Conformal Hydrogel-Skin Coating on a Microfluidic Channel through Microstamping Transfer of the Masking Layer

Abstract

Poly-(dimethylsiloxane) (PDMS) is used in microfluidicsowing toits biocompatibility and simple fabrication. However, its intrinsichydrophobicity and biofouling inhibit its microfluidic applications.Conformal hydrogel-skin coating for PDMS microchannels, involvingthe microstamping transfer of the masking layer, is reported herein.A selective uniform hydrogel layer with a thickness of similar to 1 mu mwas coated in diverse PDMS microchannels with a resolution of similar to 3 mu m, maintaining its structure and hydrophilicity after 180 days(6 months). The wettability transition of PDMS was demonstrated throughthe switched emulsification in a flow-focusing device (water-in-oil[pristine PDMS] to oil-in-water [hydrophilic PDMS]). A one-step bead-basedimmunoassay was performed to detect the anti-severe acute respiratorysyndrome coronavirus 2 IgG using a hydrogel-skin-coated point-of-careplatform.