Advanced radio frequency materials for packaging of implantable biomedical devices
Most electronic biomedical implants are packaged with an epoxy coating that reduces the lifetime of the implant, or a metal casing that complicates wireless telemetry in a biological system. Advanced radio frequency (RF) materials commonly used in cell phones and high frequency devices have the ability to enhance implanted devices. Therefore this document analyzes the functionality and biocompatibility of implantable materials. For functionality, packages are tested for RF efficiencies in telemetry and powering, while biocompatibility is tested using the chronic rabbit animal model. Low-temperature Co-fired Ceramic (LTCC) and Liquid Crystal Polymer (LCP) are tested for functionality as packaging materials. LTCC, Anisotropic Conductive Adhesive (ACA), parylene, LCP, and silicon are tested against alumina, a common biocompatible ceramic for tissue response. The tissue response in the form of inflammation and encapsulation is observed and quantified in order to justify a package material that is used in the final design of the implanted device.^ Functionality tests prove that both LTCC and LCP are optimal materials for packaging with each having its own advantages in package design. Biocompatibility results indicated all materials tested allow for integration into a biologically implantable device, with LCP showing the most promise due to its lack of fibrous encapsulation throughout the 4 week study.^
Pedro P. Irazoqui, Purdue University.