Near-Linear Responsive and Wide-Range Pressure and Stretch Sensor Based on Hierarchical Graphene-Based Structures via Solvent-Free Preparation

Abstract

Flexible and wearable electronics have huge potential applications in human motion detection, human–computer interaction, and context identification, which have promoted the rapid development of flexible sensors. So far the sensor manufacturing techniques are complex and require a large number of organic solvents, which are harmful not only to human health but also to the environment. Here, we propose a facile solvent-free preparation toward a flexible pressure and stretch sensor based on a hierarchical layer of graphene nanoplates. The resulting sensor exhibits many merits, including near-linear response, low strain detection limits to 0.1%, large strain gauge factor up to 36.2, and excellent cyclic stability withstanding more than 1000 cycles. Besides, the sensor has an extraordinary pressure range as large as 700 kPa. Compared to most of the reported graphene-based sensors, this work uses a completely environmental-friendly method that does not contain any organic solvents. Moreover, the sensor can practically realize the delicate detection of human body activity, speech recognition, and handwriting recognition, demonstrating a huge potential for wearable sensors.

Porous Graphene Composite Polymer Fibres

“…Graphene sheets were found to have new and unique properties such as being able to absorb a larger than normal fraction of incident white light (photoacoustic absorption of 2.3%), having very high thermal conductivity between 4840 to 5300 W/mK, electrical conductivity of up to 2000 S/cm and a Young’s modulus of over 1 TPa [ 3 , 4 , 5 , 6 ]. Because of these excellent properties relating especially to its optical, thermal, electrical and mechanical features, graphene is potentially a superior replacement medium for current industrial application standards, such as in semiconductors, electromagnetic shielding, healthcare, high-bandwidth wiring systems, fibre optics, material reinforcement and even heat dissipation for advanced hardware cooling [ 7 , 8 , 9 , 10 , 11 , 12 ]. Graphite is desirable in the single graphene sheet level as the excellent properties become even more pronounced [ 13 ].…”

Enhanced Thermal Conductivity of Epoxy Composites Filled with Al2O3/Boron Nitride Hybrids for Underfill Encapsulation Materials

“…Consequently, a low CTE is required. Moreover, dissipation of the heat is generated in the chip by conducting heat to the substrate; hence, high thermal conductivity is essential [ 2 , 8 ]. Lastly, the procedure is time-consuming and costly.…”

“…Recently, the realization of heat dissipation has become the focus of electronic encapsulation and the study of underfill, which is one of the most recent techniques in this area. In the future, an ideal underfill should not only possess high thermal conductivity, but also a low coefficient of thermal expansion (CTE) because underfilling enhances the connection strength of electrical contacts and compensates for differences in the thermal expansion rates of two joining materials, which could lead to product failure [ 8 ].…”

Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

“…Using graphene nanoplatelets deposited on a PDMS coated polyethylene terephthalate (PET) film, Wang et al [ 191 ] created a stretch sensor that was subjected to 1000 bending loads. The sensor exhibited linearity to 30% strain with a GF of 36.2.…”

“…The sensor exhibited minimal electrical hysteresis and rapid response. Additionally, the sensor recovered from the bending fatigue and did not exhibit signs of material failure [ 191 ].…”