A Sustainable and Flexible Carbon Paper-Based Multifunctional Human-Machine Interface (HMI) Sensor.

We have executed a cost-effective approach to produce a high-performance multifunctional human-machine interface (HMI) humidity sensor. The designed sensors were ecofriendly, flexible, and highly sensitive to variability in relative humidity (%RH) in the surroundings. In this study, we have introduced a humidity sensor by using carbon paper (as both a substrate and sensing material) and a silver (Ag) conductive ink pen.