Integrating Ti₃C₂T _x MXene Nanosheets with Thermoplastic Polyurethane Nanofibers as Wearable Humidity Sensors for Noninvasive Sleep Monitoring and Noncontact Sensing

The development prospects of wearable humidity sensorsin noninvasivediagnostic and noncontact sensing have attracted more and more attention.However, most of the existing humidity sensors are uncomfortable towear and require complex and high-cost fabrication methods, limitingtheir application in continuous and real-time detection. Herein, anall-nanofiber wearable humidity sensor, integrating Ti3C2T x MXene nanosheets withthermoplastic polyurethane (TPU) nanofibers, is proposed by combiningelectrospinning and vacuum magnetron sputtering with high sensitivity,fast response, and good anti-interference ability. Benefiting fromthe 2D/3D multilevel structure and Grotthuss chain reaction, the sensorexhibits an ultrahigh linear sensitivity of -91%, fast response/recoverytime (<3.7 s), and wide sensing range (11-95% RH). Moreover,the sensor is featured with portability, flexibility, breathability,and biocompatibility and is impervious to pressure, temperature, andsweat, contributing to real-time noninvasive monitoring of human respirationand skin moisture. In addition, it can respond remarkably and repeatablyto weak humidity changes, which facilitates the noncontact humiditysensing. Most importantly, a simple humidity detection device is assembledand applied to early warn about sleep-related diseases and constructa human-machine interaction interface (such as an intelligentburglar alarm) as a proof of concept.