the next frontier for wireless nanonetworks. Nanonetworks are formed by nanodevices (tiny devices at the nanoscale or molecular scale). The high transmittable data rate for nanonetwork is investigated based on a new model of the THz wave atmospheric propagation of attenuation. The THz wave atmospheric attenuation experimental results obtained from the THz-time domain spectroscopy (THz-TDS) technique are analyzed using this model. The intensity and location of the observed absorption lines are in good agreement with the calculated spectrum. The total path loss and the maximum transmittable data rate are numerically simulated when a THz wave propagates over an extremely short distance. Furthermore, the channel capacity in the THz band (0.1-5 THz) is investigated by this mode. It is shown that the molecular absorption loss is significant in THz band; data with high rates of more than 100 Gbit/s, which take advantage of the unique characteristics in the physical channels while minimizing the impairments of molecular absorption, can be transmitted via the THz channels for a greatly short transmission distance.
Terahertz (THz) communications are expected to be the next frontier for wireless nanonetworks. Nanonetworks are formed by nanodevices (tiny devices at the nanoscale or molecular scale). The high transmittable data rate for nanonetwork is investigated based on a new model of the THz wave atmospheric propagation of attenuation. The THz wave atmospheric attenuation experimental results obtained from the THz-time domain spectroscopy (THz-TDS) technique are analyzed using this model. The intensity and location of the observed absorption lines are in good agreement with the calculated spectrum. The total path loss and the maximum transmittable data rate are numerically simulated when a THz wave propagates over an extremely short distance. Furthermore, the channel capacity in the THz band (0.1-5 THz) is investigated by this mode. It is shown that the molecular absorption loss is significant in THz band; data with high rates of more than 100 Gbit/s, which take advantage of the unique characteristics in the physical channels while minimizing the impairments of molecular absorption, can be transmitted via the THz channels for a greatly short transmission distance.
2016,
28: 064129.
doi: 10.11884/HPLPB201628.064129
Abstract:
Combined with the quality giant magnetostrictive material (GMM), a GMM transducer with bow type structure is proposed based on the triangle amplification principle. The purpose is to improve the actuation stroke of the transducer for bigger sound intensity. At the same time, the requirements of small size of the device and less assembly parts are satisfied. This structure takes the GMM rod as the driving element. With one end of bow type structure being fixed, the bidirectional output is transformed into a one-way output. And the output displacement is further increased using the flexible hinge structure. The working principle of the transducer is analyzed. The theoretical magnification of the structure is 2.73 by analytical calculation. The result is close to that of 2.8 with the finite element simulation model. A prototype is made to be tested through the corresponding test system. And the maximum output displacement is 15.5 m in 1 kHz range, which is close to the simulation result of 14.058 m. The bow type structure achieves the enlarge of the transducers output displacement. And the corresponding analysis method has reflected the output characteristics of the transducer better.
Combined with the quality giant magnetostrictive material (GMM), a GMM transducer with bow type structure is proposed based on the triangle amplification principle. The purpose is to improve the actuation stroke of the transducer for bigger sound intensity. At the same time, the requirements of small size of the device and less assembly parts are satisfied. This structure takes the GMM rod as the driving element. With one end of bow type structure being fixed, the bidirectional output is transformed into a one-way output. And the output displacement is further increased using the flexible hinge structure. The working principle of the transducer is analyzed. The theoretical magnification of the structure is 2.73 by analytical calculation. The result is close to that of 2.8 with the finite element simulation model. A prototype is made to be tested through the corresponding test system. And the maximum output displacement is 15.5 m in 1 kHz range, which is close to the simulation result of 14.058 m. The bow type structure achieves the enlarge of the transducers output displacement. And the corresponding analysis method has reflected the output characteristics of the transducer better.
2016,
28: 064130.
doi: 10.11884/HPLPB201628.064130
Abstract:
Resonant pressure micro sensors with differential design can achieve high linearity and sensitivity, and reduce the temperature drift. However, the reported differential resonant pressure micro sensors suffer from sensitivity mismatch among two resonant beams, leading to compromised performance. This problem is resulted from the undesirable choice of relative position of two resonant beams based on numerical simulations, which does not agree with experimental results. To address this issue, this paper presents a differential resonant pressure micro sensor with the sensitivity of two resonant beams fine-tuned. Based on numerical simulations, the sensitivity of the two resonant beams is designed as 46 Hz/kPa while the experimental results are 45 Hz/kPa for the central beam and -44 Hz/kPa for the side beam.
Resonant pressure micro sensors with differential design can achieve high linearity and sensitivity, and reduce the temperature drift. However, the reported differential resonant pressure micro sensors suffer from sensitivity mismatch among two resonant beams, leading to compromised performance. This problem is resulted from the undesirable choice of relative position of two resonant beams based on numerical simulations, which does not agree with experimental results. To address this issue, this paper presents a differential resonant pressure micro sensor with the sensitivity of two resonant beams fine-tuned. Based on numerical simulations, the sensitivity of the two resonant beams is designed as 46 Hz/kPa while the experimental results are 45 Hz/kPa for the central beam and -44 Hz/kPa for the side beam.
