Piezoresistivity is an electromechanical effect characterized by the reversible change in the electrical resistivity with strain. It is useful for electrical-resistance-based strain/stress sensing. The resistivity can be the volumetric, interfacial or surface resistivity, though the volumetric resistivity is most meaningful scientifically. Because the irreversible resistivity change (due to damage or an irreversible microstructural change) adds to the reversible change that occurs at lower strains, the inclusion of the irreversible effect makes the piezoresistivity appear stronger than the inherent effect. This paper focuses on the inherent piezoresistivity that occurs without irreversible resistivity changes. The effect is described by the gage factor (GF), which is defined as the fractional change in resistance per unit strain. The GF can be positive or negative. Strong piezoresistivity involves the magnitude of the fractional change in resistivity much exceeding the strain magnitude. The reversible effect of strain on the electrical connectivity is the primary piezoresistivity mechanism. Giant piezoresistivity is characterized by GF ≥ 500. This critical review with 209 references covers the theory, mechanisms, methodology and status of piezoresistivity, and provides the first review of the emerging field of giant piezoresistivity. Piezoresistivity is exhibited by electrically conductive materials, particularly metals, carbons and composite materials with conductive fillers and nonconductive matrices. They include functional and structural materials. Piezoresistivity enables structural materials to be self-sensing. Unfortunately, GF was incorrectly or unreliably reported in a substantial fraction of the publications, due to the pitfalls systematically presented here. The most common pitfall involves using the two-probe method for the resistance measurement.

中文翻译：

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压阻性及其在基于电阻的应变传感中的应用的批判性评论

压阻是一种机电效应，其特征在于电阻率随应变发生可逆变化。它可用于基于电阻的应变/应力传感。电阻率可以是体积电阻率、界面电阻率或表面电阻率，尽管体积电阻率在科学上最有意义。因为不可逆的电阻率变化（由于损坏或不可逆的微观结构变化）增加了在较低应变下发生的可逆变化，包含不可逆效应使得压阻率看起来比固有效应更强。本文重点介绍在没有不可逆电阻率变化的情况下发生的固有压阻。该效应由应变系数 (GF) 描述，其定义为每单位应变电阻的分数变化。GF 可以是正数或负数。强压阻涉及电阻率的分数变化幅度远远超过应变幅度。应变对电连接的可逆影响是主要的压阻机制。巨压阻的特点是 GF ≥ 500。这篇包含 209 篇参考文献的批判性评论涵盖了压阻的理论、机制、方法论和现状，并首次对巨压阻新兴领域进行了综述。导电材料表现出压阻性，特别是金属、碳和具有导电填料和非导电基质的复合材料。它们包括功能材料和结构材料。压阻性使结构材料能够自我感应。很遗憾，由于这里系统地呈现的缺陷，GF 在大部分出版物中被错误或不可靠地报道。最常见的陷阱是使用双探针法进行电阻测量。