The research on frequency measurement for the designed resonator used to detect infrared radiation by means of tracking the change in resonance frequency of the resonator with temperature attributed to the infrared radiation from targets is presented in this paper. The research provides the basis for the integrated design of the uncooled infrared MEMS resonance structure and its measuring circuits.
For a designed sensor with bi-material resonator which is used to detect infrared (IR) radiation by means of tracking the change in resonance frequency of the resonator with temperature attributed to the IR radiation from targets, in accordance with electromagnetic theory, the relationship between the electrical driving force exerted on the resonator and the exciting voltage applied across two electrodes of the capacitor in the sensor is presented. According to vibration theory, the dependence of the driving force on the exciting voltage is analyzed. The result of analysis is used to guide the vibration mode and frequency-amplitude response simulations of the resonator. The simulation value is approximately equal to the measured value, which demonstrates that the analysis result is effective and practicable.
A resonant infrared thermal sensor with high sensitivity, whose sensing element is a bimaterial structure with thermal expansion mismatch effect, is presented. The sensor detects infrared radiation by means of tracking the change in resonance frequency of the bimaterial structure with temperature attributed to the infrared radiation from targets. The bimaterial structure is able to amplify the change in resonance frequency compared with a single material structure for a certain mode of vibration. In accordance with the vibration theory and the design principle of an infrared thermal detector, the resonant sensor, which can be arranged in an array, is designed. The simulation results, by using finite element analysis, demonstrate that the dependence of resonance frequency on temperature of the designed structure achieves 1 Hz/10 mK. An array of 6×6 resonant thermal sensors is fabricated by using microelectronics processes that are compatible with integrated circuit fabrication technology. The frequency variation corresponding to the temperature shift is obtained by electrical measurement.
A resonant infrared thermal sensor with high sensitivity, whose sensing element is a bi-material structure with thermal
expansion mismatch effect, is presented in this paper. The sensor detects infrared radiation by means of tracking the
change in resonance frequency of the bi-material structure with temperature change attributed to the infrared radiation
from targets. The bi-material structure can amplify the change in resonance frequency compared to a single material
sensing structure. In accordance with the theory of vibration mechanics and design principle of infrared thermal detector,
the bi-material resonant sensor by means of which an array can be achieved is designed. The simulation results, by
ANSYS software analysis based on multi-layer shell finite element, demonstrate that the dependence of resonance
frequency on temperature of the designed sensing structure achieves 1Hz/0.01°C. A microarray with 6×6 resonant
infrared sensors is fabricated based on microelectronics processes being compatible with integrated circuit fabrication
technology. The frequency variation corresponding to the temperature shift can be obtained by electrical measurement.
This paper will focus on Au/Si eutectic bonding technology. We have set up and improved some MEMS models concerning this technique for discussion. Annealing temperature on bonding was also taken into consideration. Since hydrophilic surface has a large number of —OH groups, which can make two wafers in contact, we derive a hydrophilic surface from dipping the wafer in H2O /H202/NH4OH solution. Especially we use MEMS models with ANSYS to simulate and guide the fabrication of MEMS device. Furthermore, we have improved MEMS structure. Because its bonding temperature, voltage and pressure are low, by using the following technique we could get high density and more reliable MEMS device. We also have used this technology to fabricate gyroscope and some other MEMS devices. Classical Au/Si fusion bonding at 1000°C, and anodic at 450°C is not a commercially feasible process. We achieved AU/Si eutectic bonding technology for gyroscope and other MEMS device manufacture.
A novel micromechanical variable optical attenuator (VOA) for single mode fibers based on MEMS is presented in this paper. The fabrication of the micromechanical VOA combines the processes of wafer bonding and deep reactive ion etch (RIE) that presents a simply procedure of MEMS manufacturing. The VOA consists of a slope anchor and a beam with a shutter, in which the beam is laterally driven by electrostatic actuator. It is important to design and optimize the slope anchor to produce large shutter displacement with low driving voltage. In this design, the shutterí»s displacement and beam diffraction is computed to estimate the device performance as applied voltage changed. We conclude that, based on the status of current fabrication technologies, the proposed design is feasible to be implemented and shows a good candidate for the power management in complex WDM networks.
