Multi-Degree-of-Freedom Thin-Film PZT-Actuated Microrobotic Leg

• Published in: Journal of microelectromechanical systems Vol. 21; no. 6; pp. 1492 - 1503
• Main Authors: Rhee, C., Pulskamp, J. S., Polcawich, R. G., Oldham, K. R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-12-2012; Institute of Electrical and Electronics Engineers
• Subjects: Actuators; Applied sciences; Computer science; control theory; systems; Control theory. Systems; Exact sciences and technology; Fabrication; lead zirconate titanate (PZT); Legged locomotion; Mechanical engineering. Machine design; Piezoelectric devices; Precision engineering, watch making; Robotics; Robots; Silicon; Encapsulation; Legged locomotion; Energy consumption; Actuators; PZT; Micromachine; Aspect ratio; Piezoelectric ceramics; Robotics; Thin film; Added mass; Displacement measurement; Piezoelectric actuators; lead zirconate titanate (PZT); piezo-electric devices; robots; Production process
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2012.2211573

As a novel approach to future microrobotic locomotion, a multi-degree-of-freedom (m-DoF) microrobotic appendage is presented that generates large range of motion (5 ° -40 ° ) in multiple axes using thin-film lead zirconate titanate (PZT) actuators. Due to the high driving force of PZT thin films and a robust fabrication process, m-DoF legs that retain acceptable payload capacity ( ~ 2 mg per leg) are achieved. The fabrication process permits thin-film PZT actuator integration with more complex higher aspect ratio silicon structures than previous related processes, using vertical silicon dioxide barrier trenches formed before PZT deposition to provide robust encapsulation of the silicon during later XeF 2 release. Planarization of the barrier trenches avoids detrimental effects on piezoelectric performance from the substrate alteration. Once fabricated, kinematic modeling of compact PZT actuator arrays in prototype leg joints is compared to experimental displacement measurements, demonstrating that piezoelectric actuator and assembled robot leg joint performance can be accurately predicted given certain knowledge of PZT properties and residual stress. Resonant frequencies, associated weight bearing, and power consumption are also obtained.