Giant humidity responsiveness of WSe₂ nanosheets for novel electronic listening and touchless positioning interface

Since few years, sensing electronics based on metal oxide, carbon based materials, inorganic–organic hybrid materials have intensively exploited for biomedical applications. The performance of sensors most likely to be relies on high surface to volume ratio of primary sensing elements for better interactions. Monitoring dynamic response demands highly sensitive fast response sensors. Here we report for the first time, high performance sensors based on WSe₂ nanosheets having extrinsic semiconducting behaviour as active resistive sensing material. The WSe₂ nanosheets are synthesized by high yield sonochemical exfoliation technique and are characterized by TEM, absorption spectroscopy and Raman spectroscopy. Subsequently, WSe₂ resistive sensor was fabricated and fast humidity sensing is demonstrated. The sensor was exploited for electronic listening towards human breathing, whistling and speaking. The novel touchless motion sensing applications are also demonstrated. The sensor shows excellent performance with better sensitivity and reproducibility due to optimized material properties and device configuration. Over all, the results advocate development of resistive sensors for biomedical as well as for intelligent touchless sensing applications.