A remotely powered electrolytic actuator with dose control for implantable drug delivery

“On demand” implantable drug delivery systems can provide optimized treatments, due to their ability to provide targeted, flexible and precise dose release. This dissertation focuses on remotely powering an implantable drug delivery system and providing a high degree of control over the released dose, addressing two important issues for “on demand” drug delivery: effective actuation stimulus and controllable dose release mechanism. This is accomplished by integration of a resonance-based wireless power transfer system, a constant voltage control circuit and an electrolytic pump. A novel actuation mechanism that is based on a cyclical actuation mode is introduced, implementing a solid drug in reservoir approach. The solid drug is partly dissolved during the initial stage, when a voltage is applied to the electrolytic pump, an electrolytic reaction occurs and the induced gas expansion drives the drug solution outwards. When the power turns off, the electrolysis bubble recombines and pressure decreases in the pump, which draws body fluids into the drug reservoir to dissolve more of the remaining solid drug. Power is repeatedly turned on and off to form a reproducible drug solution. A catalytic reformer enables the combination of the electrolytic pump and solid drug in reservoir approach as it significantly increases the electrolysis-bubble recombination rate, and is capable of fully replenishing the drug reservoir. Resonance-based wireless power transfer technology performs as the power source and a control circuit maintains a constant voltage for the actuator. Upon the application of an external alternating magnetic field, the electrolytic actuator is powered by a constant voltage regardless of movements of the device within an effective range of shift and rotation. This in turn contributes to a predictable dose release rate and greater flexibility in the positioning of external powering coils. Moreover, a thermo-responsive valve using “Poly N-Isopropylacrylamide” hydrogel is implemented in order to avoid the negative effect of drug diffusion. It allows actively controlled drug delivery and valving mechanism under the same input power signal. We have conducted proof-of-concept drug delivery studies using solvent blue 38 as the drug substitute, and the experimental results indicate the stability, feasibility and controllability of our system.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat