A thermally actuated biocompatible flexible micropump for surface adaptable mounting

Abstract

Pulsed thermal energy causes piecewise actuation of a nitinol cantilever providing the mechanical force required to evacuate a chamber constructed of parylene C. This proof-of-principle micropump demonstrates an alternative to typical evacuation and rectification methods utilized in most micropumps. 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 functions as an actuator capable of yielding successive partial chamber evacuations until achieving complete evacuation. Piecewise shape recovery of the actuator was made viable by implementing a Peltier device, providing the means for supplying responsive and controlled thermal energy. Experiments delivered measurements of consecutive advancement of shape recovery using a laser displacement sensor while monitoring the temperature with fiber-optic sensors. The release of a saturated lithium chloride solution from the pump was monitored by observing conductivity changes in the experimental area. Theoretically predicting a release amount used 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 correlated well with the theoretically predicted values made using the temperature values obtained near the device during the release. These works provide novel approaches to micropump fabrication and implementation and new strategies for predicting the recovery of shape memory alloys. The micropump concepts are viable in many fields, such as biomedical applications: in vivo drug delivery, organ-on-chip, and lab-on-chip devices, to name a few. Likewise, a simple prediction for nitinol recovery has vast potential.