• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.155-161
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• 2016

This paper proposes a novel fabrication method for a capacitive type micro-accelerometer with uniform nano-gap using photo-assisted electro-chemical etching. The sensitivity of the accelerometer should be improved while the electrodes between the inertial mass and the sensing comb should be narrowed. In this paper the nano-gap trench structure is fabricated using the photo-assisted electrochemical etching method. The sensor was designed and analysed using ANSYS simulator. The characteristics of the etching were observed according to the dc bias, the light intensity, the composition of the solution, the temperature of the solution, and the pattern pitch variation. The optimum etching conditions were dc bias of 2V, Blue LED of 20mA, 49wt% HF:DMF:D.I.Water=1:20:10, the pattern pitch of $20{\mu}m$. Uniform trench structure with width of 344nm and depth of $11.627{\mu}m$ are formed using the optimum condition.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1511-1513
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• 2003

본 논문에서는 polyimide를 감습물질로 한 정전용량형 정밀습도센서를 개발하여 실용화한 결과를 보고한다. 유리기판에 제작된 습도센서는 상대습도 11%RH${\sim}$96%RH 범위에서 다음과 같은 특성을 나타내었다. 감도; 0.5689 pF/%RH, 비선형성; 1.5%RH 미만, 히스테리시스; 약 1.5%RH, 감도특성의 온도 의존성; 0.08pF/$^{\circ}C$, 주파수 특성; 10, 100kHz에서 직선적.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1450-1454
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• 2007

A Contact-type Linear Encoder-like Capacitive Displacement Sensor (CLECDiS) has been developed to measure displacements at high accuracy within a long measurement range. In this paper, we have worked on improving the performance and reliability of the sensor. The performance increase can be done by introducing the smaller electrode patterns of $4{\mu}m$ width. In order to improve the reliability of the sensor we have changed the electrode layers from chrome-gold to chrome-gold-chrome and re-design its supporting structure. The newly-designed sensor is fabricated and tested to show that its sensitivity is $35pF/{\mu}m$, which implies that its resolution may be 0.36nm if SNR (Signal-to-Noise-Ratio) is 80.1dB. It is about ten times of that $(3.14pF/{\mu}m)$ of its previous version with 10${\mu}m$ electrodes. The total measurement range remains the same as the previous one; 15mm. The calibration experiments show its improved performance and reliability.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.102-113
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• 1995

일반적으로 단결정 실리콘은 거의 모든 전자소자의 재료로서 널리 사용되고 있으며 제조공정기술 또한 상당한 수준에 도달하고 있다. 최근에는 실리콘 자체의 우수한 압저항효과, 기계적 특성 그리고 반도체 제조공정을 이용한 미세가공기술인 마이크로머시닝을 이용하는 반도체 압력센서에 대한 연구가 활발히 진행되고 있다. 기계식 압력센서에 비해서 전기적 변화를 이용하는 반도체 압력센서에서는 소형, 저가격, 고신뢰성, 고감도, 다기능, 고분해, 고성능 및 집적화 등의 우수한 특성을 지니고 있다. 본고에서는 이러한 특성을 가지는 반도체 압력센서중 특히, 압저항형과 용량형 압력센서의 구조와 원리, 그리고 연구.개발동향 및 향후 전망에 관해서 기술하였다.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.19-27
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• 1993

Capacitive pressure sensor for low pressure measurements has been fabricated by using $n^{+}$ epitaxial layer electrochemical etching stop and glass-to-silicon electrostatic bonding technique. The sensor had hybrid configuration of a sensor chip, which consists of sensor capacitor and reference capacitor, and two output signal detection IC chips. A fabricated sensor, with a $1.0{\times}1.0 mm^{2}$ square size and a $10{\mu}m$ thick flat diaphragm, showed a 7.1 pF zero pressure capacitance, and 5.2 % F.S, sensitivity in 10 KPa pressure range. By using a capacitance to voltage converter, the thermal zero shift of 0.051 %F.S./$^{\circ}C$ and the thermal sensitivity shift of 0.12 %F.S./$^{\circ}C$ for temperature range of $5{\sim}45^{\circ}C$ were obtained.

