Plasma surface modification and Parylene C Coating to reduce moisture penetration of implantable biosensor PEEK material packaging

Abstract

This study aimed to extend the lifespan of implantable biosensors by reducing moisture penetration in the packaging material PEEK, without any mechanical or physical modifications. The goal was to prevent moisture infiltration that can damage the sensor components inside the implantable packaging, thereby prolonging the sensor's lifespan. PEEK, the chosen packaging material, is a polymer known for its moisture permeability, where gas molecules (H2O or O2) can permeate through it, quantified as the Water Vapor Transmission Rate (WVTR). As an engineering plastic, PEEK is classified among polymers and offers the best WVTR performance. However, since implantable biosensors are ultra-small devices, a coating of the biocompatible material Parylene-C was applied to further enhance the WVTR performance of PEEK for long-term implantation. The coating was applied using a chemical deposition method with Parylene-C, aimed at reducing moisture penetration. Additionally, to improve the bonding strength between PEEK and Parylene-C, plasma treatment was used on the surface of PEEK specimens to enhance their surface characteristics. As a result, PEEK coated with Parylene-C demonstrated improved moisture permeability, confirming its potential to extend the lifespan of biosensors by preventing moisture infiltration.