Wearable Strain Sensors Based on a Porous Polydimethylsiloxane Hybrid with Carbon Nanotubes and Graphene

Abstract

High-performance flexible strain sensors are urgently needed with the rapid development of wearable intelligent electronics. Here, a bifiller of carbon nanotubes (CNTs) and graphene (GR) for filling flexible porous polydimethylsiloxane (CNT-GR/PDMS) nanocomposites is designed and prepared for strain-sensing applications. The typical microporous structure was successfully constructed using the Soxhlet extraction technique, and the connected CNTs and GR constructed a perfect threedimensional conductive network in the porous skeleton. As a result, the stretchability and sensitivity of the CNT-GR/PDMS-based strain sensors were well regulated based on the porous structure and the typical synergistic conductive network. Based on the destruction effect of the brittle synergistic conductive network located in the outer and inner layers of the cell skeleton and the contact effect between adjacent cells in different strain ranges, the prepared CNTs-GR/PDMS-based strain sensor exhibited superior gauge factors of 182.5, 45.6, 70.2, and 186.5 in the 0−3, 3−57, 57−90, and 90−120% strain regions, respectively. In addition, this material also exhibited an ultralow detection limit (0.5% strain), a fast response time (60 ms), good stability and durability (10,000 cycles), and frequency-/strain-dependent sensing performances, making it active for the detection of various external environments. Finally, the prepared porous CNTs-GR/PDMS-based strain sensor was attached to the skin to detect various human motions, such as wrist bending, finger bending, elbow bending, and knee bending, thereby demonstrating wide application prospects in smart wearable devices.

Electrically Conductive Networks from Hybrids of Carbon Nanotubes and Graphene Created by Laser Radiation

“…Significant advances have been made in the creation of hybrid materials that include CNTs and graphene/graphene oxide sheets due to the complementary structural and electrophysical features of two nanocarbon modifications. Using created hybrids of CNT and graphene sheets, such promising devices as intelligent wearable devices (IWDs) are being developed [ 46 , 47 , 48 ]. No less promising areas of CNT and graphene hybrids application are efficient batteries, supercapacitors, conducting channels, field emitter devices, and other electronic and optical devices.…”

“…Properties of such CNT/graphene heterostructures have been studied in many works [ 49 , 50 , 51 , 52 , 53 , 54 , 55 ]. Hybrid-based composites have high electrical conductivity and are used as flexible strain gauges [ 46 ], heating elements [ 48 ], and flexible capacitors [ 56 ]. In supercapacitors based on CNT/graphene hybrid composites, condensing properties are provided by nanotubes.…”

Cost-Effective Fabrication of Transparent Strain Sensors via Micro-Scale 3D Printing and Imprinting

“…Flexible strain sensors play an important role in applications such as health monitoring [ 1 , 2 , 3 ], electronic skin [ 4 , 5 , 6 ], wearable devices [ 7 , 8 , 9 , 10 , 11 , 12 ], and human-computer interactions [ 13 ]. Piezoresistive strain sensors have played an important role in the field of flexible strain sensors due to their simple reading mechanism.…”

A DIY Fabrication Approach of Stretchable Sensors Using Carbon Nano Tube Powder for Wearable Device

“…Soft robotics and soft wearable sensors are receiving increased attention due to their potential applications such as for rehabilitation or assistance purposes ( Wehner et al, 2013 ; Polygerinos et al, 2015 ), human health monitoring systems ( Ramasamy and Balan, 2018 ; He et al, 2021 ), human-machine interactions ( Zoss et al, 2006 ; Banala et al, 2008 ; Roh et al, 2015 ), and human motion monitoring ( Yang et al, 2018 ). Many soft actuator devices have already been developed.…”