Direct laser writing photonic crystal hydrogel sensors for in-situ sensing in microfluidic device

Photonic crystal hydrogels (PCHs) are promising materials for in-situ sensing demands in cell incubation systems such as microfluidic devices. However, the lack of ability to precisely construct and settle PCH sensors limits their future development. In this paper, we developed a versatile and highly controllable strategy to fabricate PCH sensing systems via direct laser writing (DLW) technology. We show that, PCH microsensors with precise geometries and diverse compositions could be exactly generated at desired positions using two-photon lithography (TPL). With such smart sensors, in-situ and spatiotemporal monitor of environmental parameters in liquid microdomains could easily be achieved using a microscope. This is demonstrated by generating PCH sensors for in-situ pH and metal ion strength analysis in microfluidic devices.