This paper presents the design and simulation of a novel acceleration sensor with high accuracy and overload ability. A super-stable structure with quad-beams , which has highly symmetric structure has been designed, and this help to eliminate the errors caused by the change of the dimensions and position of the piezoresistors in structure. At the same time, this structure induces films between the beams to reduce the cross-axis sensitivity. Some holes are made in the films to reduce the vertical rigidity. Thus, the films have little effect on the sensitivity. Besides, the sandwich structure is adopted In this device , the damping of the device is controlled by adjusting the clearances between the caps and the seismic mass ,which can obtain the large bandwidth and good frequency response. The bumps are made on two caps to get high overload ability. The piezoresistors are covered with metal layer to improve the electric performance. The structure made beneficial to the high resolution, low cross-axis sensitivity, high overload and good electric performance of the device.
A new LIGA-like microfabrication technique was developed by present authors. DEM (deepetching, electroforming and microreplication) is the abbreviation of three main process steps in this new microfabrication technique. In contrast to LIGA technique, DEM technique has the advantages of lower cost and shorter process period. Microfluidic systems like plastic capillary electrophoresis chips, micro flowmeters and three-dimensional DNA chips were developed using DEM technique. DEM technique offers a new way for fabrication of MEMS and MOEMS components.
Multiplefield coupling is a typical characteristic of most mechanical structures in microelectromechanical system (MEMS), that involves the effects due to mechanical, electrostatic, magnetic, thermal actions, etc. Dynamic behaviors of the microstructures in those fields are of importance to estimate the design and manufacturing of the microsystem. In this paper, electromechanical analyses of some microstructures are presented based on a combination of boundary element method (BEM) and finite element method (FEM), to show the hybrid numerical technique not only useful to analyze the flexible deformation of the structures under electrostatic forces, but also important to evaluate the parameter variations of the electronic fields as the movement of the mechanical structures in those structronic systems. The simulation procedure is verified by both analytical solutions of some examples and experimental results of some microstructures driven by electrostatic field, in which the mechanical parameters such as the divergence of the deflection solution is related to the electrical characteristic such as the critical voltages of the electrostatic forces. Based on the structures involved in a laterally vibratory polysilicon gyroscope fabricated in our institute, the control equations of microgyroscope dynamics are presented, from that the response simulations of the microgyro are performed with the changes of the characteristic parameters, such as resonant frequency, quality factors, frequency disturbance, etc. Those results are useful for the optimal design of the structronic systems and the quality evaluation of the microprocessing, which are related to the rate measurement sensitivity and the output stability of the microsystem.
Molecular Radar (MR) is a new method to detect biological processes in living cells at the level of molecular, it is also the newest means to get intracellular information. In this paper we study the effect of morphine on PC12 cells using MR. The results show that the effect of morphine on PC12 cells is time- and concentration-dependent. Morphine treating for short time induces the increase and fluctuation of intracellular (CA2+), while morphine treating for long time induces chromatin condensation, loss of mitochondria membrane potential apoptosis.
A monolithic micromachined inertial measurement unit (IMU), which combines three-degree-of-freedom gyroscope and a three-degree-of-freedom accelerometer, is attractive for navigation and guidance. A micromachined gyroscope generally works in a vacuum package to archive a high resolution. By contraries, a package of an accelerometer should provide proper dumping to optimize dynamic response. It is very difficult to fulfill two different package demands in one chip by using conventional package technology. We developed wafer-level silicon cap package technology to solve the problem. The gyroscope is completely sealed in a vacuum silicon cavity by anodic bonding in vacuum. The accelerometer is package din another silicon cavity, but different from the gyroscope, a 'bypass hole' is fabricated in the wall of the cavity. Using this technique, the accelerometer can operate in an air ambient, the damping is controlled by optimizing structure design of accelerometer and change the size of the bypass hole. Consequently, demands of package for both accelerometer and gyroscope are fulfilled. Besides, the silicon cap can protect fragile mechanical structures during post-releasing processing, such as dicing, mounting and wire bonding. Consequently, after the silicon cap is formed, the MEMS wafer can be treated as a common IC wafer. These structures were fabricated with wafer bonding and ICP deep etching technologies, but can be also fabricated by other micromachining technologies.
DEM technique developed by present authors is a new 3D micro fabrication technique for non-silicon materials such as metals, plastics and ceramics. In comparison with LIGA technique, it does not need expensive synchrotron radiation source and x-ray masks. DEM technique has both advantages of bulk silicon micro fabrication technique and LIGA technique. In the present research, we obtained metallic mold insert with structure depth of 180 micrometers and aspect ratio more than 20. A successful development of DEm technique opens a new way for 3D micro fabrication of non-silicon materials.
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