Browsing by Author "Tsai, Chun-Yin"

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A NEW GAS BIO-SENSOR IN THE STRUCTURE OF A MICRO-MACHINED CLAMPED-CLAMPED INERTIAL BEAM AND ITS READOUT CIRCUIT
(2012)
Xue, Bing-Ze
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Chao, Paul C-P
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Lin, Bor-Shyh
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Tsai, Chun-Yin
;
Chen, Tsung-Lin
This study presents a novel gas bio-sensor in the form of a micro-machined resonator and its readout circuit. The resonator has the structure of a clamped-clamped beam with thermal actuation and piezo-resistive sensing that supports a plate capable of being attached with test gas molecules to detect gas concentration. The purpose of this study is to design and fabricate the micro-scaled inertial beam with its readout circuit in a system-on-chip package. The circuit includes a driver, a front-end converter, a feed-trough reduction unit, a square-wave converter and a phase detector. In the process of signal reading,, the sensor is first driven by a DDS module and power amplifier, and then sense the vibrations by piezo-resistivity. The piezo-resistivity is detected by a Wheatstone bridge circuits. The carried signal of modulation is processed by a Wheatstone bridge circuits. An instrumentation amplifier adjusts the gain to the appropriate amplitude. The circuit with reduction on feed-through noise increases the SNR. Square wave conversion circuit and PFD process the signal and the driver reference signal to detect phase difference. The data of phase difference is counted into a microcontroller dsPIC4011 and then the data being transmitted to the computer by RS232 to a USB adapter. Finally, the whole circuit is implemented by using TSMC 0.35 2P4M process and one-step post-processing.
A new hybrid fabrication process for a high sensitivity MEMS microphone
(2013-09-01)
Chao, Paul C. -P.
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Tsai, Chun-Yin
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Chiu, Chi-Wei
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Tsai, Che-Hung
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Tu, Tse-Yi
A novel multi-layer stacking capacitive type microphone is designed in this study based on theoretical analysis and numerical simulations, while fabricated via two standard stable silicon-based MEMS processes-PolyMUMPs and SOIMUMPs. The adoption of two standardized processes helps greatly to increase yield rate. The sensitivity of the microphone is first determined by an analytical model based on an equivalent circuit, which is followed by finite element (FEM) analyses on the capacitance value, static pull-in voltage and dynamic characteristics. Based on the developed analytical model, varied dimensions of the microphone are optimized and then the performance is validated by analytical simulations. In the next step, micro-fabrication of the microphone is accomplished using two standard processes, PolyMUMPs and SOIMUMPs provided by MEMSCAP. Experiments are conducted to acquire the information of pull-in voltage for safe operation and frequency response in sensitivity for performance evaluation. In the static case, experimental results show a good agreement with the analytical results with 90 Mpa residual stress assumed. As for dynamic validation, the frequency response is measured in an anechoic room adopting the exciting frequency as the audible range from 100-10 kHz. The measured sensitivity is as around 0.78 and 1.7 mV/Pa from 100 to 10 kHz, under the biases of 2 and 4.5 V, respectively. Within the audible frequency range, the proposed device maintains the loss as less as 2.7 dB (ref. to V/Pa), under 3 dB-the commonly acceptable drop within audible frequency range.
A Novel Gas Sensor in the Form of Micro-machined Resonator and its Readout Circuit
(2011)
Xue, Bing-Ze
;
Chao, Paul C. -P.
;
Lin, Bor-Shyh
;
Tsai, Chun-Yin
;
Chen, Tsung-Lin
This study presents a novel gas sensor in the form of a micro-machined resonator and its readout circuit. The resonator has the structure of clamped-clamped beams with thermal actuation and piezo-resistive sensing that supports a plate capable of being attached with test gas molecules to detect gas concentration. The purpose of this study was to design a new gas sensor readout system for a clamped-clamped beam resonator with thermal actuation and piezo-resistive sensing and also presents a new approach to reject the feed-through noise. The sensor is driven by a DDS module and power amplifier, and then sense the vibrations by piezo-resistivity. The piezo-resistivity is detected by a Wheatstone bridge circuits. The carried signal of modulation is set in Wheatstone bridge circuits. An instrumentation amplifier adjusts the gain to the appropriate amplitude. The circuit with reduction on feed-through noise increases the SNR. Square wave conversion circuit and PFD process the signal and the driver reference signal to detect phase difference. The data of phase difference is counted into a microcontroller dsPIC4011 and then the data being transmitted to the computer by RS232 to a USB adapter. Finally, the whole circuit is implemented by using TSMC 0.35 mu m 2P4M process and one-step post-processing.
