Tea nanoparticles modified halloysite clay coated polyurethane sponge as multifunctional sensors

Tea, as one of the three major beverages in the world, has antioxidant, anti-cancer, inhibitory inflammation, immune regulation, diabetes prevention, antibacterial and other effects. In this study, black tea and FeCl₃·6H₂O were chelated to functionally modify the outer surface of halloysite clay nanotube (Hal). A new nanomaterial with excellent photothermal properties, tea nanoparticles@Hal, was successfully synthesized. Tea nanoparticles@Hal powder can raise to 225.8 °C in 25 s, and the corresponding solution can raise to 50.5 °C in 8 min with a photothermal efficiency of 77.3 %. The tea nanoparticles@Hal was assembled on the polyurethane (PU) sponges by simply soaking to prepare conductive sensor. The flexible sensor shows a fast response time (132.8 ms) and a long service time (400 cycles), which have wide range of applications. The resistance changes with the pressure is in a regular functional relationship, and the sensor can measure the weight of objects with high accuracy. In addition, the sensor can stably monitor various physiological activities of the human body. When finger is bent, the sensor can produce the difference output signals. The prepared tea nanoparticles@Hal/PU sensor has broad prospects in fields such as human-computer interaction and medical detection.