Toward Enhanced Humidity Stability of Triboelectric Mechanical Sensors via Atomic Layer Deposition

Humid conditions can disrupt the triboelectric signal generation and reduce the accuracy of triboelectric mechanical sensors. This study demonstrates a novel design approach using atomic layer deposition (ALD) to enhance the humidity resistance of triboelectric mechanical sensors. Titanium oxide (TiO_x) was deposited on polytetrafluoroethylene (PTFE) film as a moisture passivation layer. To determine the effective ALD process cycle, the TiO_x layer was deposited with 100 to 2000 process cycles. The triboelectric behavior and surface chemical bonding states were analyzed before and after moisture exposure. The ALD-TiO_x-deposited PTFE showed three times greater humidity stability than pristine PTFE film. Based on the characterization of TiO_x on PTFE film, the passivation mechanism was proposed, and it was related to the role of the oxygen-deficient sites in the TiO_x layer. This study could provide a novel way to design stable triboelectric mechanical sensors in highly humid environments.