Materials Considerations Enabling Chronic Validation of a Wirelessly-Powered, Implantable Drug Delivery System

Chronically implanted drug delivery devices face significant challenges that affect tolerance and effective dosage upon implantation in living organisms. Foreign body reaction, for instance, is a well-known adverse response to implants and various materials strategies have been proposed to circumvent it, including surface coatings, topography, and morphology, but often they are limited to non-functional implants. Herein, we present a wireless and battery-free, fully-implantable drug delivery system capable of on-demand drug release enabled by rational materials selection. The system relies on electrolytic pumps for drug delivery, which necessitate optimization of surface degradation mechanisms to allow for long-term stability <i>in-vivo</i>. Materials choice, design, and fabrication techniques will be discussed, as they pertain to facilitating the chronic implantation and tolerance of devices. Carefully engineered devices have demonstrated excellent biocompatibility in studies as long as 4 months post-implantation, and successful drug delivery to the bloodstream from the subcutaneous implant after many weeks implanted.