School of Engineering Science, University of Science and Technology of China: New Progress in Continuum Tactile Sensing Based on Liquid Metal

Multimodal tactile perception is a key capability for humanoid robots to achieve dexterous manipulation, human-robot interaction, and environmental adaptation. However, traditional flexible electronic skins, which rely primarily on discrete sensor arrays, face inherent bottlenecks such as complex wiring, limited flexibility, and poor mechanical reliability at soft-hard interfaces. To overcome these challenges, the research team innovatively proposed a new concept of "continuum tactile sensing," which enables continuous perception of multiple tactile modalities—including pressure, position, and sliding—through a single, unstructured liquid metal interface, thereby significantly simplifying system architecture.

The study found that the electrical double-layer (EDL) voltage at the liquid metal interface dynamically changes with mechanical deformation. More importantly, when conductive graphite contacts the liquid metal, the tactile signal undergoes a synergistic amplification of over 100 times due to interfacial charge transfer effects, transforming the otherwise weak interfacial response into a highly sensitive and stably readable electrical signal. This "contact amplification" mechanism provides an entirely new underlying principle for high-performance flexible tactile sensing.

Building on this unique signal amplification mechanism, the team further developed a geometrically encoded dual-channel sensing strategy, achieving high-precision two-dimensional position localization and eight-direction sliding trajectory recognition on a 5 × 5 cm liquid metal plane. Unlike conventional array-based electronic skins, this system does not require pixelated sensing units; instead, it relies solely on a continuous interface to accomplish spatial tactile localization and motion direction analysis, demonstrating the distinctive advantages of "array-free" tactile perception. The team also constructed a humanoid robot tactile demonstration system, which, by analyzing tactile signals in real time, enables reconstruction of complex action sequences and further drives an LED array for visual feedback validation, showcasing the application potential of this technology in human-robot interaction systems.

This study establishes a novel tactile sensing paradigm based on a continuous liquid metal interface, offering a new technological pathway for the next generation of electronic skins for humanoid robots. In the future, this technology is expected to be applied in areas such as humanoid robot tactile systems and wearable devices, endowing robots with continuous tactile perception and environmental interaction capabilities that more closely resemble human skin.