Selective Laser Etching technology for reconfigurable microfluidic and electrochemistry-on-chip

ABSTRACT Polydimethylsiloxane (PDMS) is widely used in academic microfluidics due to its favorable biocompatible properties and compatibility with soft lithography. Moreover, the recent developments of reconfigurable microfluidics rely on the microfabrication of sliding elements, which are 3D objects insertable inside a microfluidic chip to provide a given function. However, the complexity of microfluidic device geometries or sliding elements remains largely limited by the traditional microfabrication methods such as, among others, on SU-8 photolithography or dry epoxy films. Such methods are suited for simple, planar “2.5D” structures with uniform depths, yet struggle to produce more advanced architectures due to material and alignment constraints. To address these limitations, we propose to investigate advanced laser-based approaches, such as Direct Laser Writing (DLW) and Selective Laser Etching (SLE), which enable the construction of high-resolution, 3D designs. We further explore the use of SLE to fabricate sliding elements that enhance chip functionality, including chamber reconfiguration and biological sample manipulation. As a proof of concept, we show that these elements can be functionalized into pH microsensors, paving the way to reusable and reconfigurable electrochemistry-on-chip.