Wearable metal oxide semiconductor gas sensors synthesized in situ on hollow glass microfibers

• By utilizing hollow glass microfiber filled with liquid metal alloy as the substrate, the developed sensor achieves advantages such as flexibility, wearability, and low heat loss. • By matching the precise film thickness to the Debye length and optimizing the oxygen vacancy concentration through post annealing, the sensor performance was significantly enhanced. • The sensor stability in practical applications has been enhanced by an AF2400-ePTFE composite protective layer. The applicability of conventional metal oxide semiconductor (MOS) gas sensors in wearable devices is limited by their rigid substrates and extra heat loss. In this study, we developed a wearable MOS gas sensor using flexible hollow glass microfiber as the heating and synthesizing substrate. SnO 2 was deposited in situ on the hollow glass microfiber surface through atomic layer deposition. Subsequently, after post annealing and applying a breathable composite protective layer, the developed O 2 sensor was integrated into clothing to demonstrate its wearability. At an optimal operating temperature of 280°C, the sensor achieved responses of 35.4% and 33.2% to 10% O 2 before and after bending, while consuming only 285.1 mW of power.