Hierarchical Wrinkles for Tunable Strain Sensing Based on Programmable, Anisotropic, and Patterned Graphene Hybrids

Abstract

Flexible, stretchable, wearable, and stable electronic materials are widely studied, owing to their applications in wearable devices and the Internet of Things. Because of the demands for both strain-insensitive resistors and high gauge factor (GF) strain-sensitive materials, anisotropic strain sensitivity has been an important aspect of electronic materials. In addition, the materials should have adjustable strain sensitivities. In this work, such properties are demonstrated in reduced graphene oxide (RGO) with hierarchical oriented wrinkle microstructures, generated using the two-step shrinkage of a rubber substrate. The GF values range from 0.15 to 28.32 at 100% strain. For device demonstrations, macrostructure patterns are designed to prepare patterned wrinkling graphene at rubber substrate (PWG@R). Serpentiform curves can be used for the constant-value resistor, combined with the first-grade wrinkles. Strip lines can increase the strain-sensing property, along with the second-grade wrinkles. The patterned sensor exhibits improved GF values range from 0.05 to 49.5. The assembled sensor shows an excellent stability (>99% retention after 600 cycles) with a high GF (49.5). It can monitor the vital signs of the throat and wrist and sense large motions of fingers. Thus, PWG@R-based strain sensors have great potential in various health or motion monitoring fields.

Efficient Fabrication of Carbon Nanotube‐Based Stretchable Electrodes for Flexible Electronic Devices

“…The shrinking of the elastic substrate could induce the formation of a wrinkled topography. The contraction modes of the elastic substrate include thermal shrinking, [23][24][25] swelling, [26][27][28] pre-stretching, [29][30][31][32][33][34] and so on. Among them, thermal shrinking and swelling can obtain uniform wrinkle structures but with a low shrinkage ratio and poor controllability.…”

“…In this study, based on the previous works of our group, [34,36,37] a simple shrinking method was proposed to prepare a CNT-based stretchable electrode. The electrode was fabricated by coating a CNT aqueous dispersion on an inflated latex balloon, drying, and deflating.…”

Printing Polymeric Convex Lenses to Boost the Sensitivity of a Graphene-Based UV Sensor

“…Hence, precise measurement is greatly important to properly exploit the advantages of UV [ 1 , 2 , 3 ]. Among measurement methods, the use of graphene (GP) for UV sensing has received great attention for its lightweight, superior electrical and mechanical properties [ 4 , 5 , 6 ], chemo-functionality [ 7 , 8 ], and quick opto-response [ 9 , 10 ]. To overcome the sensor’s aboriginal capabilities, various techniques to improve sensitivity have recently been suggested.…”