Low‐Temperature Bending Fatigue of MXene/PDMS Flexible Pressure Sensor

Abstract

cycles under 6.67 kPa pressure. [10] It is clearly seen that MXene-based pressure sensor exhibits a high mechanical fatigue stability under cyclic loading.As flexible sensors often need to withstand complex deformation, great efforts also focus on the bending durability of MXene-based flexible sensors. For the 3D MXene-based volatile organic compounds sensor reported by Yuan et al., the sensing responses present little decreased under 1000 bending cycles. [11] Li et al. fabricated a MXene/Ag-based sensor, which showed good endurance after 2000 bending cycles owing to the electrostatic cross-linking between MXene and matrix. [12] Song et al. indicated the resistance of hollowstructured MXene-PDMS sensor displayed a small attenuation after 1000 bending cycles. [13] This phenomenon is attributed to the slippage between adjacent MXene layers leading to the reduction of conductive paths. Clearly, MXene-based flexible sensors bear fewer cycles during bending test compared with that being compressed. By using finite element analysis, Sakai et al. found a strain concentration in the parylene layer around the contact electrode edge. That is the result of inhomogeneous bending due to the difference in stiffness between the contact electrode and the organic layer. [14] Most previous studies are focused on the structure design and modifying MXene to improve the sensor performance; however, the bending fatigue mechanism of MXene-based sensor needs to be further explored.With the developing of Internet of Things, flexible pressure sensors are required to work under extreme environment such as low temperatures. [15,16] Owing to the low glass transition temperature (<−100 °C), [17] PDMS can be safely applied in flexible sensors working at low temperature conditions, acting as a flexible substrate or matrix. To date, several groups have conducted studies on mechanical properties for flexible sensor based on MXene/PDMS composite. Chen et al. observed that the resistance of MXene/PDMS film for pressure-sensing applications showed negligible change after 1000 working cycles at room temperature. [18] For flexible-wrinkled MXene/PDMS sensor reported by Cai et al., the output-voltages exhibited no obvious degradation after 10 000 loading/unloading cycles at room temperature. [19] These works focused on the fatigue endurance of MXene/PDMS-based sensor at room temperature. With decreasing temperature, the elastic modulus of PDMS will decreases linearly, [20,21] which will enlarge the stiffness mismatch between PDMS and MXene. [22] In addition, MXeneThe flexible and wearable Ti 3 C 2 (MXene)-based sensors are attracting wide attention in various applications owing to high sensitivity and flexibility. However, as a key characteristic, the bending endurance of such sensors under low temperature is yet to be explored. Herein, the flexible MXene/polydimethylsiloxane (PDMS) pressure sensor is fabricated by dip coating, which exhibits good mechanical stability over 10 000 bending cycles above 10 °C. When the temperature decreases to −40 °C, a t...

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