Fingerprint-Inspired Flexible Bimodal Tactile Sensor for Robotic Contact and Non-Contact Perception

Non-contact sensing is essential for the environmental adaptability and predictive capability of human-machine interaction. Although contact pressure sensing has made considerable progress, its perceptual capability is limited and cannot meet the demand for synergistic multi-information acquisition, while existing bimodal sensors commonly suffer from performance trade-offs and severe signal crosstalk during practical integration. Therefore, inspired by the tactile amplification mechanism of fingerprints and the hygroscopic swelling of the stratum corneum, we developed a flexible pressure-humidity bimodal (PHB) sensor for the fingertips of robots. The sensor achieves single-device integration of two sensing functions by utilizing a shared substrate, effectively overcomes signal crosstalk, and enables efficient decoupling and independent detection of pressure and humidity. The sensor exhibits a high pressure sensitivity of 5.44 kPa-1 and a wide detection range of 273 kPa, while the humidity sensing unit demonstrates a high humidity response of 159% and a fast response time of 0.85 s. Advanced fabrication techniques (3D printing, direct ink writing, and magnetron sputtering) ensure excellent batch consistency of the PHB sensor. Its practicality is validated by object recognition and multi-parameter vital sign detection in complex environments. This work provides a high-integration, anti-crosstalk multimodal flexible sensing solution for intelligent robotic tactile systems.