Flexible Graphite-Based Humidity Sensor Using Green Technology

The low-cost graphite based pattern on cellulose paper was investigated in the present work. The graphite pattern used was fabricated by using normal inkjet printer on paper substrate that acted as working substrate as well as sensing material for humidity measurements. The quantitative electrical characterizations were measured by using different saturated salt-solutions producing relative humidity (RH) of 15%–92% at room conditions of 27 °C and 40%RH. The developed humidity sensor shows the sensitivity of 0.57 MΩ/%RH in the whole range of 15%–92%RH with a linearity co-efficient of R2 = 0.968, response (τ res) and recovery (τ rec) time of 294 s and 306 s respectively. The hydrophilic nature of the paper substrate is helpful for sensing, though the fabricated sensor is not so viable in terms of sensitivity, repeatability, and reuse but the method was simple, low-cost, bio-degradable, and use & throw which can be used for flexible and green electronics.