Laser direct writing of Ga<sub>2</sub>O<sub>3</sub>/liquid metal-based flexible humidity sensors

Flexible and wearable humidity sensors play a vital role in daily point-of-care diagnosis noncontact human-machine interactions. However, achieving facile high-speed fabrication approach to realizing flexible remains challenge. In this work, capacitive-type Ga2O3/liquid metal-based sensor is demonstrated by one-step laser direct writing technique. Owing the photothermal effect of laser, Ga2O3-wrapped liquid metal particles can be selectively sintered converted from insulative conductive traces with resistivity 0.19 Ω·cm, while untreated regions serve as active sensing layers response moisture changes. Under 95% relative humidity, displays highly stable performance along rapid recover time. Utilizing these superior properties, able monitor human respiration rate, well skin palm under different physiological states for healthcare monitoring.