Laser-assisted micromachining: An innovative tool for advancing the multifunctional optofluidic lab-on-a-chip

Abstract

Ultrafast laser micromachining is a technological innovation with exciting potential for many applications and has led to impressive advances in the study of light-matter interactions. In this context, the laser-assisted wet etching fabrication technique has opened new frontiers in the optofluidic lab-on-a-chip, i.e. complex and easy-to-use microsystems capable of integrating multiple physicochemical processes on a single platform to replicate specific chemical, biological and medical tests typically performed in a laboratory. These miniaturised multifunctional laboratories exploit the synergy between the high sensitivity of optics and the unique ability to manipulate small quantities of microfluidics to develop a new frontier of analytical devices. The chips can be manufactured in monolithic 3D versions with no geometric constraints and are fully embedded in the substrate (typically fused silica). In addition to the advantage of using an inert substrate (strategic for biological applications), the elimination of the sealing step and the high mechanical strength offer numerous advantages. To demonstrate the potential of this new sensing platform, we report on the benefits of integrating in-plane 3D micro-optics to increase the S/N in-chip spectroscopic analysis in two case studies: flow cytometer devices and innovative chips for real-time Raman analysis of bio-samples in flow, even non-transparent ones.