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research-article

A Study on Long-Term In Vitro Reliability of Intracochlear PZT Microactuators

[+] Author and Article Information
Yifeng Liu

Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98105
louisliu@uw.edu

Chuan Luo

Department of Precision Instruments, Tsinghua University, 30 Shuangqing Rd, Haidian, Beijing 100084, China
luochuan@gmail.com

Guozhong Cao

Department of Materials Science, University of Washington, 302 Roberts Hall, Seattle, WA 98195
gzcao@uw.edu

Clifford R. Hume

Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, VA Puget Sound, 1959 NE Pacific St, Department of Otolaryngology-Head and Neck Surgery Center at UWMC, Seattle WA 98195
hume@uw.edu

I. Y. (Steve) Shen

Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98105
ishen@uw.edu

1Corresponding author.

ASME doi:10.1115/1.4040103 History: Received March 11, 2018; Revised April 27, 2018

Abstract

An intracochlear lead-zirconite-titanite (PZT) microactuator integrated with a cochlear implant electrode array could be a feasible strategy to implement combined electric and acoustic stimulation inside the cochlea. The purpose of this paper is to characterize in vitro a prototype PZT microactuator for intracochlear applications, including service life, failure mechanisms, and lead leaching. PZT microactuators were driven sinusoidally to failure in air and in artificial perilymph. Frequency response functions and electrical impedance were monitored. After the PZT microactuators failed, the amount of leached lead was measured via inductive coupled plasma mass spectrometry. Two failure mechanisms are identified: electrical breakdown and structural failure. The electrical breakdown, possibly from loss of parylene encapsulation, is evidenced by a sudden and significant drop of the actuators’ electrical resistance. The structural failure, possibly from electrode delamination, is evidenced by a sudden and significant drop of frequency response functions. The amount of lead leached from the PZT microactuator is well below published safety guidelines from federal agencies.

Copyright (c) 2018 by ASME
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