2016,
28: 064131.
doi: 10.11884/HPLPB201628.064131
Abstract:
stopper can be used for shock protection, however, traditional stopper may generate secondary shock which could result in fracture, debris, and performance shifts of the device. The problem can be efficiently solved by introducing elastic stopper, but its protective effect is greatly influenced by stoppers parameters. In order to get the best parameter, impact dynamic model of MEMS is established at first, based on which the factors affecting shock response are extracted. Then the parameters of elastic stopper, including elastic coefficient and limit distance are emphatically analyzed, the method of designing elastic stopper and final result are finally provided. Results show that: effective shock protection must minimize the motion of microstructure as well as maximize buffer performance. Besides, minimizing limit distance is also helpful to improve anti-shock ability.
stopper can be used for shock protection, however, traditional stopper may generate secondary shock which could result in fracture, debris, and performance shifts of the device. The problem can be efficiently solved by introducing elastic stopper, but its protective effect is greatly influenced by stoppers parameters. In order to get the best parameter, impact dynamic model of MEMS is established at first, based on which the factors affecting shock response are extracted. Then the parameters of elastic stopper, including elastic coefficient and limit distance are emphatically analyzed, the method of designing elastic stopper and final result are finally provided. Results show that: effective shock protection must minimize the motion of microstructure as well as maximize buffer performance. Besides, minimizing limit distance is also helpful to improve anti-shock ability.
2016,
28: 064132.
doi: 10.11884/HPLPB201628.064132
Abstract:
Total phosphorous (TP) is one of the important indicators of water pollution and eutrophication, and the detection of total phosphorus is of important significance. Many digestion methods have been used for the detection of TP. TiO2/UV photocatalytic method, as an effective way to degrade organic substances, has been applied to TP digestion due to the advantages of low power consumption, reagent-free. However, due to the recombination of electron-hole pairs in the digestion process, a higher efficiency of conversion is desired. This paper introduces a photoelectrocatalytic digestion method for TP detection by applying an appropriate potential between the TiO2 working electrode and counter electrode to prevent the recombination of electron-hole pairs. The characterization of TiO2 nanotubes (NTs), which were prepared by anodic oxidation and used as the photocatalyst for TP digestion based on photoelectrocatalysis, was carried out by FESEM and XRD. The digestion rate of TP was evaluated by the concentration of phosphate which was measured by analyzer. The corresponding digestion rate for 1 mg/L (phosphorus meter) sodium polyphosphate solution is 4.1%, 44.7% and 65.4% in the electrocatalytic process, photocatalytic process and photoelectrocatalytic process, respectively. The results show that the photoelectrocatalytic digestion process is more efficient than the other two processes, and it has the potential to be applied to the pretreatment of TP detection.
Total phosphorous (TP) is one of the important indicators of water pollution and eutrophication, and the detection of total phosphorus is of important significance. Many digestion methods have been used for the detection of TP. TiO2/UV photocatalytic method, as an effective way to degrade organic substances, has been applied to TP digestion due to the advantages of low power consumption, reagent-free. However, due to the recombination of electron-hole pairs in the digestion process, a higher efficiency of conversion is desired. This paper introduces a photoelectrocatalytic digestion method for TP detection by applying an appropriate potential between the TiO2 working electrode and counter electrode to prevent the recombination of electron-hole pairs. The characterization of TiO2 nanotubes (NTs), which were prepared by anodic oxidation and used as the photocatalyst for TP digestion based on photoelectrocatalysis, was carried out by FESEM and XRD. The digestion rate of TP was evaluated by the concentration of phosphate which was measured by analyzer. The corresponding digestion rate for 1 mg/L (phosphorus meter) sodium polyphosphate solution is 4.1%, 44.7% and 65.4% in the electrocatalytic process, photocatalytic process and photoelectrocatalytic process, respectively. The results show that the photoelectrocatalytic digestion process is more efficient than the other two processes, and it has the potential to be applied to the pretreatment of TP detection.
2016,
28: 064133.
doi: 10.11884/HPLPB201628.064133
Abstract:
The thin film bulk acoustic resonator (FBAR) performance model contains two relationships: one is the relationship between the effective electromechanical coupling coefficient and the shape factor (ratio of area and perimeter) of FBAR, the other is the relationship between the quality factor and the shape factor. The parameter in the former is the equivalent width of region at the edge of FBAR. The parameter in the latter is the transmission coefficient of lateral acoustic energy in FBAR. In order to make the FBAR performance model be applied for different film structure, materials and process technology of FBAR, a new procedure for extracting the parameters of FBAR performance model was proposed. In the case of 5 layers composite structure FBAR, several FBARs with the same film structure and different shape factor were fabricated on the same wafer. According to one of the FBARs, the effective electromechanical coupling coefficient and the quality factor were simulated by Mason circuit model and measured by vector network analyzer and RF probe station. The two parameters in FBAR performance model were solved by taking these values into the two relationships. After determining the parameters, the FBAR performance model was used to predict the effective electromechanical coupling coefficient and the quality factor of other FBARs on wafer. Compared to measured value, the relative error of prediction values is within 3%, which verifies the validity of the procedure for extracting parameters.
