Open Collections

Abstract

As drugs with modular timing are lacking, devices allowing the control of the dose amount and timing expand the possibilities for future research in related areas, such as setting dose amounts to satisfy various patient conditions. Herein, three different devices are devised by looking at microelectromechanical systems (MEMS) drug delivery devices from various perspectives. All of the devices offer thermally stimulated modular drug delivery control. Each device implements environmentally conscientious fabrication and experimental techniques to inspire similar research. As biomedical applications are evident for all three devices, many material choices and fabrication techniques are determined based on their impact on biocompatibility. For the first device, an electromagnetic energy source in the radio frequency (RF) range delivers power to a stent circuit via resonant inductive coupling, allowing a thermally triggered gel release via Joule heating. A gold-electroplated, medical-grade stainless steel stent, serving as the base of the prototype device, melts a coating made from an emulsion composed mainly of dodecanoic acid. The average melting temperature of two different emulsions was 40.8±0.7 °C, a suitable value for the targeted application. For the second device, pulsed thermal energy causes piecewise actuation of a nitinol cantilever, providing the mechanical force required to evacuate a chamber constructed of parylene C. The chamber and normally closed channels that serve as valves are all of parylene C construction, leading to the flexibility of the device. The nitinol cantilever is an actuator capable of yielding successive partial chamber evacuations advancing toward complete evacuation. Theoretically predicting a release amount uses calculations for the expected recovery of the actuator based on displacement characterization via a logistic curve fit against actuator temperature data. The measured release amounts correlate well with the theoretically predicted values. For the third device, a remote control stent device for localized treatments performs a simulated drug release. The transmission of resonant RF signals facilitates remotely controllable temperature increases from the stent device. The nitinol actuator affixed to the stent is capable of precise piecewise actuation. Due to the actuator capabilities and the normally closed channels of the micropump, multiple releases are possible from the device.