A high sensitive MEMS capacitive fingerprint sensor using slotted membrane

In this paper a novel single-chip microelectromechanical systems (MEMS) capacitive fingerprint sensor with slotted membrane is developed to improve the sensitivity. The capacitive sensor consists of a thin, flexible membrane and a rigid back plate with air gap. In this study with making slots in upper electrode to decrease the mechanical stiffness of the membrane, using proportional T-shaped protrusion on diaphragm in order to concentrate the force from finger ridges, making holes in lower electrode to reduce the air damping and using low stress material for diaphragm, we have been succeeded to design a novel MEMS fingerprint sensor with high sensitivity compared with the previous works (Sato et al., IEEE Trans Electron Devices 52:1026–1032, 2005; Damghanian and Majlis, 2008 IEEE International Conference on Semiconductor Electronics (ICSE 2008), pp 634–638 2008). The behaviors of the fingerprint sensor with clamped and slotted membranes are analyzed using the finite element method (FEM). The results yield a sensitivity of 1.44 fF/Mpa for the clamped and 3.22 fF/Mpa for the slotted fingerprint sensor with a 50 × 50 μm² diaphragm. The sensitivity of the slotted structure is increased 2.236 times.     

A high-performance MEMS capacitive strain sensing system

This paper describes the design of a functional strain sensing module with large dynamic range (80 dB), DC to 10 kHz response, high resolution, and mini size for industrial applications, such as the rolling-element bearings research. The design of the MEMS capacitive strain sensor employs mechanical amplifications of package design and buckle beams as well as the linear differential comb capacitor. The sensor is interfaced with a low noise charge amplifier, mixer, and filter circuits to provide an analog output that demonstrated a resolution of 0.09 microstrains with a maximum range of ±1000 microstrains. The sensor and the electronic circuits, including a temperature sensor, can be integrated on a chip, and packaged as a small functional unit. Additional electronics were integrated with the interface circuit on the chip that provide A/D conversion, radio frequency power supply, and digital signal telemetry to a near-by control unit. Preliminary test results are compared with the design simulation.     

A novel high sensitive MEMS intraocular capacitive pressure sensor

This paper presents a novel high sensitive MEMS capacitive pressure sensor that can be used as a part of LC tank implant circuit for biomedical applications. The pressure sensor has been designed to measure pressures in the range of 0–60 mmHg that is in the range of intraocular pressure sensors. Intraocular pressure sensors are important in detection and treatment of an incurable disease called glaucoma. In this paper two methods are presented to improve the sensitivity of the capacitive pressure sensor. First low stress doped polysilicon material is used as a biocompatible material instead of p++silicon in previous work (Gu in Microfabrication of an intraocular pressure sensor, M.Sc Thesis, Michigan State University, Department of Electrical and Computer Engineering, 2005) and then some slots are added to the poly Si diaphragm. The novelty of this research relies on adding some slots on the sensor diaphragm to reduce the effect of residual stress and stiffness of diaphragm. The slotted diaphragm makes capacitive pressure sensor more sensitive that is more suitable for measuring intraocular pressure. The results yield a sensor sensitivity of 1.811 × 10^?5 for p++silicon clamped, 2.464 × 10^?5 1/Pa for polysilicon clamped and 1.13 × 10^?4 1/Pa for polysilicon slotted diaphragm. It can be seen that the sensitivity of the sensor with slotted poly Si diaphragm increased 6.2 times compared with previous work (clamped p++silicon diaphragm).     

Multi-level and multi-objective design optimisation of a MEMS bandpass filter

Microelectromechanical system (MEMS) design is often complex, containing multiple disciplines but also conflicting objectives. Designers are often faced with the problem of balancing what objectives to focus upon and how to incorporate modeling and simulation tools across multiple levels of abstraction in the design optimization process. In particular due to the computational expense of some of these simulation methods there are restrictions on how much optimization can occur. In this paper we aim to demonstrate the application of multi-objective and multi-level design optimisation strategies to a MEMS bandpass filter. This provides for designers the ability to evolve solutions that can match multiple objectives. In order to address the problem of a computationally expensive design process a novel multi-level evaluation strategy is developed. In addition a new approach for bandpass filter modeling and optimization is presented based up the electrical equivalent circuit method. In order to demonstrate this approach a comparison is made to previous attempts to design similar bandpass filters. Results are comparable in design but at a significant reduction in functional evaluations, needing only 10,000 functional evaluations in comparison to 2.6 million with the previous work.     

