Researchers at Penn State have developed a low-cost and easy-to-make, and highly reliable humidity sensor using hand-drawn interdigital electrodes from pencil-on-paper treated with NaCl solution. The resulting sensor is highly sensitive and can work over a wide range of relative humidity levels.
The applications of the sensor include monitoring respiratory rate, characterizing human skin types, evaluating skin barrier functions, and integrating with a diaper to create a smart diaper. The design and fabrication strategies used in this work could also be used to develop wearable, self-powered, and recyclable sensors and actuators in the future.
Ref: Guangyu Niu, Zihan Wang, Ye Xue, Jiayi Yan, Ankan Dutta, Xue Chen, Ya Wang, Chaosai Liu, Shuaijie Du, Langang Guo, Peng Zhou, Huanyu Cheng, and Li Yang; Pencil-on-Paper Humidity Sensor Treated with NaCl Solution for Health Monitoring and Skin Characterization; Nano Letters Article ASAPDOI: 10.1021/acs.nanolett.2c04384