Hydrophobic and multifunctional strain, pressure and temperature sensor based on TPU/SiO2-ILs ionogel for human motion monitoring, liquid drop monitoring, underwater applications

Ionogel-based flexible electronic devices have attracted extensive attention from industry and academia due to their unique advantages in wearable electronic devices, human motion sensing, etc. However, the internal ionic liquids (ILs) or polymers have weak resistance to liquid interference, which limits the development of ionogel in the actual environment. In this paper, TPU/SiO2-ILs (Thermoplastic polyurethane/SiO2-Ionic liquids) ionogel with micro-nano structures on the surface was constructed by sandpaper template method and further modified by 1 H, 1 H, 2 H, 2 H-perfluorooctyltrichlorosilane to enhance its hydrophobicity. The ionogel sensor has a high sensitivity, a fast strain response time (346 ms), and excellent mechanical properties. In addition, the sensor can still show a stable response signal after 1000 s of strain and compression cycle testing. The ionogel sensor’s excellent hydrophobic properties allow it to be used not only in wearable electronic devices to detect human physiological activity in dry or underwater environments and for writing recognition systems, but also to monitor tiny response signals caused by toy fish wiggling and droplet dripping. Most importantly, compared with other sensors that can only monitor a single stimulus, the TPU/SiO2-ILs ionogel sensor has a wide and multifunctional detection range for stimuli in different environmental such as strain (0.1–200%), pressure (0.6–25 kPa) and temperature (30–100 °C). Thus, the TPU/SiO2-ILs ionogel shows great potential for applications in areas such as smart electronic skin, human motion monitoring, underwater communication and underwater environmental monitoring.