Origami Paper-Based Stretchable Humidity Sensor for Textile-Attachable Wearable Electronics.

Flexible and stretchable humidity sensors for wearable purposes have become increasingly important in health care and physiological signal monitoring. However, to the authors' knowledge, there is no report on flexible and stretchable paper-based humidity sensors that are low-cost, easily fabricated, and environmentally friendly. In this work, for the first time, we propose a stretchable, textile-compatible paper-based origami humidity sensor (POHS). The POHS can achieve good stretchability by integrating origami folding structures with a paper substrate, in which an airlaid paper acts as both a sensing material and a sensor substrate. This sensor has high sensitivity, good response, and recovery properties with excellent stability during deformation. This sensor has proved to be capable of dynamically monitoring the breathing rate after 300 folding and unfolding cycles. The flexible and stretchable nature of our POHS ensures that it is compatible for textile attachment and its utility for wearable applications, including respiration rate monitoring and diaper wetting detection. The facile fabrication process and convenient disposal method of the POHS proposed in this study provide feasible solutions for the development of low-cost wearable humidity sensors.