Piezoelectric ultrasonic micromotor with 1.5 mm diameter

A piezoelectric ultrasonic micrometer has been developed using a lead zirconate titanate (PZT) ceramic/metal composite tube stator that was 1.5 mm in diameter and 7 mm in length. The micrometer was operated in its first bending vibration mode (similar to70 kHz), producing speeds from hundreds to over 2000 rpm in both rotational directions. The maximum torque-output was 45 muN-m, which is far superior to previous PZT thin film-based micrometers. This micrometer showed good reliability and stability for more than 300 hours of continued operation.