Characterization of PDMS as Encapsulation for Implantable MEMS Systems

Modifications to a novel multi-layered polydimethylsiloxane (PDMS) encapsulation process that include improvements to the substrate cleaning procedure and roller casting application method were developed to produce a robust non-hermetic micropackage technology for chronic micro implant systems. Packaged interdigitated electrodes subjected to accelerated lifetime tests at 85 degree C in a saline environment had an average lifetime of 156.6 days, which exceeded the previous average lifetime by 22.3 days and suggests a packaging lifetime in the human body greater than 2 years and perhaps as long as 5 years. In order to understand the unexpectedly long lifetime, material characterization experiments were performed on PDMS films deposited by dip, spin and roller-casting. The results show that roller casting increases the mass density, decreases the vapor permeability, and increases bonding strength on FR4 PCB substrates by +2%, - 14%, +19%, respectively relative to the other deposition methods.

Autorentext

Di Sun received the B.S. degree in electrical engineering and automation systems from Xi'an Jiaotong University, Xi'an, China in 2011 and M.S degree in electrical engineering and computer science department from Case Western Reserve University, Cleveland, OH in non-hermetic packaging for implantable MEMS systems.