Humidity sensors based on flexible sensitive nanomaterials are very attractive in noncontact healthcare monitoring. However, the existing humidity sensors have some shortcomings such as limited sensitivity, narrow relative humidity (RH) range, and a complex process. Herein, we show that a tin sulphide (SnS) nanoflakes-based sensor presents high humidity sensing behaviour both in rigid and flexible substrate. The sensing mechanism based on the Schottky nature of a SnS-metal contact endows the as-fabricated sensor with a high response of 2491000% towards a wide RH range from 3% RH to 99% RH. The response and recovery time of the sensor are 6 s and 4 s, respectively. Besides, the flexible SnS nanoflakes-based humidity sensor with a polyimide substrate can be well attached to the skin and exhibits stable humidity sensing performance in the natural flat state and under bending loading. Moreover, the first-principles analysis is performed to prove the high specificity of SnS to the moisture (H₂O) in the air. Benefiting from its promising advantages, we explore some application of the SnS nanoflakes-based sensors in detection of breathing patterns and non-contact finger tips sensing behaviour. The sensor can monitor the respiration pattern of a human being accurately, and recognize the movement of the fingertip speedily. This novel humidity sensor shows great promising application in physiological and physical monitoring, portable diagnosis system, and noncontact interface localization.

The electronic and mechanical properties of monolayer SnP₂ are calculated by density functional theory (DFT), showing that monolayer SnP₂ is a quasi-direct semiconductor with a moderate bandgap of 1.44 eV. The phonon dispersion, the molecular dynamics and the strain energy reveal that SnP₂ is dynamically, thermally and mechanically stable. Further, the bandgap of SnP₂ sheet can be effectively adjusted by applying strain. These results open the door for future applications in catalysis and optoelectronics.

As the next-generation solder, nano-copper paste has attracted wide attention in the field of power electronics due to its outstanding properties. In this paper, the effect of pressure on nano-copper sintering is investigated. It is found that the electrode of chip cannot be contacted to the nano-copper layer when no pressure is applied, whereas during the sintering there are fewer defects on the surface of nano-copper compared with that of pre-sintering under certain pressure conditions. Besides, the results of metallographic microscope confirm that the sintering quality of nano-copper has a positive relationship with pressure.