Measurement and control of ultra-low liquid flowrates for drug delivery application

Abstract

Implantable, gas-driven drug pumps are safe, cost-effective and do not require internal batteries like their motor-driven counterparts. However, their flow rate cannot be changed after implantation. This work focuses on the development of an adjustable micro-flow regulator to be used in a programmable gas-driven pump. Several concepts of flow-restrictors made of microstructured silicone-elastomers have been evaluated and the manufacturing techniques have been optimized. Currently, fixed flowrates down to 250 nl/min can be achieved for a pressure drop of 3,4 × 105 Pa. Development of prototypes with adjustable flowrate is in progress. A test bench based on optical front-tracking for dynamic flowrate-analysis down to 10 nl/min has also been implemented. This enables an independent calibration of thermal micro-flow sensors as well as wide-range, low impedance flowrate measurements. © 2008 Springer-Verlag.