NIR-responsive structural color hydrogel microchannel for self-regulating microfluidic system

Abstract

Intelligent microfluidic devices with the capacities to flexibly adjusting the flow rate and flow direction have attracted increasing interest in recent years. Here, we present a responsive structural color hydrogel microchannel with the advanced functions of controllable fluid manipulating and visualized state-feedback by employing photothermal responsive graphene-doped N-isopropylacrylamide (NIPAM) hydrogel to negatively replicate the tubular colloidal crystal array templates. Because of the characteristics of graphene and NIPAM hydrogel, the obtained hydrogel microchannel exhibited a light-controlled reversible shrinking behavior and a corresponding structural color shift. It was demonstrated that when this intelligent microchannel was integrated into microfluidics, it presented a dynamically adjustable inner diameter and provided an intuitive visual state-feedback. In addition, the asymmetric irradiation of near-infrared (NIR) laser could induce a bending behavior of the hydrogel microchannel, enabling a visualized sample flow-switching process. These features indicated that the customized responsive microchannels possessed great potentials in constructing self-regulating micropumps and supporting oriented sensing analysis .