In-Situ formed Quasi-Homogeneous iontronic sensors with Ultrawide sensing range for Human-Machine interaction

Flexible tactile sensors harness the properties of flexible materials to convert external stimuli into electrical signals, facilitating touch perception. They find extensive applications in health monitoring and human-machine interaction. However, traditional electrode materials have inherent limitations: capacitive tactile sensors frequently struggle to maintain a stable interface with objects, leading to potential failure under dynamic conditions and resulting in signal drift and inaccuracies. Moreover, capacitive sensors with a sandwich structure exhibit insufficient interlayer bonding, making them prone to failure under sustained shear forces. To address these limitations, we utilized a low-modulus, highly adhesive, hydrophobic organic compound, polybutyl acrylate, in combination with the ionic liquid 1-Butyl-3-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide (BMIM:TFSI), which provides excellent compatibility. This combination produced an ionogel with ultra-low modulus (similar to 13 kPa), in addition, it is conductive (similar to 0.1 S/m), transparent (>95 %), and highly adhesive with interfacial toughness of > 100 J/m(2). Furthermore, we innovatively employed an in-situ one-piece molding technology to fabricate a capacitive tactile sensor featuring a quasi-homogeneous structure and superior interlayer bonding strength which is significantly surpassing those of the reported capacitive sensors and even and even exceeding the fracture strength of the ionogel (106.57 J/m(2)). The sensor exhibited a broad sensing range, detecting stress up to 5 MPa and demonstrated high linearity (R-2 = 0.993) within the range of 50-400 kPa. After more than 2500 cycles of shear tests, the sensor maintained accurate signal output without interlayer failure. Additionally, we developed an object identification and classification robotic arm and a flexible keyboard, both incorporating this sensor, which substantially enhanced the convenience and interactivity in human-machine interaction.