Optimizing a microstrip bandpass filter using electromagnetics

In this article, we will describe the design and optimization of a microstrip bandpass filter using an electromagnetic field-solver as the analysis engine. The filter is analyzed and optimized using a cascade of field-solver solutions. Convergence issues and proper mesh setup for the various subnetworks are discussed. And the necessary compromise between accuracy and solution time is also explored. © 1995 John Wiley & Sons, Inc.     

A novel MEMS capacitive microphone using spring-type diaphragm

Microsystem Technologies - In this paper, we present a new design of diaphragm that supported by frog arms for MEMS capacitive microphone structure. The proposed diaphragm reduces the air damping...     

应用于混合频率综合器的耦合微带线带通滤波器

设计了一种应用在PLL+DDS环外混频混合频率综合器系统末端的平行耦合微带线带通滤波器,用于抑制频率综合器输出频谱中的杂散和谐波分量。带通滤波器采用平行耦合微带线形式,实现了中心频率2 350 MHz,带宽50 MHz,带内最大损耗为-5 dB,带外在2 225 MHz损耗为-47.7 dB、在2 285 MHz损耗为-29.0 dB的指标。通过对此滤波器及此混合频率综合器输出信号的测试,验证了滤波器可以有效抑制此结构的频率综合器输出频谱中的杂散和谐波分量。     

A new scheme for reducing breathing trouble through MEMS based capacitive pressure sensor

In this paper, a treatment of respiratory disorders with brushless DC motor (BLDC) driven positive airway pressure (PAP) respirator is developed. The proposed schema of the system consists of a BLDC motor driven blower fan aided by a MEMS capacitive type pressure sensor to measure respiration rate (RR). To measure the respiration rate, the array of such sensors are mounted below right nostril (RN) and left nostril (LN), in such a way that the nasal airflow during inspiration and expiration impinge on the sensor diaphragms directly. Due to irregularities in nasal airflow in some respiratory diseases, the RR varies from the normal rate (12–20). Thus, a supporting airflow regulatory system has been designed to reduce abnormalities in RR. The supporting system consists of a positive airway pressure (PAP) respirator with a blower fan to relieve patients breathing abnormalities. The MEMS based RR sensors help to monitor patients breathing rate continuously and finally maintain the required air pressure/flow by regulating the rpm of the blower fan through BLDC motor drive. In order to implement such a control action, we have chosen the sensorless drive of BLDC motor to construct a transportable as well as noise immune system. An algorithm has been developed to sustain normal RR for both bradypnea (RR < 12) and trachypnea (RR > 20), which puts into operation through ATmega 328 to facilitate high level precision controlled action. The control system alongwith the sensory part occupies limited space in few centimeters with light weight. As a result, the electronics of the whole system can be easily mounted at the outer surface of the tube connected with the nasal mask. The scheme of such a portable and cost effective system is described in this present work.     

电容式MEMS器件模态频率的电学测试方法研究

针对电容式MEMS器件,提出了一种基于调制解调原理的模态频率测试方法,详细介绍了该测试方法的测试原理和测试系统的组成。利用Ansys对某插齿式微加速度计进行了模态仿真分析,分析得到的模态频率为3 941 Hz,利用该测试方法对该微加速度计进行模态频率测试,得到的测试结果为3 440Hz。仿真与测试得到的结果接近,验证了该测试方法的有效性,产生偏差的主要原因可能是制造过程中的加工误差。     

High-selectivity adjustable dual-band bandpass filter using a quantic-mode resonator

A novel adjustable dual-band bandpass filter using a quantic-mode resonator consisting of stepped impedance resonators (SIRs) and coplanar waveguide resonators (CPWRs) is proposed in this paper. The SIRs provide the lower passband with two transmission poles (TPs), while the upper passband is introduced by CPWRs and two TPs are obtained. Furthermore, an equivalent rectangular loop resonator (RLR) derived from the CPWRs is also introduced, providing another TP for the upper passband. One of the marked features of the filter is that the two passbands can be adjusted independently because of the independent resonant paths of different resonators. Besides, this filter has four transmission zeros (TZs), promising good stopband rejection and high band-to-band isolation. The measured results are consistent with the simulated results.

