MXene-based flexible pressure sensor with piezoresistive properties significantly enhanced by atomic layer infiltration

The flexible pressure sensor has been credited for leading performance including higher sensitivity, faster response/recovery, wider detection range and higher mechanical durability, thus driving the development of novel sensing materials enabled by new processing technologies. Using atomic layer infiltration, Pt nanocrystals with dimensions on the order of a few nanometers can be infiltrated into the compressible lamellar structure of Ti3C2Tx MXene, allowing a modulation of its interlayer spacing, electrical conductivity and piezoresistive prop-erty. The flexible piezoresistive sensor is further developed from the Pt-infiltrated MXene on a paper substrate. It is demonstrated that Pt infiltration leads to a significant enhancement of the pressure-sensing performance of the sensor, including increase of sensitivity from 0.08 kPa-1 to 0.5 kPa-1, extension of detection limit from 5 kPa to 9 kPa, decrease of response time from 200 ms to 20 ms, and reduction of recovery time from 230 ms to 50 ms. The mechanical durability of the flexible sensor is also improved, with the piezoresistive performance stable over 1000 cycles of flexure fatigue. The atomic layer infiltration process offers new possibilities for the structure modification of MXene for advanced sensor applications.