The long-term reliability of pre-charged CMUTs for the powering of deep implanted devices

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Recently, focused ultrasound has been proposed to power deeply implanted medical devices. Almost exclusively, lead zirconate titanate (PZT) transducers are used to convert acoustic energy into electrical energy. Unfortunately, these lead containing devices cannot be hermetically encapsulated since that would block the ultrasound. We propose the use of biocompatible Capacitive Micromachined Ultrasonic Transducer (CMUT) elements to replace traditional PZT transducers. In addition, to eliminate the external bias voltage, we introduced a charge trapping Al2O3 layer inside the CMUT to create a built-in bias voltage. These devices can be pre-charged and used as a receiver for US power. In this work, the viability of charged CMUTs to power deep implants was explored by investigating the effect of the charging parameters and by performing Accelerated Lifetime Tests (ALT). The estimated lifetime at body temperature ranges between 2.5 to 3.5 years at body temperature, which significantly depends on the charging parameters.
Original languageEnglish
Title of host publication2021 IEEE International Ultrasonics Symposium (IUS)
Subtitle of host publicationProceedings
Place of PublicationPiscataway
Number of pages4
ISBN (Electronic)978-1-6654-0355-9
ISBN (Print)978-1-6654-4777-5
Publication statusPublished - 2021
Event2021 IEEE International Ultrasonics Symposium (IUS) - Virtual at Xi'an, China
Duration: 11 Sep 202116 Sep 2021


Conference2021 IEEE International Ultrasonics Symposium (IUS)
Abbreviated titleIUS 2021
CityVirtual at Xi'an

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


  • capacitive micromachined ultrasound transducers
  • pre-charged CMUT
  • zero-bias transducers
  • ultrasound power transfer
  • accelerated lifetime test


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