Microfluidic integration of high power dual-beam laser traps for cell mechanical measurements

The combination of microfluidic systems with laser optical manipulation of suspended objects extends the range of possible investigations in lab-on-chip environments. As an example, mechanical properties of cells can be measured with a specific dual-beam laser trap called the optical stretcher on a single cell basis. The combination of high power laser beams in excess of 1W into a microfluidic environment with high spatial accuracy presents considerable challenges. Here we discuss three alternatives to achieve this goal: a simple glass-capillary setup with only one flow channel, a more elaborate optofluidic chip made of Polydimethylsiloxane (PDMS) for rapid prototyping, and a monolithic glass chip for high durability, damage threshold and optical clarity. Advantages and disadvantage are being discussed. Such microfluidic optical stretcher setups open new possibilities for label-free characterization of cells with biotechnological applications.