Large-Area Carbon\nNanotube-Based Flexible Composites\nfor Ultra-Wide Range Pressure Sensing and Spatial Pressure Mapping

Abstract

Flexible pressure sensors are of broad interest for applications\nincluding human–machine interfaces, wearable electronics, and\nobject/motion detection. However, complexities associated with constituent\nmaterials, fabrication processes, sensing mechanisms, and hardwiring\noften hinder the large-scale applications of using high performance\npressure sensors reported in the literature. Here we demonstrate a\nlarge-area, highly flexible, conformable, and mechanically robust\npressure sensor using a silicone elastomer with an embedded nonwoven\ntextile carrier coated with carbon nanotubes. The selected silicone\npolymer allows through-thickness deformability of the sensor while\nthe high modulus textile carrier ensures in-plane stiffness and stability.\nThe sensor has an initial electrical conductivity of 4.4 ± 0.38\nS/m and is fabricated using a straightforward dip coating and polymer\ninfusion process and can be easily scaled-up for large-scale applications.\nOn the basis of its hierarchical composite structure, this piezoresistive\npressure sensor possesses extremely high resilience under compression,\na repeatable monotonic positive pressure correlation, and an ultrawide\nelastic working range (5.5 ± 0.5 MPa) that can be segmentally\nlinearized. A true two-dimensional modality for spatial pressure mapping\nis realized by utilizing electrical impedance tomography (EIT) and\ndemonstrated to yield conductivity maps that can estimate the location,\nshape, and amplitude of both localized and distributed pressure with\nsimple contact areas.