• 비파괴검사학회지
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• 제34권1호
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• pp.77-84
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• 2014

• The Journal of the Acoustical Society of Korea
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• 제20권3E호
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• pp.31-37
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• 2001

Finite element model of a cMUT is constructed using the commercial code ANSYS to analyze the cross talk mechanism. Calculation results of the complex load impedance seen by single capacitor cells are presented, and then followed by a calculation of the plane wave real load impedance seen by a parallel combination of many cells that are used to make a transducer. Cross talk between 1-D array elements is found to be due to two main sources: coupling through a Stoneley wave propagating at the transducer-water interface and coupling through Lamb waves propagating in the substrate. To reduce the cross talk level, the effect of various structural variations of the substrate are investigated, which include a change of its thickness and etched trenches or polymer walls between array elements.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권1호
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• pp.17-23
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• 2005

This paper describes the simulation of a micromachined dome-shaped-diaphragm acoustic transducer built on a $1.5{\mu}m$ thick silicon nitride diaphragm ($2,000{\mu}m$ in radius, with a circular clamped boundary on a silicon substrate) with electrodes and piezoelectric ZnO film in a silicon substrate. Finite element analysis with ANSYS 5.6 has been performed to analyze the static and dynamic behaviors of the transducer under both pressure and voltage loadings.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.385-386
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• 2010

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.347-351
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• 1997

A micromachined piezoelectic cantilever transducer,which works both as a microphone and as a microspeaker,has been fabricated and tested. The 2000*2000*3.mu.m .sap2. cantilever has oxide(ZnO)piezoelectric thin film on a supporting layer of low-pressure chemical-vapor-deposited(LPCVD)low-stress siliconnitride. A highlight of the fabrication process which may also be relevant for other micromachined stuctures is the technique for producing a flat,multilayer cantilever. The measured microphone sensitivity is fairly constant at 2 mV/.mu.bar in the low frequency range and rise to 20 mV/.mu.bar at the lowest resonant frequency of 890 Hz. The 2 mV/.mu.bar sensitivity is the highest report to data for a microphone with a micromachined diaphragm. When measured into a 2 cm/sap3 coupler with 4V (zero-park)drive,the microspeaker output sound pressure level(SPL) is 75 dB at 890 Hz. It increases to approximately 100dB SPL at 4.8kHz with 6V(zero-park)drive. The measured microphone frequency response agrees well with the results of an ABAQUS simulation.

• 비파괴검사학회지
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• 제25권6호
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• pp.446-450
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• 2005

We have built a spherically focused, not using acoustic mirrors, capacitive micromachined air-coupled ultrasonic transducer. A flexible backplate of a copper/polyimide backplate is used, permitting it to conform to a spherically shaped substrate. The backplate is patterned with $40-{\mu}m$ depressions having $80-{\mu}m$ center-to-center spacing. A $6-{\mu}m$ thick aluminized Mylar film completing the transducer is deformed to allow it to conform to the spherical backplate. The device's frequency spectrum is centered at 805kHz with -6dB points at 440 and 1210kHz.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.162-162
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• 2007

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2434-2440
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• 2018

A new type of piezoelectric micromachined ultrasonic transducer (pMUT) with high resonant frequency was developed by using a thin lead zirconate titanate (PZT) as an insulation layer on a floating $10{\mu}m$ silicon membrane. The PZT insulation layer facilitated acoustic impedance matching at active pMUT, leading to a high performance in the acoustic conversion property compared with the transducer using $SiO_2$ insulation layer. The fabricated ultrasonic devices were wirelessly measured by connecting two identical acoustic transducers to two separate ports in a single network analyzer simultaneously. The acoustic wave emitted from a transducer induced a $3.16{\mu}W$ on the other side of the transducer at a distance of 2 cm. The transducer performances in terms of device diameters, PZT thickness, annealings, and different DC polings, etc. were investigated. COMSOL simulation was also performed to predict the device performances prior to fabrication. Based on the COMSOL simulation, the device was fabricated and the results were compared.

• 한국음향학회지
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• 제39권2호
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• pp.87-97
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• 2020

본 논문에서는 공기 중 광대역 초음파 방사용 압전 박막 기반 초소형 초음파 트랜스듀서(piezoelectric Micro-machined Ultrasonic Transducer, pMUT)의 설계 연구가 진행되었다. 하나의 트랜스듀서로 광대역을 달성하는 방법 중 하나는 다공진 시스템으로 설계하는 것이다. 새로운 pMUT은 박막 구조의 앞면과 뒷면에 적절한 음향 구조를 추가하여 다공진 시스템을 구현하도록 설계되었다. 박막 앞쪽은 도파관 구조로 모델링된 방사 파트로, 박막 뒷쪽은 음향 공동으로 모델링된 패키징 파트로 이루어져있다. 박막 파트, 방사 파트, 패키징 파트로 구성된 새로운 pMUT은 집중 변수 모델로 설계되었으며, 최종적으로 유한요소해석으로 검증되었다. 최종 설계된 pMUT은 102 kHz ~ 132 kHz (-3 dB)의 주파수 대역을 달성하였다.

• 비파괴검사학회지
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• 제24권5호
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• pp.487-493
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• 2004

본 연구는 고효율 비접촉 초음파 송수신이 가능한 미세가공 정전용량형 초음파 탐촉자(cMUT)를 개발하기 위한 기초연구로 수행되었다. cMUT의 주요 구성요소인 미세 진동 막의 거동-총진 주파수, 막 변위, 막 붕괴 변위, 막 붕괴전압-을 이론적인 해석과 유한요소해석을 이용하여 분석하였다. 진동 막의 두께와 크기, 희생층 두께, 전극의 두께와 크기 등과 같은 cMUT의 설계인자를 검토하였다. 분석결과 진동 막의 공진주파수는 진동 막의 두께가 증가함에 따라 증가하였으며 직경에 따라서는 감소하였다. 직류 바이어스 전압이 증가함에 따라 진동 막의 변위는 증가하였으며 진동 막의 붕괴전압을 분석하였다.