A robust, electrochemically driven microwell drug delivery system for controlled vasopressin release

Micro-electro-mechanical-system (MEMS) based implantable drug delivery devices represent a promising approach to achieving more precise dosing, faster release and better localization of therapeutic compounds than is possible with existing technology. Despite recent advancements, there remain challenges in being able to build systems that enable active control over the dose rate and release time, in a robust, low power but simple to fabricate package. Here we demonstrate an implantable microreservoir device that enables delivery of dose volumes as high as 15 mu l using an electrochemically based transport mechanism. This approach allows for a significant reduction in the amount of time required for drug delivery as well as reducing the dependence on the external physiological conditions. We present the overall design, operating principle and construction of the device, and experimental results showing the volume transport rate as a function of the strength of the applied electric field. The concentration profile vs. time, the power consumption, and ejection efficiency are also investigated. To demonstrate the medical utility of the device we also characterize the in-vitro release of vasopressin.