Electrical Interconnects Fabricated From Biodegradable Conductive Polymer Composites

This paper presents the development and characterization of biodegradable electrical interconnects for transient implantable medical devices. The interconnects comprised micropatterned biodegradable conductive polymer composites, which were developed using iron (Fe) microparticles as the conductive filler and polycaprolactone (PCL) as the insulating matrix. The electrical properties of the composites were investigated under various degradation conditions. Electrical percolation was observed at 17% Fe volume fraction, but higher volume fractions exhibited more stable electrical resistivity throughout the time course of physiological degradation. The electrical resistivity of 40%vf Fe-PCL composites increased tenfold in an emulated packaged environment under degradation. Biodegradable electrical interconnects based on 40%vf Fe-PCL composites were successfully micropatterned in daisy-chain structures, illustrating the process compatibility of Fe-PCL composites for interconnect applications. The electrical resistance of the packaged daisy-chain structures exhibited a reasonable increase under degradation. An electrical lifetime of over five days was also achieved. System integration with a commercial humidity sensor and analytical calculations supporting other application scenarios confirmed the feasibility of micropatterned Fe-PCL interconnects for use in implantable electrical systems.