     

基于混合CPW和微带结构的超宽带滤波器

提出了一种新型的混合共面波导和微带结构的超宽带带通滤波器。通过将中间微带替换成交指耦合线,在下通带边缘产生一个传输零点,使得滤波器的选择性得到极大提升。此外,引入了耦合短路枝节以进一步提升其选择性和带外特性。实测结果表明,提出的滤波器具有不错的带内和带外性能。其具有陡峭的选择性,尺寸紧凑(0.49λg×0.47λg),插入损耗低,且上阻带宽。该滤波器的相对带宽达123%(2.75~11.55 GHz),回波损耗优于15 dB。并且,最终的加工实测结果和仿真结果基本一致。     

基于神经网络的耦合微带射频带通滤波器设计

给出了1/4波长耦合微带线射频带通滤波器设计的ADS仿真和神经网络方法.微带滤波器的3个重要参数线长L、线宽W、缝隙S以及频率freq做为神经网络的输入,反射系数S11和端口传输系数S21以及输入端电压驻波比VSWR1做为网络输出,神经网络训练结果和用电磁仿真软件ADS对滤波器的仿真结果基本一致.文中给出了采用改进粒子群优化(IPSO)算法思想改进的BP神经网络的训练算法.     

Control of bandwidth,resonant frequency,and modelling of bandpass filter using open stub resonator for K-band application

Microsystem Technologies - In this paper, we present the implementation of a new compact end coupled bandpass filter (BPF) in coplanar waveguide (CPW) technology. The proposed BPF is exposed with...     

Design and modeling of a frog-shape MEMS capacitive microphone using SOI technology

Microsystem Technologies - In this paper, a novel micro electro mechanical systems (MEMS) capacitive microphone is designed and modeled using SOI technology. We present static linear spring...     

Terahertz narrow bandstop, broad bandpass filter using double-layer S-shaped metamaterials

Abstract In this study, double-layer S-shaped metamaterials （MMs） are analyzed by terahertz time-domain spectroscopy. These materials exhibit narrow bandstop and broad bandpass transmission properties at both horizontal and vertical electric-field polarizations. A 117% increase in the unloaded quality factor is experimen- tally observed for these materials. The center frequency is approximately 0.45 THz, with a 3-dB bandwidth of 0.52 THz from 0.20 to 0.72 THz at normal incidence. The measured average insertion loss is 0.5 dB with a ripple of 1 dB. These results show that double-layer S-shaped MMs are effective in designing tunable terahertz devices.     

Superior performance area changing capacitive MEMS accelerometer employing additional lateral springs for low frequency applications

Microsystem Technologies - This paper introduces an effective and efficient microstructure of a differential area changing capacitive accelerometer to ensure low cross-axis sensitivity, high...     

Thermal drift analysis using a multiphysics model of bulk silicon MEMS capacitive accelerometer

An interpretation of the thermal drift of the bulk silicon MEMS capacitive accelerometer using multiphysics analysis is proposed in this paper. Stress, strain, electrostatics, thermal and structural interactions are simulated based on the finite element method. The thermal drift is generated by both the stiffness asymmetry of the U-springs of the structure and relative displacement caused by the mismatch in thermal expansion coefficients between the Pyrex glass substrate and heavily boron-doped silicon structure, neither of which is dispensable. Although the layout design is symmetrical, the asymmetric widths of the U-springs, which cause stiffness asymmetry, are observed by scanning electron microscopy. To achieve a fast and feasible simulation, we divide the model into two components with different configurations. During the simulation, boundary conditions are carefully set up according to the fabrication process. A series of experiments is designed to verify the result, including a temperature experiment from −40 to 100 °C and DC voltage polarity experiment. To verify the conclusion, a new layout design that gradually increases the width of the U-springs without changing any other dimension is simulated, fabricated, and tested. The simulation and experiment results are compared and discussed.     

High sensitivity and small size MEMS capacitive microphone using a novel slotted diaphragm

A novel single-chip microelectromechanical systems (MEMS) capacitive microphone with a slotted diaphragm for sound sensing is developed to minimize the microphone size and improve the sensitivity by decreasing the mechanical stiffness of the diaphragm. The behaviors of the microphones with clamped and slotted diaphragms are analyzed using the finite element method (FEM). According to the results, a clamped microphone with a 2.43 × 2.43 mm² diaphragm and a slotted one with a 1.5 × 1.5 mm² diaphragm have the same mechanical sensitivity, but the size of slotted microphone is at least 1.62 times smaller than clamped structure. The results also yield a sensitivity of 5.33 × 10⁻⁶ pF/Pa for the clamped and 3.87 × 10⁻⁵ pF/Pa for the slotted microphone with a 0.5 × 0.5 mm² diaphragm. The sensitivity of the slotted diaphragm is increased 7.27 times. The pull-in voltage of the clamped microphone is 105 V, and slotted one is 49 V. The pull-in voltage of the slotted microphone is about 53% decreased.     

Material selection methodology for radio frequency (RF) microelectromechanical (MEMS) capacitive shunt switch

Microsystem Technologies - This paper describes the process of selecting the most optimum Radio Frequency Micro- electro- mechanical-systems (RF-MEMS) switch design using Ashby’s methodology....