PZT 압전재료를 이용한 외팔보 구조의 에너지 수집기에 관한 연구

차두열,이수진,장성필,Cha, Doo-Yeol,Lee, Soo-Jin,Chang, Sung-Pil 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.5

Nowadays, the increasing demands upon mobile devices such as wireless sensor networks and the recent advent of low power electrical devices such as MEMS make such renewable power sources attractive. A vibration-driven MEMS lead zirconate titanate $Pb(Zr,Ti)O_3$ (PZT) cantilever device is developed for energy harvesting application. This paper presents a piezoelectric based energy harvester which is suitable for power generating from conventional vibration and has in providing energy for low power electron ic devices. The PZT cantilever is used d33 mode to get the electrical power. The PZT cantilever based energy harvester with the dimension of 7 mm${\times}$3 mm${\times}$0.03 mm is fabricated using micromachining technologies. This PZT cantilever has the mechanical resonance frequency with a 900 Hz. With these conditions, we get experimentally the 37 uW output power from this device with the application of 1g acceleration using the 900 Hz vibration. From this study, we show the feasibility of one of energy harvesting candidates using PZT based structure. This PZT energy harvester could be used for various applications such a batteryless micro sensors and micro power generators.

마이크로 머시닝 기술을 이용한 니켈기반의 압전 진동형 에너지 하베스터 제작

차두열,이재혁,장성필,Cha, Doo-Yeol,Lee, Jai-Hyuk,Chang, Sung-Pil 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.1

Owing to the rapid growth of mobile and electronic equipment miniaturization technology, the supply of micro mobile computing machine has been fast raised. Accordingly they have performed many researches on energy harvesting technology to provide promising power supply equipment to substitute existing batteries. In this paper, in order to have low resonance frequency for piezoelectric energy harvester, we have tried to make it larger than before by adopting nickel that has much higher density than silicon. We have applied it for our energy harvesting actuator instead of the existing silicon based actuator. Through such new concept and approach, we have designed energy harvesting device and made it personally by making with micromachining process. The energy harvester structure has a cantilever type and has a dimension of $10{\times}2.5{\times}0.1\;mm^3$ for length, width and thickness respectively. Its electrode type is formed by using Au/Ti of interdigitate d33 mode. The pattern size and gap size is 50 ${\mu}m$. Based on the measurement of the nickel-based piezoelectric energy harvester, it is found to have 778 Hz for a resonant frequency with no proof mass. In that resonance frequency we could get a maximum output power of 76 ${\mu}W$ at 4.8 $M{\Omega}$ being applied with 1 g acceleration.

광PCB를 위한 폴리머 저온 접합기술 연구

차두열,이재혁,장성필,Cha, Doo-Yeol,Lee, Jai-Hyuk,Chang, Sung-Pil 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.1

As the demands for the higher data transmission speed and capacity as well as integration density grow throughout the network, much works have being done in order to integrate the Electrical PCB with Optical PCB. However, one of the most troublesome problems in the commercial bonding process is to need the high temperature for the bonding. Due to the high temperature bonding process, lots of side problems are followed such as warpage and crack, etc. In this paper, we tried to develop the new bonding technology with low temperature around $100^{\circ}C$. As a result of this study, the PCB bonding technology with high bonding strength is demonstrated with the value of bonding strength from 7 to 8 MPa at the temperature of $100^{\circ}C$.

투자율이 높은 NiFe 코어를 이용한 마이크로 트랜스포머 제작

조세준,차두열,이재혁,이수진,장성필,Cho, Se-Jun,Cha, Doo-Yeol,Lee, Jai-Hyuk,Lee, Soo-Jin,Chang, Sung-Pil 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.3

