Drug Delivery via Implantable Microchips

Abstract

Implantable microchip-based drug delivery systems represent a paradigm shift from conventional oral and injectable administration routes, enabling programmable, on-demand release of therapeutic agents from hermetically sealed reservoirs embedded within biocompatible substrates. Despite two decades of development since the first silicon-based microreservoir prototypes, clinical translation remains limited to a single commercially approved device, reflecting persistent challenges in reservoir capacity, power management, wireless communication reliability, and long-term biocompatibility. This study presents the Implantable Microchip Drug Delivery Evaluation Framework (IMDDEF), which systematically assesses five microchip architectures -- passive polymer-capped reservoirs, electrochemically activated metallic membranes, MEMS-actuated micropump arrays, wirelessly triggered thermally responsive systems, and closed-loop biosensor-integrated platforms -- across four drug delivery performance tasks: dosing precision, temporal release control, payload capacity utilisation, and in vivo biocompatibility duration. Our Microchip Drug Delivery Performance Index (MDDPI) integrates dosing accuracy, release timing fidelity, reservoir utilisation efficiency, tissue response severity, and device operational longevity. Closed-loop biosensor-integrated platforms achieved the highest MDDPI (0.918) through real-time glucose-responsive insulin release that maintained glycaemic targets in 91% of measurement intervals, while MEMS-actuated micropump arrays achieved the highest dosing precision (CV < 3.2%) across 500 programmed release events over a 180-day implantation period in a porcine subcutaneous model