Facile primary battery-based humidity sensor for multifunctional application

Power generation humidity sensor has attracted attention in recent years due to its great potential in self-powered electronics. Herein, combining with the working mechanisms of primary battery and humidity sensor, we propose a facile primary battery-based device (PBD) with dual functions of humidity sensing and power generation, which is fabricated by copper adhesive tape (as positive electrode), lithium chloride (LiCl) active layer (for adsorption and conduction), and aluminum adhesive tape (as negative electrode) on the ceramic substrate. By regulating the concentration of the LiCl, 1.0 mol/L LiCl-based PBD can be developed as a humidity sensor, which exhibits a sensitivity of 4.86 mV/RH and good linearity in a wide detection range (10.9%−91.5% relative humidity) at room temperature (25 °C). Moreover, 2.0 mol/L LiCl-based PBD can be developed as a power generator due to its high output of 0.55 V. Finally, multifunctional applications (such as respiratory monitoring, non-contact switch, lighting light-emitting diode (LED)) of the PBDs are demonstrated. This work not only provides a facile avenue to develop dual-function devices, but also exhibits a great potential in self-powered humidity sensors.