Sub-millimeter scale 3D integration strategy enables ultrahigh-density and ultralow-crosstalk flexible tactile sensor array for robotic e-skin application

Abstract

The rapid development of intelligent robots and wearable electronics brings great demand for flexible tactile sensor arrays with high sensitivity, fast response and high spatial resolution. However, simultaneously achieving high sensing performance and low crosstalk remains a fundamental challenge as sensor unit size is further reduced and array density increases. This work proposes a novel design and assembly strategy based on a mechanical microlattice structure, combined with in-situ laser direct writing and batch transfer techniques, to address the challenges from sub-millimeter active material array fabrication to 3D tactile sensor array integration. Additionally, the one-step preparation of high-consistency microcones on flexible substrates during laser direct writing enables the sensor to achieve a high sensitivity of 2.68 kPa−1 and a rapid response time of 50 ms. Both finite element simulation and experiments validate that the meticulously engineered mechanical microlattice structure, which incorporates a multi-material Young’s modulus gradient design, effectively concentrates external pressure on the pressed sensor units while shielding unpressed units, significantly mitigating the crosstalk and facilitating an ultrahigh resolution of ∼ 1 mm. Finally, the multipoint precision detection capability of the fabricated ultrahigh-density (over 113 units/cm2) tactile sensor array is verified as robotic e-skin for object grasping and pattern recognition.