An optimal design of thermal-actuated and piezoresistive-sensed CMOS-MEMS resonant sensor
(2013-11-01)
Wang, Chun-Chieh
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Tsai, Chun-Yin
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Chen, Tsung-Lin
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Liao, Sin-Hao
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機械工程學系
This paper proposes an optimal design of the thermal-actuated, piezoresistive-sensed resonator fabricated by a foundry-provided CMOS-MEMS process. The optimal design is achieved both by quantitatively comparing the mechanical properties of different composite films as well as by deriving an analytical model for determining the device dimensions. The analytical model includes a stress model of an asymmetric mechanical structure and a piezoresistivity model of the heavily doped, n-type polysilicon film. The analytical model predicts that the optimal length of the displacement sensor is 200 mu m when the thermal actuator is 200 mu m in length and the absorption plate is 100 mu m in length. Additionally, the model predicts the resistivity of the polysilicon film of (6.8 +/- 2.2) m Omega cm and the gauge factor of (6.8 +/- 2.9) when the grain size is (250 +/- 100) nm. Experimental results agree well with simulation results. Experimental data show that the resonant frequency of the device is 80.06 kHz and shifts to 79.8 kHz when a brick of Pt mass is deposited on the resonator. The mass of the Pt estimated from the frequency shift is 4.5419 x 10(-12) kg, while estimated from the measured dimension is 4.4204 x 10(-12) kg. Sensitivity of the resonant sensor is calculated to be 1.8 x 10(2) Hz ng(-1). Experimental results further show that the polysilicon film used in the experiments has a grain size of (241 +/- 105) nm, an average gauge factor of 5.56 and average resistivity of 5.5 m Omega cm.
Design and fabrication of a CMOS MEMS logic gate
(2011)
Tsai, Chun-Yin
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Chen, Tsung-Lin
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Liao, Hsin-Hao
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Lin, Chen-Fu
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Juang, Ying-Zong
This study aims to develop a novel CMOS-MEMS logic gate via commercially available CMOS process (TSMC, 2P4M (R)). Compared to existing CMOS MEMS designs, which uses foundry processes, the proposed design imposes several new challenges including: carrying two voltage levels on a non-warping suspended plate, metal-to-metal contact, and etc. Different combinations of oxide-metal films and post-CMOS process are investigated to achieve a non-warping suspended structure layer. And different wet etchants are investigated to remove sacrificial layers without attacking structure layers and features. In a prototype design, the selected structure layer is metal-3 and oxide film; the device is released using AD-10 and titanium etchant; the device is 250 mu m long, 100 mu m wide, and 1.5 mu m gap. The experimental results show that the suspended plate slightly curls down 0.485 mu m. This device can be actuated by 10/0 V with a moving distance 50nm. The resonant frequency is measured at 36 kHz. Due to the damage of the tungsten plugs, the logic function can only be verified by its mechanical movements instead of electrical readouts for now.
Design and fabrication of MEMS logic gates
(2008-04-01)
Tsai, Chun-Yin
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Kuo, Wei-Ting
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Lin, Chi-Bao
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Chen, Tsung-Lin
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機械工程學系
This paper presents a novel design of MEMS logic gate that can perform Boolean algebra the same as logic devices that are composed of solid-state transistors. This MEMS logic gate design inherits all the advantages from MEMS switches and thus is expected to have more applications than MEMS switches. One unique feature of this device is that it can perform either NAND gate or NOR gate functions with the same mechanical structure but with different electrical interconnects. In a prototype design, the device is 250 mu m long, 100 mu m wide and has 1 mu m gap. The experimental results show that this device can operate at 10/0 V and achieve the proposed logic functions. The resonant frequency of the device is measured roughly at 30 kHz. Due to no metal-to-metal contact in the current device, the logic functions of the design are verified through observations and video taping.
Design, fabrication and calibration of a novel MEMS logic gate
(2010-09-01)
Tsai, Chun-Yin
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Chen, Tsung-Lin
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機械工程學系
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Department of Mechanical Engineering
This paper presents the design, fabrication and calibration of a novel MEMS logic gate that can perform Boolean algebra as well as logic devices composed of solid-state transistors. Unlike existing designs, the proposed design can perform either NAND gate or NOR gate functions using the same mechanical structure, but different electrical interconnects. The proposed design imposes three requirements on the fabrication process: two voltage levels carried on a suspended plate, metal-to-metal contact between shuttle electrodes and fixed electrodes, and a low process temperature (<300 degrees C). To fulfill these requirements, the residual stress in the fabricated device is substantial which could impair the functionality of the device. Therefore, a novel in situ film stress calibration method is developed to assist the development of the fabrication process. In a prototype design, the fabricated device is 250 mu m long, 100 mu m wide and of 3.97 mu m gap. Experimental results show that the device can operate at 25/-25 V and 100 Hz, and achieve the proposed logic functions. In addition, several properties of this device are experimentally evaluated, including power consumption, on/off resistance, lifetime and resonant frequency.