A micromachined piezoelectric ultrasonic transducer operating in d 33 mode using square interdigital electrodes

Chao Wang, Zheyao Wang, Tian Ling Ren, Yiping Zhu, Yi Yang, Xiaoming Wu, Haining Wang, Huajun Fang, Litian Liu

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


This paper presents the design, fabrication, and characterization of a piezoelectric micromachined ultrasonic transducer (pMUT) operating in d 33 mode. A piezoelectric PZT thin film is polarized along the in-plane direction using top square interdigital electrodes (IDEs), and the in-plane polarization and IDEs enable the pMUT to operate in d33 mode, which allows the PZT to convert the ultrasonic pressure-induced in-plane stresses into in-plane direction charges. The square IDEs fully exploit the stresses of the diaphragm to improve sensitivity and increase device capacitance, and the pMUT is optimized by varying the IDE dimensions rather than the thickness of the PZT film. Theoretical and finite-element analyses are performed to optimize the diaphragm and the IDE dimensions in terms of resonance frequency and sensitivity, respectively. The ultrasonic directivity of the pMUTs with different packaging configurations is characterized, showing large ultrasound inlet areas beneficial to ultrasonic applications requiring high directivity.

Original languageEnglish (US)
Pages (from-to)967-975
Number of pages9
JournalIEEE Sensors Journal
Issue number7
StatePublished - Jul 2007
Externally publishedYes


  • D mode
  • Directivity
  • In-plane polarization
  • Interdigital electrode (IDE)
  • PZT
  • Ultrasonic transducer

ASJC Scopus subject areas

  • Instrumentation
  • Electrical and Electronic Engineering

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