• Journal of Sensor Science and Technology
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• v.7 no.2
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• pp.90-96
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• 1998

Non-contacting capacitive sensors, based on principle of the cross capacitor, for measuring small displacement less than $1.95{\pm}0.5\;mm$ have been fabricated and characterized. To overcome disadvantages of the existed capacitive sensors with 2-electrodes and 3-electrodes, the new sensor is consisted of 4-electrodes which are formed two electrode(high, low) and 2 guard electrodes on a sapphire plate with diameter 17 mm and thickness 0.7 mm, and are symmetrically situated with a constant gap of 0.2 mm between the electrodes. This sensor can be used for measuring both metallic and non-metallic target without ground connection, and is evaluated to the correlation coefficient of 0.9987 for the range of $1.95{\pm}0.5\;mm$ and that of 0.9995 for $1.95{\pm}0.25\;mm$ range.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.33-38
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• 2002

To establish the national standard of capacitance, four main electrodes of the cross capacitor which were evaluated to linearity and roundness less the $\pm 1 \mu m$ respectively have to be adjusted symmetrically in an inner cylinder. Four LM shafts with diameter of 5 mm were installed between main electrodes of the cross capacitor, and the electrodes were adjusted, as the first step, by means of the measured capacitance. In the second step, the symmetrical adjustment up to $\pm 1.2\mu m$ was performed by using a ball sensor, ball-type movable sensor, non-contacting capacitive sensor and upper guard sensor which were developed in this project.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.21-29
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• 2016

In this paper, we developed a flexible transparent capacitive pressure sensor which can recognize X and Y coordinates and the size of force simultaneously by sensing a change in electrical capacitance. The flexible transparent capacitive pressure sensor was composed of 3 layers which were top electrode, pressure sensing layer, and bottom electrode. Silver nanowire(Ag NW)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) hybrid film was used for top and bottom flexible transparent electrode. The fabricated capacitive pressure sensor had a total size of 5 inch, and was composed of 11 driving line and 19 sensing line channels. The electrical, optical properties of the Ag NW/PEDOT:PSS and capacitive pressure sensor were investigated respectively. The mechanical flexibility was also investigated by bending tests. Ag NW/PEDOT:PSS exhibited the sheet resistance of $44.1{\Omega}/square$, transmittance of 91.1%, and haze of 1.35%. Notably, the Ag NW/PEDOT:PSS hybrid electrode had a constant resistance change within a bending radius of 3 mm. The bending fatigue tests showed that the Ag NW/PEDOT:PSS could withstand 200,000 bending cycles which indicated the superior flexibility and durability of the hybrid electrode. The flexible transparent capacitive pressure sensor showed the transmittance of 84.1%, and haze of 3.56%. When the capacitive pressure sensor was pressed with the multiple 2 mm-diameter tips, it can well detect the force depending on the applied pressure. This indicated that the capacitive pressure sensor is a promising scheme for next generation flexible transparent touch screens which can provide multi-tasking capabilities through simultaneous multi-touch and multi-force sensing.

• Electrical & Electronic Materials
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• v.6 no.4
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• pp.339-346
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• 1993

정전결합 유동가스형 플라즈마 중합장치를 이용하여 여러가지 모노머에 대한 유기고분자 박막을 빗모양 전극위에 형성하고 이들 박막의 감습특성을 검토하기 위해 주파수범위를 60[kHz]-100[kHz]로 변화시켜 가면서 상대습도 20-90[%RH]범위에서 정전용량의 변화를 측정하였다. 상대습도가 증가함에 따라 정전용량은 일반적으로 증가했으며 방전조건중 방전전력이 낮을수록 그리고 중합시간이 짧을수록 정전용량의 증가폭이 크게 나타났다. 그리고 정전용량 측정시 박막에 인가한 전원의 주파수가 낮을수록 정전용량의 변화에 대한 선형성과 증가폭이 분명함을 알았다.

• Transactions of the KSME C: Technology and Education
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• v.2 no.1
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• pp.1-8
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• 2014

Recently vehicle development trend changes from machinery vehicle to the electrical and electronic devices. As well the electrical and electronic devices commercial vehicles are increasing more than machinery system. The capacitance fuel sensor is a sensor that, by measuring the capacitance value of fuel level sensor MCU operating for the final voltage value of the signal output. That is increasing durability and fuel measurement accuracy more than conventional ceramic resistor type. For Sensor software verification R-BENCH TOOL generated test case automatically. We make the programmable Capacitor board for test. And it was confirmed that more than 98% of the high reliability of the software.