Large-Area Carbon Nanotube-Based Flexible Composites for Ultra-Wide Range Pressure Sensing and Spatial Pressure Mapping

Abstract

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

Flexible Liquid‐Filled Fiber Adapter Enabled Wearable Optical Sensors

“…Thus, these flexible and stretchable electronic devices are also known as electronic skins (E-skins). Enabled by advanced nanomaterials, including carbon nanotubes, [21,22] graphene, [23,24] noble metal nanowires, [25,26] and polymer nanofibers, [27,28] and/or bioinspired microstructures, [29][30][31][32][33][34] E-skins are already capable of providing enhanced performance over human skins, both in spatial resolution and thermal sensitivity. [35] However, parasitic effect, insufficient insulation, and electromagnetic disturbances may limit their applications, to some extent.…”

Recent Progress in Flexible Tactile Sensors for Human‐Interactive Systems: From Sensors to Advanced Applications

“…Diverse nanomaterials have been studied for use as a conductive material, that is, 0D materials (e.g., metal nanoparticles [16] ), 1D materials [e.g., metal nanowires (NWs) [17] and CNTs [18] ], and 2D materials (e.g., reduced graphene oxide (rGO) [19] and MXene [20] ). As a matrix component, various polymers (polydimethylsiloxane (PDMS) [21] and Ecoflex [22] ) and textiles (cotton [23] and polyester [24] ) have been used. Resistive tactile sensors have advantages such as high sensitivity, simple device structure, and a facile fabrication process; however, high power consumption is regarded as drawbacks.…”

Structural engineering from an inverse problems perspective

“…Further on the topic of polymer-based composites, thin pressure sensors were produced by embedding a non-woven textile modified with CNTs into a soft elastomer. EIT was then employed to visualize various pressure distributions including non-uniform distributions [278]. EIT was also recently applied for damage detection in a ceramicbased composite that was modified with micrometre-sized waste-iron particles [279].…”