On the Evaluation of the Sensitivity Coefficient of Strain Sensors

Abstract

Sensitivity is one of the most important parameters for strain sensors. Appropriate evaluation of the sensitivity is of great significance in developing new strain sensors since, otherwise, misleading conclusions may be made. The estimation of the sensitivity coefficient of piezoresistive strain sensors based on the previously used expressions is highly dependent on the initial resistance R 0 and the sensor type (namely positive or negative). Here, it is clearly displayed that this will result in large inaccuracies in the sensitivity coefficient evaluation. Based on the modified expression by replacing R 0 with the instantaneous resistance R, the data for the sensitivity coefficient reported in literature are re‐estimated. The results reveal that most of the so‐called records reported in literature of the sensitivity coefficient are overestimated. The highest gauge factor reported so far is corrected from 1 000 000 to only 3313. On the other hand, the sensitivity coefficient for negative piezoresistive sensors is shown to be somewhat underestimated.

Ultrasoft Liquid Metal Elastomer Foams with Positive and Negative Piezopermittivity for Tactile Sensing

“…In Figure 6d, compared with the pressure sensor based on the pure elastomer foam, the capacitance changes of the sensor based on LMEF with φ = 40% increases almost seven times (from 12 to 75 pF). Although recent literature has called into question the normalization of signal by the initial signal, [7] we nevertheless report it in the inset of Figure 6d because such practices are common. We note, however, that using ΔC/C 0 for sensitivity artificially degrades the perceived performance since the initial signal in the LMEF is high relative to pure silicones or silicone foams.…”

“…However, the practice of normalizing by the initial measurement has recently been called into question because it "rewards" sensors with a low initial signal (taken to a conceptual extreme, a sensor with no initial signal would have infinite sensitivity when defined this way). [7] Stated differently, an ideal touch sensor should have both large changes in signal and large absolute signal to facilitate measurement. [8] We sought a material that could provide both and in doing so, discovered an unexpected property: negative piezopermittivity.…”

Understanding the Impact of Machine Learning Models on the Performance of Different Flexible Strain Sensor Modalities

“…1, or by using the modified Eq. 2 that reduces the influence of the signal value at zero strain (Liu et al, 2018b).…”

High-Performance Fiber-Film Hybrid-Structured Wearable Strain Sensor from a Highly Robust and Conductive Carbonized Bamboo Aerogel

“…The gauge factor (GF) of the CBA/silicone composite within the strain of 0−60% was calculated based on a modified expression of strain sensitivity. 38 As indicated in Figure S3, the average GF calculated within the strain range of 0−30 and 30− 60% is 4.0 and 30.6, respectively, which are superior to those of the conventional metallic strain gauges (GF around 2). Owing to the large fiber size and low density of the CBA, the conductive path density of the CBA/silicone composite is pretty low, which results in its high strain sensitivity.…”

“…The slope of the RCR–strain curve at higher strain is obviously larger than that at lower strain, indicating that the sensitivity of the CBA/silicone composite at large strain is higher than that at low strain. The gauge factor (GF) of the CBA/silicone composite within the strain of 0–60% was calculated based on a modified expression of strain sensitivity . As indicated in Figure S3, the average GF calculated within the strain range of 0–30 and 30–60% is 4.0 and 30.6, respectively, which are superior to those of the conventional metallic strain gauges (GF around 2).…”