Transfer‐Free Creation of Hierarchical Wrinkle Patterns for Stretchable and Compliant Strain and Contact Sensing

Abstract

Higher order hierarchical wrinkle patterns may extend the functionalities and enable new capabilities in the devices created, but current transfer‐based methods are often complex and tedious. This work develops a transfer‐free method to generate hierarchical wrinkle patterns in MXene thin films via controlled deflation of a latex balloon substrate by exploiting its thermal‐elastic properties. This work generates four different wrinkle patterns with varying strain sensitivity: 2D (GF = 0.593), 1D1D (GF = 0.0979), 2D1D (GF = 0.0165), and 2D2D (GF = 0.545). Taking advantage of the small strain response exhibited by the 2D1D electrode, this work fabricates stretchable stain‐insensitive contact sensors where its behavior can be tuned by varying the thickness of the spacer. When the spacer is 0.16 mm thick, the sensor is observed to have a pressure sensitivity of 0.0922, 0.109, and 0.112 kPa−1 at 0%, 25% and 50% stretching states respectively at pressures of <2500 Pa. When the spacer is 0.32 mm thick, the sensor is observed to have a pressure sensitivity of 0.154, 0.185, and 0.233 kPa−1 under 0%, 25% and 50% strain respectively between the pressure range of 2900–5200 Pa.