High‐Performance Stretchable Strain Sensor Based on Ag Nanoparticles Sandwiched between Two 3D‐Printed Polyurethane Fibrous Textiles

Abstract

Developing stretchable strain sensors with high stretchability as well as sensitivity via a scalable technique is still a challenge that remains to be addressed. Herein, high‐performance stretchable strain sensors based on Ag nanoparticles (NPs) sandwiched between two thermoplastic polyurethane (TPU) fibrous textiles are fabricated by combining 3D‐printed TPU elastomer and solution‐coated Ag NP pulp, in which a conductive network is formed at a low loading of 4.3 wt% Ag NPs. The printed TPU fibers in each textile are arranged in parallel, while perpendicular to each other between the upper and lower textiles, forming an oblique lattice structure with their diagonal being the same direction as the external force. Under stretching, the deformed TPU fibers in the upper and lower textiles squeezed Ag NPs to undergo shearing motion, such that the disconnected electrical circuit can be compensated by some Ag NPs to retain the electrical pathway. Consequently, the printed TPU/Ag strain sensors showed high sensitivity (gauge factor of 38220 at a strain of 120–138%), wide working strain range (0–138%), and long‐term durability (>2500 cycles at 50% strain). Their promise as flexible electronic components is demonstrated in wearable motion detection systems for monitoring human motions and recognizing facial expressions.

Facile Fabrication of Highly Sensitive Thermoplastic Polyurethane Sensors with Surface- and Interface-Impregnated 3D Conductive Networks

“…As expected, other than the thickness, length, and width, the interlayer-sprayed 3D printed sample’s conductivity are higher than the overall sprayed one (Figure b). The higher conductivity is because graphene was agglomerated on the surface, which leads to high electron flow; therefore, the thickness conductivity is higher for the overall spray-coated sample. , Another important feature of 3D printed samples is that varying the infill pattern varies the property of the printed sample …”

“…The higher conductivity is because graphene was agglomerated on the surface, which leads to high electron flow; therefore, the thickness conductivity is higher for the overall spray-coated sample. 38,54 Another important feature of 3D printed samples is that varying the infill pattern varies the property of the printed sample. 55 Here, the conductive network was developed at the interface of the sample; therefore, there was a possibility for variation in conductivity based on the varying infill pattern.…”

“…Adding to the above works, another way of fabricating stretchable strain sensors is through brush-coating a conductive layer over a polymer substrate. Another polymer layer was printed over it to ensure conductive coating stability . Although this method is a low-cost and scalable fabrication process, the work has not taken full advantage of the 3D printing technique.…”

“…Another polymer layer was printed over it to ensure conductive coating stability. 38 Although this method is a low-cost and scalable fabrication process, the work has not taken full advantage of the 3D printing technique.…”

Epidermis‐Inspired Wearable Piezoresistive Pressure Sensors Using Reduced Graphene Oxide Self‐Wrapped Copper Nanowire Networks

“…The successive progress of nanomaterials synthesis and related device fabrication has ushered in many achievements in actuator/robotic devices, [ 24–27 ] energy storage devices, [ 28–30 ] biosensor devices, [ 31–34 ] flexible displays, [ 35,36 ] and human‐machine interfaces. [ 37,38 ] Several notable nanomaterials such as graphene, [ 39,40 ] metal nanoparticles (particularly liquid metal), [ 41–43 ] conductive polymers, [ 44,45 ] and metal nanowires/nanofibers [46,47] have been extensively exploited for developing next‐generation wearable electronic devices. Metal nanowires have garnered significant attention among these candidate materials because of their excellent electrical, mechanical, and optical properties.…”