Yazdi Armin, Tsai Li-Chih, Salowitz Nathan P
Department of Civil and Environmental Engineering, University of Wisconsin Milwaukee, Milwaukee, WI 53211, USA.
Department of Biomedical and Health Informatics, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
Sensors (Basel). 2024 Sep 4;24(17):5739. doi: 10.3390/s24175739.
This paper presents a recent investigation into the electromechanical behavior of thermally reduced graphene oxide (rGO) as a strain sensor undergoing repeated large mechanical strains up to 20.72%, with electrical signal output measurement in multiple directions relative to the applied strain. Strain is one the most basic and most common stimuli sensed. rGO can be synthesized from abundant materials, can survive exposure to large strains (up to 20.72%), can be synthesized directly on structures with relative ease, and provides high sensitivity, with gauge factors up to 200 regularly reported. In this investigation, a suspension of graphene oxide flakes was deposited onto Polydimethylsiloxane (PDMS) substrates and thermally reduced to create macroscopic rGO-strain sensors. Electrical resistance parallel to the direction of applied tension (x^) demonstrated linear behavior (similar to the piezoresistive behavior of solid materials under strain) up to strains around 7.5%, beyond which nonlinear resistive behavior (similar to percolative electrical behavior) was observed. Cyclic tensile testing results suggested that some residual micro-cracks remained in place after relaxation from the first cycle of tensile loading. A linear fit across the range of strains investigated produced a gauge factor of 91.50(Ω/Ω)/(m/m), though it was observed that the behavior at high strains was clearly nonlinear. Hysteresis testing showed high consistency in the electromechanical response of the sensor between loading and unloading within cycles as well as increased consistency in the pattern of the response between different cycles starting from cycle 2.
本文介绍了一项最近对热还原氧化石墨烯（rGO）作为应变传感器的机电行为的研究。该应变传感器承受高达20.72%的反复大机械应变，并在相对于施加应变的多个方向上测量电信号输出。应变是所感知的最基本和最常见的刺激之一。rGO可以由丰富的材料合成，能够承受大应变（高达20.72%），可以相对容易地直接在结构上合成，并且具有高灵敏度，经常报道的应变片系数高达200。在这项研究中，将氧化石墨烯薄片的悬浮液沉积到聚二甲基硅氧烷（PDMS）基板上并进行热还原，以制造宏观的rGO应变传感器。与施加张力方向平行（x^）的电阻在应变约7.5%之前表现出线性行为（类似于固体材料在应变下的压阻行为），超过该应变后观察到非线性电阻行为（类似于渗流电行为）。循环拉伸测试结果表明，在从第一次拉伸加载循环松弛后，一些残余微裂纹仍然存在。在所研究的应变范围内进行线性拟合得到的应变片系数为91.50(Ω/Ω)/(m/m)，不过观察到高应变下的行为明显是非线性的。滞后测试表明，传感器在循环内加载和卸载之间的机电响应具有高度一致性，并且从第2个循环开始，不同循环之间的响应模式一致性增加。