Recently as the electronic devices are getting to be more and more smaller, transformers are needed to be micro fabricated using MEMS technology. In this paper transformers have been fabricated and measured by depositing insulation layer to reduce the loss of eddy current and in the middle core a high permeability permalloy was designed based on the turns ratio between primary coil and secondary coil which are 1:1 transformers. (the number of turns of primary coil and secondary coil: 3/3, 5/5, 7/7). The size of the transformers including ground shield are $1mm{\times}1.5mm$, $1mm{\times}1.95mm$, $1mm{\times}2.35mm$ respectively. The line width, pitch and the height of post are 50um. Based on the measured data from the micro fabricated transformers, the 3/3 turns in the primary coil and secondary coil showed the lowest insertion loss with 1.5 dB at 480 MHz and the 7/7 turns in the primary coil and secondary coil showed the highest insertion loss with 2.5 dB at 280 MHz. Also confirmed that the bandwidth goes up as the number of turns goes down. There was some difference between the actual measured data and the HFSS simulation result. It looks as if it is an error of the difference between oxidation of copper or the permeability of SU-8.

MEMS 감지기 및 작동기 박막의 기계적 특성연구

이흥식(Heung-Shik Lee),조종두(Chongdu Cho),장성필(Sung-Pil Chang) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.8

Mechanical characteristics of stainless steel have been studied as a diaphragm and a substrate material for the MEMS devices. In the study, a fabrication process for stainless steel micro machined devices keeps the membrane and substrate being at the environment of 8.65 ㎫ pressure and 175℃ for a half hour and then subsequently cooled to 25℃. The finite element method is adopted to investigate residual stresses formed in the process. Besides, out-of-plane deflections are calculated under pressures on the diaphragm.

LTCC 기판위에 MEMS 인덕터 특성 연구

박제영,차두열,김성태,강민석,김종희,장성필,Park, Je-Yung,Cha, Doo-Yeol,Kim, Sung-Tae,Kang, Min-Suk,Kim, Jong-Hee,Chang, Sung-Pil 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.12

Lots of integration work has been done in order to miniaturize the devices for communication. To do this work, one of key work is to get miniaturized inductor with high Q factor for RF circuitry. However, it is not easy to get high Q inductor with silicon based substrate in the range of GHz. Although silicon is well known for its good electrical and mechanical characteristics, silicon has many losses due to small resistivity and high permittivity in the range of high frequency. MEMS technology is a key technology to fabricate miniaturized devices and LTCC is one of good substrate materials in the range of high frequency due to its characteristics of high resistivity and low permittivity. Therefore, we proposed and studied to fabricate and analyze the inductor on the LTCC substrate with MEMS fabrication technology as the one of solutions to overcome this problem. We succeeded in fabricating and characterizing the high Q inductor on the LTCC substrate and then compared and analyzed the results of this inductor with that on a silicon and a glass substrate. The inductor on the LTCC substrate has larger Q factor value and inductance value than that on a silicon and a glass substrate. The values of Q factor with the LTCC substrate are 12 at 3 GHz, 33 at 6 GHz, 51 at 7 GHz and the values of inductance is 1.8, 1.5, 0.6 nH in the range of 5 GHz on the silicon, glass, and LTCC substrate, respectively.

전도성 에폭시를 이용한 직물 위에 구현된 건식 생체전위 전극의 연구

차두열,정정모,김덕수,양희준,최교상,최종명,장성필,Cha, Doo-Yeol,Jung, Jung-Mo,Kim, Deok-Su,Yang, Hee-Jun,Choi, Kyo-Sang,Choi, Jong-Myong,Chang, Sung-Pil 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.5

In this paper, micro dried bio-potential electrodes are demonstrated for sEMG (surface ElectroMyoGraphic) signal measurement using conductive epoxy on the textile fabric. Micro dried bio-potential electrodes on the textile fabric substrate have several advantages over the conventional wet/dry electrodes such as good feeling of wearing, possibility of extended-wearing due to the good ventilation. Also these electrodes on the textile fabric can easily apply to the curved skin surface. These electrodes are fabricated by the screen-printing process with the size of $1mm{\times}10mm$ and the resultant resistance of these electrodes have the average value of $0.4{\Omega}$. The conventional silver chloride electrode shows the average value of $0.3{\Omega}$. However, the electrode on the textile fabric are able to measure the sEMG signal without feeling of difference and this electrode shows the lower resistance of $1.03{\Omega}$ than conventional silver chloride electrode with $2.8{\Omega}$ in the condition of the very sharp curve surface (the radius of curvature is 40 mm).