Flexible Waterborne Polyurethane/Cellulose Nanocrystal Composite Aerogels by Integrating Graphene and Carbon Nanotubes for a Highly Sensitive Pressure Sensor

Abstract

Flexible piezoresistive sensors with high sensitivity, low cost, and wide response ranges are urgently required due to the rapid development of wearable electronics. Here, carbon nanotubes (CNTs)/graphene/waterborne polyurethane (WPU)/cellulose nanocrystal (CNC) composite aerogels (CNTs/graphene/WC) were fabricated by facile solution mixing and freeze-drying technology for high-performance pressure sensors. WPU and CNC were constructed as a 3D structure skeleton, and the synergistic effect of CNTs and graphene was beneficial to enhancing the sensing performance. The obtained pressure sensor exhibits a highly porous network structure, remarkable mechanical properties (76.16 kPa), high sensitivity (0.25 kPa–1), an ultralow detection limit (0.112 kPa), and high stability (>800 cycles). More importantly, the piezoresistive sensor could be successfully used to detect various human motions such as finger bending, squatting–rising, walking, and running and effectively extract real-time information by the electrical signals. In addition, the CNTs/graphene/WC composite aerogel exhibits excellent thermal insulation performance, which can withstand 160 °C for a long time without any damage to the structure. The CNTs/graphene/WC composite aerogel, because of its thermal insulation property, endows the sensor with the potential for application in high-temperature environments. The results indicate that CNTs/graphene/WC composite aerogels possess high sensing performance and outstanding thermal insulation, which means that the aerogels could be used as flexible, wearable electronics.

Pressure‐Perceptive Actuators for Tactile Soft Robots and Visual Logic Devices

“…Detailed comparisons are listed in Table S1 (Supporting Information). [ 29–38 ] These results indicate that CNT–Silk/BOPP composite films can be used in pressure‐sensing devices for further applications.…”

Sustainable Approach for Developing Graphene-Based Materials from Natural Resources and Biowastes for Electronic Applications

“…A facile solution mixing along with the freeze-drying approach was used to make CNTs/graphene/WC (WPU/CNC) nanocomposite aerogels for pressure sensors having high efficacy. CNTs and graphene’s synergistic effect demonstrated the enhanced sensing capability of cellulose nanocrystal (CNC) and waterborne polyurethane (WPU), being built as a 3D framework . Combining graphene and CNTs (as conductive materials) with polymeric materials to create a nanocomposite aerogel is the healthiest approach for constructing flexible sensors .…”

“…CNTs and graphene's synergistic effect demonstrated the enhanced capability of cellulose nanocrystal (CNC) and waterborne polyurethane (WPU), being built as a 3D framework. 189 Combining graphene and CNTs (as conductive materials) with polymeric materials to create a nanocomposite aerogel is the healthiest approach for constructing flexible sensors. 190 rGO has been widely researched among electrocatalytically active materials because of its distinctive mechanical surface, electrical characteristics, and hydrophilicity, which promote dispersion.…”

Mechanically Robust and Elastic Graphene/Aramid Nanofiber/Polyaniline Nanotube Aerogels for Pressure Sensors

“…Aerogels are attracting more and more attention attributed to their continuous porous network structures, low density, and high specific surface area, promising in a variety of applications, such as absorbents, light-weight structural materials, catalysis, energy storage devices, and sensors. − A variety of aerogels have been prepared generally from inorganic small molecules (such as silica), polymer, − MXene, , carbon materials (such as graphene and carbon nanotubes), , and so on. Graphene-based aerogels, as one of the typical carbon-based aerogels, possess high conductivity and large specific surface area, showing great potential in the applications as supercapacitors, batteries, and sensors, comparing to polymer aerogels with low electrical conductivity.…”