To improve the performance of the micro-machined resonant pressure sensor and simplify its fabrication process, a
novel structure is proposed in which the boron diffused silicon (up to 15um thickness) and the bulk silicon are used as
the resonant beam and pressure membrane respectively. The structural parameters were optimized through FEM to
achieve the better sensitivity, and the relationships between the structural parameters and the sensitivity were
established. Moreover, the fabrication processes were discussed to increase the product rate and the pressure sensor with
the optimal structural parameters was fabricated by the bulk silicon MEMS processes. In order to enhance the signal of
the sensor and make the closed-looped control of the sensor easily, electromagnetic excitation and detection was applied.
However there is so high noise coming from the distributing capacitances between the diffused silicon layer and
electrodes that reduce the signal to noise ratio of the sensor. Through the analysis of the micro-structure of the sensor,
the asymmetrical excitation circuit was used to reduce the noise and then the detection circuit was designed for this
sensor. The resonator of the sensor was packaged in the low vacuum condition so that the high quality factor (Q) with
about 10000 can be achieved. Experimental tests were carried out for the sensor over the range of -80kPa to 100kPa, the
results show that the sensitivity of the sensor is about 20kHz/100kPa, the sensitivity is 0.01%F.S. and the nonlinearity is
A novel resonant pressure sensor structure is proposed to achieve better performance in quality factor (Q) and output
stability. Diffused silicon (15um) is used for the resonator, thus the resonator and the pressure diaphragm can be
fabricated on the same silicon substrate without bonding. A differential detection tri-resonator structure is adopted to
reduce the output drift and increase the sensitivity. To optimize the structure, a simplified 2-D model is set up for the
theoretical analysis. In addition, 3-D models of the 'H' style beam and the entire structure which is composed of a
diaphragm and three groups of beam respectively doubly supported by the anchors are constructed for the ansys-FEA
simulation. Through the theoretical analysis and the simulation, the structure parameters (beam length, beam thickness,
diaphragm thickness etc) are optimized. The natural frequency of the optimized model is 86.7 KHz, and the sensitivity is
19 KHz per 0.1MPa. The sensor is fabricated with the optimized parameters. The test experiments show that the results
basically correspond with the simulation results except the effect of the wet etching in the fabrication process. The
quality factor is 10000 in low vacuum, and the resolution is 1/10000.
A novel structure of micro-machined vibrating ring gyroscope (MVRG) with electromagnetic excitation and detection is
proposed, which consists of a ring and eight pairs of symmetric crab-leg suspension springs. The whole structure is
mirror-symmetric and centrosymmetric, providing the possibility to realize good mode-matching when the temperature
changes or acceleration shocks. The sensitivity of the MVRG is analyzed in detail, and the stability of the structure over
temperature and acceleration loads is analyzed using finite element analysis. The prototype of vibrating ring gyroscope is
successfully fabricated through bulk silicon processes which adopt only one silicon wafer without bonding process. The
gyroscope chip is assembled with SmCo permanent magnet and packaged in a metal case. The design of self-oscillation
closed-loop circuit is presented. FEA simulations show that the performance of the MVRG is stable over temperature
and acceleration loads and the structure can withstand shock loads up to 10000g without any special protection. Test
results show that the sensitivity of the MVRG is 8.9mv/°/s and the resolution is 0.05°/s with nonlinearity about 0.23% over a range of ±200°/sec.
This paper describes a resonant pressure sensor of a new structure which comprises two beams supported by only two rectangular piers. Both beams can be thermally excited into resonant vibration, whose resonant frequencies are differentially modulated by pressure loads, and the value of the applied pressure can then be obtained by measuring the resonant frequency of each beam. With thick silicon rich SiN film of low residual stress as mechanical vibrating beams, the sensor is fabricated from a single crystal silicon wafer, using porous silicon as a sacrificial layer. Computer simulation is carried out on temperature distribution, resonant frequency shift due to thermal stress, design of diaphragm geometry, and sensitivity of pressure measurement. Simulation results show that the novel structure improves the thermal stability and pressure sensitivity.
Numerical modeling of a SiN beam resonant pressure sensor is presented. The SiN beam is electrothermally excited and sensed by a piezoresistive thin film detector. In order to predict its exact performance and to optimize the design, the commercial FEA software is used to analyze the SiN beam resonant pressure sensor. Computer simulation is carried out on temperature distribution, resonant frequency shift due to thermal stress, effect of heater/detector elements on the natural resonance frequency, design of diaphragm geometry, and sensitivity of pressure measurement. The resonant pressure sensor has been fabricated using porous silicon sacrificial layer technology and measured both in vacuum and in air. There is a satisfactory agreement between computer simulation and experimental results.
This paper describes the mechanism of light addressable poteniometric sensors (LAPS) from the viewpoints of Semiconductor Physics, and introduces the fabrication of a multi-parameter LAPS chip. The MEMS technology is applied to produce a matrix of sensing regions on the wafer. By doing that, the cross talk among these regions is reduced, and the precision of the LAPS is increased. An IR-LED matrix is used as the light source, and the flow-injection method is used to input samples. The sensor system is compact and highly integrated. The measure and control system is composed of a personal computer, a lock-in amplifier, a potentiostat, a singlechip system, and an addressing circuit. Some experiments have been done with this device. The results show that this device is very promising for practical use.
FEA modeling of a thermally-excited silicon beam resonant pressure sensor is presented. The sensor consists of two bonded silicon chips, one with an etched beam and another with an etched diaphragm. FEA modeling is carried out on temperature distribution, resonant frequency shift due to thermal stress, effect of heater/detector elements on the natural resonance frequency, design of diaphragm geometry, and sensitivity of pressure measurement. The resonant pressure sensor samples are realized by silicon micromachining are measured. There is a satisfactory agreement between theory and experiments.
A new type pressure sensor based upon an electro-thermally driven and piezo-resistively sensed SiN-beam resonator is presented. A finite element analysis (FEA) method is involved to analyze the relationship between the excitation power, thermal stress, applied pressure and the resonant frequencies of the beam. The sensor is fabricated using silicon micro- machined technology and fusion bonding. Measurements yield a fundamental frequency of about 85 kHz and Q-factor of 1000 in air at atmospheric pressure, rising to over 40,000 in high vacuum (<0.01 Pa). A special close-loop detecting technology is employed to measure the response of the resonant frequency at different applied pressure loads. A 0 - 400 kPa sensor has a good linear frequency/pressure relationship. The span is about 10 kHz over the full pressure sweep, and the pressure sensitivity is about 23.8 Hz/kPa.
Modelling of a silicon resonator as a pressure sensor is presented. The resonator is electrothermally excited and the resonance frequency shift is detected by a piezoresistive thin film detector. Computer simulation using commercial MEMS software tool IntelliSuite<SUP>TM</SUP> is compared with analytical model. Various design aspects, such as the pressure sensitivity, electrothermal heating of vibrating beam, influence of detection current and damping effect are investigated. Silicon resonator sensor have been fabricated and measured. The characteristics predicted by computer simulation has been confirmed by experimental results.