• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.2
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• pp.116-122
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• 2004

A micromachined self-exited piezoelectric cantilever has been fabricated using PZT(52/48) thin film. For the application to biosensor using antigen-antibody interaction, electromechanical properties such as resonant frequency and quality factor of micromachined piezoelectric cantilever were important factors. Electromechanical properties and resonant behaviors of microfabricated cantilever were simulated by FEA (Finite Element Analysis) using Coventorware$^{TM}$2003. And these characterization of microcantilever were measured by using LDV(Laser Doppler Vibrometer) to compare with FEA data. We present the resonant frequency shift of micromachined piezoelectric cantilevers due to combination of mass loading and change of spring constant by gold deposition. Experimental mass sensitivities of microcantilever were characterized by Au deposition on the backside of microcantilever. Mass sensitivities with $100{\times}300$ ${\mu}{\textrm}{m}$ dimension cantilever from simulation and experimental were 5.56 Hz/ng and 16.8 Hz/ng respectively.y.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.153-153
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• 2002

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.487-493
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• 2011

Alpha fetoprotein(AFP), which is serological marker for hepatocellular carcinoma, was quantitatively measured by its normal concentration, 10 ng/ml, with a label-free piezoelectric microcantilever mass sensor. The principle of detection is based on changes in the resonant frequency of the piezoelectric microcantilever before and after target molecules are attached to it, and its resonant frequency is measured electrically using a conductance spectrum. The resonant frequency of the developed sensor is approximately 1.34 MHz and the mass sensitivity is approximately 175 Hz/pg. The sensor has high reliability as mass sensor by reducing the effect of surface stress on resonant frequency due to attached proteins. 'Dip and dry' technique was used to react the sensor with reagents for immobilizing AFP antibody on the sensor and detecting AFP antigen. The measured mass of the detected AFP antigen was 6.02 pg at the concentration of 10 ng/ml, and 10.67 pg at 50 ng/ml when the immunoreaction time was 10 min.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.493-494
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• 2012

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.54.2-54
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• 2003

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.177-180
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• 2002

Thickness dependence of crystallographic orientation of diol based sol-gel derived PZT(52/48) films on dielectric and piezoelectric properties was investigated The thickness of each layer by one time spinning was about 0.2 $\mu\textrm{m}$, and crack-free films was successfully deposited on 4 inches Pt/Ti/SiO$_2$/Si substrates by 0.5 mol solutions in the range from 0.2 $\mu\textrm{m}$ to 3.8 $\mu\textrm{m}$. Excellent P-E hysteresis curves were achieved without pores or any defects between interlayers. As the thickness increased , the (111) preferred orientation disappeared from 1$\mu\textrm{m}$ to 3 $\mu\textrm{m}$ region, and the orientation of films became random above 3 $\mu\textrm{m}$. Dielectric constants and longitudinal piezoelectric coefficient d$\_$33/, measured by pneumatic method were saturated around the value of about 1400 and 300 pC/N respectively above the thickness of 0.8 7m. A micromachined piezoelectric cantilever have been fabricated using 0.8 $\mu\textrm{m}$ thickness PZT (52/48) films. PZT films were prepared on Si/SiN$\_$x/SiO$_2$/Ta/Pt substrate and fabricated unimorph cantilever consist of a 0.8 fm thick PZT layer on a SiNx elastic supporting layer, which becomes vibration when ac voltage is applied to the piezoelectric layer. The dielectric constant (at 100 kHz) and remanent polarization of PZT films were 1050 and 25 ${\mu}$C/$\textrm{cm}^2$, respectively. Electromechanical characteristics of the micromachined PZT cantilever in air with 200-600 $\mu\textrm{m}$ lengths are discussed in this presentation.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.75-75
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• 2003

본 연구에서는 대기 중 극 미량으로 존재하는 환경 유해 가스 성분을 검출할 수 있는 미세 소자로의 응용을 위해 마이크로 칸티레버를 제작하고 가스 센서로의 활용 가능성을 검토하였다. 마이크로 칸티레버는 크게 구동층 캐패시터로서 대표적인 압전 재료인 Pb(Zr,Ti)O$_3$ (PZT)를 사용하고 SiNx 박막을 지지층으로 하는 형태로 제작되었다. 제작된 마이크로 칸티레버는 치수 및 형상에 따라 17~29 KHz 의 기본 공진 주파수 값을 나타내었다. Electron beam evaporator를 이용한 copper (Cu) 박막의 단계적인 증착을 통해 칸티 레버 표면에 질량을 증가시키고 그에 따른 마이크로 칸티레버의 공진주파수 변화를 관찰한 결과 질량 증가에 대해 34 Hz/ng의 선형적인 주파수 감소를 나타내었으며, 이로부터 694.4 $\textrm{cm}^2$/g 의 gravimetric sensitivity factor를 얼을 수 있었다. 마이크로칸티레버의 가스 감지능력 시험을 위해 가스 흡착층으로 일차 알콜류의 vapor를 흡착 하는 것으로 보고된 poly methyl metacrytate (PMMA)를 마이크로 칸티레버 표면에 코팅하였다. 마이크로칸티 레버의 기본 공진 주파수 및 PMMA 흡착층 형성과 가스의 흡착에 따른 주파수 변화는 마이크로 칸티 레버로부터 의 전기적 신호를 이용하는 복소 임피던스 분석에 의해 측정되었다. PMMA가 코팅된 마이크로 칸티레버는 ethanol 및 methanol vapor 의 농도가 증가함에 따라 선형적인 공진주파수 감소를 나타내었으며, methanol vapor 의 경우 0.06 Hz/ppm 의 가스 검출 감도를 얻을 수 있었다.