Micromilling of molds for microfluidic blood diagnostic devices

INTRODUCTION In the application to diagnostic devices for blood flow, microfluidic devices with high aspect ratios (such as features with lateral and out-of-plane dimensions on the order of 250-1000 μm) are particularly useful as they enable the testing of a spectrum of flow conditions (e.g., shear rates) while operating at the limiting dimensions for physiological relevance in blood rheology experiments. However, such features are difficult and time consuming to fabricate with conventional semiconductor processes such as lithography, deposition, or etching. Further, structures with multiple out-of-plane dimensions are tedious, expensive, or impossible to fabricate with these semiconductor processes. Alternative micromanufacture methods which are capable of producing high aspect ratios, such as micro-edm and micro-ecm, require the manufacture of initial prototypes to serve as customized electrodes [1].