Flexible tactile sensors enabled by biomimetic microstructures: From transduction mechanisms to human-integrated applications

Flexible tactile sensors enable applications requiring intimate mechanical contact with soft tissues or conformable integration on deformable robotic surfaces. Despite extensive exploration of functional materials, performance remains frequently constrained by inefficient stress transfer and unstable interfacial contact within conventional planar architectures. The incorporation of biomimetic microstructures offers a versatile strategy to simultaneously modulate mechanical deformation and electrical signal evolution. Hierarchical geometries inspired by human skin, fibrous tissues, and natural surfaces reshape local strain distribution and interfacial contact dynamics, thereby governing the overall electromechanical transduction efficiency. Rather than relying exclusively on intrinsic material conductivity or dielectric permittivity, structural engineering emerges as a powerful parameter for signal amplification. In this review, we first outline the fundamental working principles and key characteristics of piezoresistive, capacitive, piezoelectric, and triboelectric tactile sensors. We then survey representative biomimetic geometric designs and elucidate how their mechanical behavior translates into enhanced electrical performance. Fabrication approaches are critically evaluated with respect to scalability, reproducibility, and compatibility with large-area processing. Finally, we discuss outstanding challenges concerning structural durability, system integration, and long-term environmental reliability.