Continuous on-chip micropumping for microneedle enhanced drug delivery.

Microneedles are promising microfabricated devices for minimally invasive drug delivery applications. Needles can be integrated into a variety of devices. However, any portable drug delivery device with integrated microneedles will need an equally compact means to deliver therapeutics. This work presents microneedles integrated with an on-chip MEMS positive displacement micropump for continuous drug delivery applications. The generation and collapse of thermally generated bubbles with flow rectified by directional check valves are used to achieve net pumping through the device. Visualization methods have observed net flow rates of water out of a microneedle at approximately 2.0 nl/s with a pressure of 3.9 kPa. In addition, continuous pumping was achieved for more than 6 hours with the heaters actuating for over 18 hours (15,000 cycles) without failing.