An ultrasensitive flexible pressure, temperature, and humidity sensor based on structurally adjustable nano-through-hole array films

Abstract

In recent years, flexible sensors have been reported in numerous applications; however, they still face challenges such as single response to stimulus signals and low sensitivity. We report a flexible sensor based on structurally adjustable nano-through-hole array films that have high responses to pressure, temperature, and humidity. Polypyrrole/polyurethane single-walled carbon nanotube films with different sizes of nano-through-hole array films are prepared using anodic aluminum oxide templates, and the relationship between their pore diameter and pore depth and the three sensing properties is discussed in depth using finite element simulation and other methods. The experimental results show that the nano-through-hole array film with a pore diameter of 440 nm and a pore depth of 6.9 μm has a higher specific surface area and stress–strain response speed. The pressure sensitivity of the sensor reaches up to 102.99 kPa⁻¹ within 0.004–10 kPa; the temperature sensitivity reaches up to 0.72% °C⁻¹ within 20–80 °C; the humidity sensitivity reaches up to 3.51% RH⁻¹ within 20–80% RH; and the crosstalk between the three response signals is less than 5%. The sensor shows great potential in the application of human physiological signal monitoring.