Performance improvement of micro-ultrasonic motors using the thickness shear mode piezoelectric elements

Tomoaki Mashimo, Yoshinari Oba

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


We propose a one-millimeter-scale traveling-wave ultrasonic motor that uses a thickness shear mode (15-mode) piezoelectric elements with a high shear piezoelectric coefficient. This thickness shear mode makes the micromotor suitable for operating with higher energy efficiency than conventional micromotors and enables a low voltage operation and a high torque generation. In this study, we build a thickness shear mode-driven micro-ultrasonic motor and demonstrate the improvement in motor performance. A micromotor comprising a cube with a side length of 1 mm and four piezoelectric plates is fabricated, and its dynamic and static characteristics are evaluated experimentally. With an optimal preload mechanism, the micromotor obtains unprecedented performance measures: an efficiency of 2.1% and a torque of 40 µNm, which are 3–4 times larger than those of a comparable micromotor using typical expansion mode (31-mode) piezoelectric elements. Currently, the proposed motor is the most powerful micromotor in 1–2 millimeter-scale actuators and represents a new benchmark for micromotors.

Original languageEnglish
Article number113347
JournalSensors and Actuators A: Physical
Publication statusPublished - Mar 1 2022
Externally publishedYes


  • Microactuators
  • Micromotors
  • Piezoelectric actuators
  • Thickness shear mode
  • Ultrasonic motors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering


Dive into the research topics of 'Performance improvement of micro-ultrasonic motors using the thickness shear mode piezoelectric elements'. Together they form a unique fingerprint.

Cite this