The thin film bulk acoustic resonator (FBAR) performance model contains two relationships: one is the relationship between the effective electromechanical coupling coefficient and the shape factor (ratio of area and perimeter) of FBAR, the other is the relationship between the quality factor and the shape factor. The parameter in the former is the equivalent width of region at the edge of FBAR. The parameter in the latter is the transmission coefficient of lateral acoustic energy in FBAR. In order to make the FBAR performance model be applied for different film structure, materials and process technology of FBAR, a new procedure for extracting the parameters of FBAR performance model was proposed. In the case of 5 layers composite structure FBAR, several FBARs with the same film structure and different shape factor were fabricated on the same wafer. According to one of the FBARs, the effective electromechanical coupling coefficient and the quality factor were simulated by Mason circuit model and measured by vector network analyzer and RF probe station. The two parameters in FBAR performance model were solved by taking these values into the two relationships. After determining the parameters, the FBAR performance model was used to predict the effective electromechanical coupling coefficient and the quality factor of other FBARs on wafer. Compared to measured value, the relative error of prediction values is within 3%, which verifies the validity of the procedure for extracting parameters.
2016,
28: 064134.
doi: 10.11884/HPLPB201628.064134
Abstract:
The effect of ultraviolet irradiation on the dielectric properties of polyetherimide (PEI) film samples was investigated. FT-IR and SEM were used to characterize the molecular structure and the surface morphology of the untreated and treated PEI films in different UV irradiation time. The results show that the absorption peak of the irradiated PEI film at 1724 cm-1 was greater than that of the virgin, which indicates the amount of C=O groups increases with increasing irradiation time, and cracks occurred on the PEI surface. The dielectric properties of PEI films were also studied in detail. The results show that, with the increase of irradiation time, the relative dielectric constant and the dielectric dissipation factor increased, surface resistivity decreased, and volume resistivity was almost unchanged. PEI film of DC breakdown strength firstly increased, and then decreased with the increase of radiation time. Moreover, the irradiated films breakdown strengh at a certain irradiation dose is 20% greater than that of the original film, which may be attributed to the crosslinking action under the ultraviolet irradiation.
The effect of ultraviolet irradiation on the dielectric properties of polyetherimide (PEI) film samples was investigated. FT-IR and SEM were used to characterize the molecular structure and the surface morphology of the untreated and treated PEI films in different UV irradiation time. The results show that the absorption peak of the irradiated PEI film at 1724 cm-1 was greater than that of the virgin, which indicates the amount of C=O groups increases with increasing irradiation time, and cracks occurred on the PEI surface. The dielectric properties of PEI films were also studied in detail. The results show that, with the increase of irradiation time, the relative dielectric constant and the dielectric dissipation factor increased, surface resistivity decreased, and volume resistivity was almost unchanged. PEI film of DC breakdown strength firstly increased, and then decreased with the increase of radiation time. Moreover, the irradiated films breakdown strengh at a certain irradiation dose is 20% greater than that of the original film, which may be attributed to the crosslinking action under the ultraviolet irradiation.
2016,
28: 064112.
doi: 10.11884/HPLPB201628.064112
Abstract:
This paper presents an energy harvester which operates at less than 1 kHz and consists of a micro siliconlead zirconate titanate (Si-PZT) cantilever and a nickel mass block on the cantilever. The energy harvester is a device that can convert the ambient mechanical vibration into electrical energy employing the piezoelectric effect. The micro piezo cantilever structure was fabricated by eutectic bonding using gold thin film as a bonding layer. A PZT mechanical polishing process was used to thin the bulk PZT. The thinnest PZT film obtained was 8 m. A nickel mass block (2 mm2 mm0.6 mm) was fabricated using micro electroforming process. By optimizing the bonding and polishing processes, the thickness of fabricated Si-PZT cantilever was about 71 m, and the thicknesses of the silicon beam and the PZT beam were about 47 m and 24 m, respectively. The results showed that the AC output voltage of the micro energy harvester was around 958 mV at the resonant frequency of 950 Hz and the acceleration of 1.0g.
This paper presents an energy harvester which operates at less than 1 kHz and consists of a micro siliconlead zirconate titanate (Si-PZT) cantilever and a nickel mass block on the cantilever. The energy harvester is a device that can convert the ambient mechanical vibration into electrical energy employing the piezoelectric effect. The micro piezo cantilever structure was fabricated by eutectic bonding using gold thin film as a bonding layer. A PZT mechanical polishing process was used to thin the bulk PZT. The thinnest PZT film obtained was 8 m. A nickel mass block (2 mm2 mm0.6 mm) was fabricated using micro electroforming process. By optimizing the bonding and polishing processes, the thickness of fabricated Si-PZT cantilever was about 71 m, and the thicknesses of the silicon beam and the PZT beam were about 47 m and 24 m, respectively. The results showed that the AC output voltage of the micro energy harvester was around 958 mV at the resonant frequency of 950 Hz and the acceleration of 1.0g.
