LAUSR

Poly(dimethylsiloxane) (PDMS) is used in microfluidics owing to its biocompatibility and simple fabrication. However, its intrinsic hydrophobicity and biofouling inhibit its microfluidic applications. Conformal hydrogel-skin coating for PDMS microchannels, involving the microstamping transfer of the masking layer, is reported herein. A selective uniform hydrogel layer with a thickness of ∼1 μm was coated in diverse PDMS microchannels with a resolution of ∼3 μm, maintaining its structure and hydrophilicity after 180 days (6 months). The wettability transition of PDMS was demonstrated through the switched emulsification in a flow-focusing device (water-in-oil [pristine PDMS] to oil-in-water [hydrophilic PDMS]). A one-step bead-based immunoassay was performed to detect the anti-severe acute respiratory syndrome coronavirus 2 IgG using a hydrogel-skin-coated point-of-care platform.