Towards a versatile point-of-care system combining femtosecond laser generated microfluidic channels and direct laser written microneedle arrays

Microneedle-based microfluidic systems have a great potential to become well-accepted medical devices for simple, accurate, and painless drug delivery and lab-on-a-chip diagnostics. In this work, we report on a novel hybrid approach combining femtosecond direct laser written microneedles with femtosecond laser generated microfluidic channels providing an important step towards versatile medical point-of-care systems. Hollow microneedle arrays are fabricated by a laser system designed for two-photon polymerization applications. Compression tests of two different types of truncated cone-shaped microneedle arrays prepared from OrmoComp® give information about the microneedle mechanical strength, and the results are compared to skin insertion forces. Three-dimensional microchannels are directly created inside PMMA bulk material by an ultrashort pulse laser system with vertical channels having adjustable cross-sectional areas, which allow attaching of microneedles to the microfluidic system. A comprehensive parameter study varying pulse duration and repetition rate is performed on two-photon polymerization to identify an optimal laser power range for fabricating microneedles using the same pulse duration and repetition rate as for microchannels. This addresses the advantage of a single laser system process that overcomes complex fabrication methods. A proof of concept flow test with a rhodamine B dye solution in distilled water demonstrates that the combination of microneedles and microchannels qualifies for microfluidic injection and extraction applications.