Al-Ni Nanofilm Powered Miniature Linear Actuator for Medical Devices

Abstract

Amedical device is sought to improve drug delivery options available to healthcare providers and patients; our initial focus is to develop a piston that can provide the power necessary to do an injection from an ingestible device. While many methods to administer drugs currently exist, the administration method in many cases is largely driven by factors that supersede ease, convenience, or comfort for the patient [1]. Many patients are saddled by cumbersome drug regimens that expose them to the risk of complex and painful drug administration paths and dependence on medical sharps [2, 3]. For these patients, being able to take injectable drugs orally allows them to use what appears to them to be simple, traditional drug delivery methods in lieu of injections that are painful and inconvenient. In order to perform an injection with a device that fits within an ingestible form factor, a novel piston is required. A concept design for an Al-Ni nanofilm powered miniature linear actuator has been developed in order to perform jet injections from within the gastrointestinal anatomy of a patient. This actuator consists of a small pressure vessel filled with liquid alcohol that undergoes a phase change to gas and generates pressure that can be used to cycle a piston in a drug loaded cylinder. Via exothermic reaction, nanofilm deposits thermal energy into the alcohol filled pressure vessel in order to generate the pressure needed to perform a jet injection. Cylindrical pressure vessel chambers with a diameter of 7mm and heights ranging from 3mm to 7.5mm were 3D printed and used to measure peak internal pressure vessel pressure as well as work output. The piston was used to push incompressible fluid through a nozzle in order to characterize the actuator’s work output. By using Bernoulli’s Equation, pressure on the piston head as a function of piston location along the stroke length was determined to characterize actuator performance as a function of pressure vessel size. The pressure vessel and the piston were modeled theoretically and empirically in order to identify the relevant design parameters so the piston can be effectively incorporated into the overall injection device.