Towards a Laser-Integrated Module for Marker-Free Sorting of Micrometer-Sized Particles in Microfluidic Channels

In recent years, microfluidic devices have become important tools for cell analysis in biology and medicine. They enable fast and inexpensive analysis with reduced consumption of analytes. However, for optical detection involving FACS (fluorescence-activated cell sorting), sample preparation by attaching an antibody-labeled fluorochrome to the cell is required. Cell tagging by fluorochromes is a mature technology but might affect cell viability and function. In this article we present a novel concept for marker-free detection and first realization steps. We show the integration of a microfluidic chip and an electrically pumped GaAs-based oxide-confined VECSEL (vertical-extended-cavity surfaceemitting laser). Particles in the microchannel flow through the laser resonator and induce a change of the cavity resonance, thus allowing sensitive detection to trigger a subsequent sorting process.