Non-Secondary Activating Flexible Liquid Metal Sensors with Excellent Waterproof Capability for Detection of Human Signals

In recent years, flexible sensors have gained increasing attention due to their excellent flexibility. Liquid metal (LM) has gradually become an ideal material for fabricating flexible sensors, thanks to its outstanding electrical conductivity and low-temperature fluidity. However, oxidation and the need for secondary activation of LM present significant technical challenges in the development of flexible LM sensors. In this paper, we introduce a simple method that integrates the flexibility of polydimethylsiloxane (PDMS) to fabricate flexible LM sensors with a sandwich structure. The sandwich-structured sensor demonstrates superior conductivity and effectively prevents LM oxidation and the need for secondary mechanical activation. Additionally, the PDMS-LM sensor exhibits excellent performance under various conditions, with a fast response time to mechanical stimuli (0.5 s), as well as outstanding durability and stability (>10,000 s of cycling). These remarkable properties give the sandwich PDMS-LM sensor great potential for the field of human motion monitoring, bringing further development and direction for intelligent sensing technology.