ABSTRACT Lab‐on‐a‐chip (LOC) devices allow for the manipulation of chemical synthesis and biological processes at small scales. Microfluidic devices are still limited in their flexibility; by employing two‐photon Direct Laser Writing (DLW) limitations in the fabrication of reconfigurable microfluidic devices can be overcome. In a post‐modification process of assembled microfluidic channels, a Christmas‐tree‐shaped microfluidic gradient generator (MGG) is equipped with dynamic trapping chambers based on thermoresponsive poly(N‐isopropylacrylamide) (pNIPAM) soft microactuators. In this study, we show an integrated microfluidic platform that combines dynamic pNIPAM microactuation with on‐chip functionalization, fluorescent labeling, and controlled release of amine‐functionalized polystyrene beads. The novelty of this work resides in the successful combination of all these functions on a single microfluidic device, which is highly relevant for the field of reconfigurable microfluidics. This dynamic approach enables us to trap beads at room temperature inside the equipped chambers and perform fluorescent labeling and washing steps on chip, before the beads are released at 45°C, without altering the flow conditions. The method offers great flexibility and a high degree of freedom in the fabrication of dynamic microfluidic devices, with excellent adaptability to experimental conditions and on‐demand labeling in real time.
Barwig et al. (Wed,) studied this question.