Machine learning-enabled bimodal flexible tactile sensors for intelligent contact-noncontact recognition

PRPP integrates strain and humidity sensing functions on a single unified sensing platform. • Its distinctive porous structure endows PRPP with a broad strain range (0–80%) and low energy loss coefficient of 0.13. • PRPP shows excellent humidity-sensing performance and can serve for real-time human respiration monitoring. • The integration of humidity/pressure dual-mode PRPP sensor creates a broader platform for its application. Flexible pressure sensors with porous architectures have attracted extensive attention owing to their excellent stability and sensing performance, demonstrating great potential in applications such as electronic skin and healthcare monitoring. However, most existing sensors are often limited to single-modal signal transduction, and achieving synergistic multifunctionality within a unified signal platform remains a significant challenge. Humidity, as an essential environmental and physiological parameter, plays a vital role in enabling advanced interactive perception. Therefore, integrating high-performance humidity sensing with flexible pressure sensing has emerged as an important research direction. Herein, a polydimethylsiloxane (PDMS) composite foam (PRPP) modified with polypyrrole (PPy), reduced graphene oxide (rGO), and polydopamine (PDA) was fabricated through sequential in-situ polymerization combined with ultrasonication. The PRPP exhibits excellent mechanical resilience (1% plastic deformation after 500 compressions, 0.13 energy loss coefficient at 80% strain), rapid response/recovery time (80 ms/100 ms) and a low detection limit (0.1% strain). Benefiting from the in-situ growth of PPy, PRPP also shows remarkable humidity sensitivity, enabling real-time environmental monitoring. Furthermore, a dual-mode human-machine interface based on a PRPP array is developed for contact pressure sensing and non-contact humidity perception, providing a strategy for flexible sensors in intelligent interactive systems. A multifunctional flexible sensor is designed and fabricated. The flexible sensor simultaneously integrates strain sensing performance and humidity sensing performance within a unified platform via a rational functional integration strategy. The construction of multi-modal HMI interface realizes both contact and non-contact sensing. The integration of HMI interface and artificial intelligence algorithm provides excellent development prospects for the sensor in the fields of intelligent sensing, information transmission and human-computer interaction. Download: Download high-res image (139KB) Download: Download full-size image