Feasibility of Parylene C for encapsulating piezoelectric actuators in active medical implants

Alina Kohler; Felix Blendinger; Sonja Müller; Ulrich Mescheder; Volker Bucher

doi:10.3389/fmedt.2023.1211423

Feasibility of Parylene C for encapsulating piezoelectric actuators in active medical implants

Front Med Technol. 2023 Nov 17:5:1211423. doi: 10.3389/fmedt.2023.1211423. eCollection 2023.

Authors

Alina Kohler^#^{1

2

3}, Felix Blendinger^#¹, Sonja Müller^{1

4}, Ulrich Mescheder¹, Volker Bucher¹

Affiliations

¹ Faculty Mechanical and Medical Engineering (MME), Institute for Microsystems Technology (iMST), Furtwangen University, Furtwangen, Germany.
² Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg, Germany.
³ BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany.
⁴ Department of Microsystems Engineering IMTEK, University of Freiburg, Freiburg, Germany.

^# Contributed equally.

Abstract

Parylene C is well-known as an encapsulation material for medical implants. Within the approach of miniaturization and automatization of a bone distractor, piezoelectric actuators were encapsulated with Parylene C. The stretchability of the polymer was investigated with respect to the encapsulation functionality of piezoelectric chips. We determined a linear yield strain of 1% of approximately 12-µm-thick Parylene C foil. Parylene C encapsulation withstands the mechanical stress of a minimum of 5×10⁵ duty cycles by continuous actuation. The experiments demonstrate that elongation of the encapsulation on piezoelectric actuators and thus the elongation of Parylene C up to 0.8 mm are feasible.

Keywords: Parylene C; active implant; encapsulation; piezoelectric actuator; polymer; stretchability.