Micropatterning Sub-100 nm MXene Arrays Using Surface Engineered Microchannel Templates

Abstract We demonstrate the fabrication of ultrathin, electrically continuous MXene micropattern arrays using a solution-phase, capillarity-driven microchannel templating approach. This strategy overcomes common integration barriers, including weak ink–substrate adhesion, inlet flake bridging, film delamination, and poor geometric confinement during micropattern formation. An open-ended PDMS microchannel template was conformally laminated onto a glass substrate, enabling pump-free wicking of aqueous MXene ink driven by capillary pressure at the liquid–air meniscus. Surface-engineered hydrophilic PDMS enhanced capillary wettability and stabilized meniscus propagation, while amine-functionalized glass substrates promoted strong interfacial adhesion through electrostatic interactions. Together, these modifications improved geometric confinement and film retention during solvent evaporation. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed successful etching and delamination of F-terminated MXene nanosheets, which are well-suited for confined-flow deposition. Optical microscopy-guided optimization identified 35 μm as the optimal channel width, effectively suppressing inlet blockage while improving flake redistribution and pattern fidelity. Atomic force microscopy (AFM) revealed stepwise thickness growth of approximately 10–15 nm per deposition cycle via sequential fill–dry processing, accompanied by a proportional increase in conductance. This approach enabled the formation of uniform, sub-100 nm-thick, interconnected MXene networks. The resulting MXene micropatterns were integrated into solution-gated field-effect transistor (FET) devices, exhibiting channel-length-linear, ohmic transport characteristics and n-type transfer behavior with a threshold voltage near 0.1 V and an on/off ratio of approximately 5. These FETs enabled the real-time detection of malathion at concentrations ranging from 1 to 20 ppm, producing distinct, stepwise ΔG/G responses.