PEDOT:PSS/Natural Rubber Latex Inks for Screen-Printing Multifunctional Wearable Strain–Humidity Sensors

Wearable strain–humidity sensors are increasingly recognized for their role in healthcare and detecting human motion signals. However, many strain–humidity sensors require complex manufacturing processes and have limited applicability. In this study, based on the good miscibility between natural rubber latex (NRL) and poly (3,4-ethylenedioxythiophene):poly (4-styrenesulfonate) (PEDOT:PSS), PEDOT:PSS/NRL composite conductors are transferred onto fabric substrate through screen printing and prepared high-performance strain–humidity sensor. The PEDOT:PSS/NRL blends strain–humidity sensor exhibited good stability and durability (500 cycles) at 10% strain, achieves a gauge factor (GF) of 123.8 with excellent linearity, making it operational in detecting various human motions, such as finger bending, elbow bending, wrist bending, and so on. In addition, the PEDOT:PSS and water molecules interaction results in a humidity response time as low as 0.72 s and recovery time as low as 0.85 s for the PEDOT:PSS/NRL composite strain–humidity sensor, and a wide relative humidity detection range (6–83%), allowing it to be utilized for precise detection of human breathing. Furthermore, it can monitor the use's joint movement, facial muscle movement, and respiratory rate, which show its potential application prospect in health monitoring.