CMUTS in permanent contact operation for high output pressure

Min Chieh Ho, Maik Hoffmann, Alexander Unger, Kwan Kyu Park, Mario Kupnik, Butrus T. Khuri-Yakub

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We present the operation of capacitive micromachined ultrasonic transducers (CMUTs) in permanent contact mode as an efficient transducer. The gap height of our transducers is chosen to be slightly smaller than the static deflection of the plate due to the pressure difference between the ambient and the vacuum cavity. Thus, the plates are in contact with the bottom of the cavities even with no dc bias applied. The devices were fabricated based on the thick box process. High-temperature assisted direct wafer bonding technique was used to fabricate devices with such large cell size (radii ~ 2000 μm) featuring low frequencies ~100 - 150 kHz. Extensive acoustic characterization was performed to demonstrate the behavior of such CMUTs in terms of displacement profile, output pressure and acoustic pitch-catch response. A maximum sound pressure of ~145 dB (SPL) at the transducer surface is measured at 240 V dc and 10V ac with 100 cycles of burst signal. This is a great improvement from conventional CMUTs (with deeper gap height, operating at 55 kHz), which requires 350 V dc and 200 V ac in order to achieve an output pressure of 129 dB (SPL) at the transducer surface. The results presented in this paper demonstrate that operating CMUTs in permanent contact mode indeed enhances the device output pressure, and provides a good candidate for efficient ultrasonic transducers.

Original languageEnglish
Title of host publicationAdvanced Fabrication and Manufacturing; Emerging Technology Frontiers; Energy, Health and Water- Applications of Nano-, Micro- and Mini-Scale Devices; MEMS and NEMS; Technology Update Talks; Thermal Management Using Micro Channels, Jets, Sprays
PublisherAmerican Society of Mechanical Engineers
Volume3
ISBN (Electronic)9780791856901
DOIs
StatePublished - 2015 Jan 1
EventASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2015, collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels - San Francisco, United States
Duration: 2015 Jul 62015 Jul 9

Other

OtherASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2015, collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels
CountryUnited States
CitySan Francisco
Period15/07/615/07/9

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    Ho, M. C., Hoffmann, M., Unger, A., Park, K. K., Kupnik, M., & Khuri-Yakub, B. T. (2015). CMUTS in permanent contact operation for high output pressure. In Advanced Fabrication and Manufacturing; Emerging Technology Frontiers; Energy, Health and Water- Applications of Nano-, Micro- and Mini-Scale Devices; MEMS and NEMS; Technology Update Talks; Thermal Management Using Micro Channels, Jets, Sprays (Vol. 3). American Society of Mechanical Engineers. https://doi.org/10.1115/IPACK2015-48733