Graphene‐Coated Spandex Sensors Embedded into Silicone Sheath for Composites Health Monitoring and Wearable Applications

Abstract

This study presents a low‐cost, tunable, and stretchable sensor fabricated based on spandex (SpX) yarns coated with graphene nanoplatelets (GnP) through a dip‐coating process. The SpX/GnP is wrapped into a stretchable silicone rubber (SR) sheath to protect the conductive layer against harsh conditions, which allows for fabricating washable wearable sensors. Dip‐coating parameters are optimized to obtain the maximum GnP coating rate. The covering sheath is tailored to achieve high stretchability beyond the sensing limit of 104% for SpX/GnP/SR sensors. Adjustable sensitivity is attained by manipulating SpX immersion times broadening its application for a wide range of strains: Gauge factors as high as two orders of magnitude are achieved at tensile strains greater than ≈40%. The fabricated sensors are tested for two applications: First, the SpX/GnP sensors are integrated into composite fabrics (with no negative impact on the structural integrity of the part) for screening the yarn displacements, resin flow, solidification during the hot press forming process, and structural health monitoring under mechanical loads with minimal cross‐sensitivity to temperature/humidity. Second, the capability of SpX/GnP/SP sensors in detection of a wide range of bodily motions (from the joint motion to arterial blood pressure) is demonstrated.

Application-Based Production and Testing of a Core–Sheath Fiber Strain Sensor for Wearable Electronics: Feasibility Study of Using the Sensors in Measuring Tri-Axial Trunk Motion Angles

“…There have been a few recent examples using rubber elastic support core materials with piezoresistive sheaths to create high-performance fiber sensors. The piezoresistive sheaths have been comprised of carbon nanotube forests [36,53], embedded graphene nanoplatelets [54], silver nanowires/poly(vinylidenefluoride-co-trifluoroethylene) [55], carbon nanotube–silicone rubber composites [44], and elastomer-wrapped carbon nanotube fibers [56]. However, the effect of the core material properties on sensor performance has yet to be studied for piezoresistive thermoplastic elastomer polymer composites.…”

Blood Pressure Sensors: Materials, Fabrication Methods, Performance Evaluations and Future Perspectives

“…Increasing device expected lifetime by implementing preventive measures protecting it against different causes of damage is the main objective for self-protection strategies. Coatings generally provide mechanical [396], chemical [397] and weathering [398,399] protection that increases resistance to wear, and this can be achieved through polymeric and smart coatings. Polymeric coatings (e.g., PDMS [400,401], PMMA [179,402] and PVDF [403][404][405]) can form organic thin films onto a substrate to significantly modify surface reactivity towards various elements including corrosion, adhesion, and wear [406].…”

Effect of Solvent on Segregated Network Morphology in Elastomer Composites for Tunable Piezoresistivity

“…while retaining the stretchability of the polymer matrix. [31,32] However, it is quite challenging to simultaneously achieve these properties by using the aforementioned traditional mixing methods. Therefore, several strategies, such as using 3D carbon fillers, [7,8] hybrid fillers, [7,33,34] constructing segregated network structures, [35][36][37] 3D printing [38][39][40][41][42] have been proposed to overcome these challenges.…”

“…For different strain‐sensing applications, tunable piezoresistivity, which heavily relies on controlling the deformation mechanism of the conductive network in micro‐ or nano‐scale, is usually required. As such, the filler network morphology design plays a significant role especially for composites with segregated structure .…”

“…For practical applications, it is desirable to lower the conductive filler content to augment the piezoresistive sensitivity while retaining the stretchability of the polymer matrix . However, it is quite challenging to simultaneously achieve these properties by using the aforementioned traditional mixing methods.…”