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Gauge Factor and Stretchability of Silicon-on-Polymer Strain Gauges
Center for Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX 78712, USA
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Received: 3 June 2013; in revised form: 1 July 2013 / Accepted: 2 July 2013 / Published: 5 July 2013
Abstract: Strain gauges are widely applied to measure mechanical deformation of structures and specimens. While metallic foil gauges usually have a gauge factor slightly over 2, single crystalline silicon demonstrates intrinsic gauge factors as high as 200. Although silicon is an intrinsically stiff and brittle material, flexible and even stretchable strain gauges have been achieved by integrating thin silicon strips on soft and deformable polymer substrates. To achieve a fundamental understanding of the large variance in gauge factor and stretchability of reported flexible/stretchable silicon-on-polymer strain gauges, finite element and analytically models are established to reveal the effects of the length of the silicon strip, and the thickness and modulus of the polymer substrate. Analytical results for two limiting cases, i.e., infinitely thick substrate and infinitely long strip, have found good agreement with FEM results. We have discovered that strains in silicon resistor can vary by orders of magnitude with different substrate materials whereas strip length or substrate thickness only affects the strain level mildly. While the average strain in silicon reflects the gauge factor, the maximum strain in silicon governs the stretchability of the system. The tradeoff between gauge factor and stretchability of silicon-on-polymer strain gauges has been proposed and discussed.
Keywords: piezoresistive; silicon; polymer substrate; gauge factor; stretchability
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MDPI and ACS Style
Yang, S.; Lu, N. Gauge Factor and Stretchability of Silicon-on-Polymer Strain Gauges. Sensors 2013, 13, 8577-8594.
Yang S, Lu N. Gauge Factor and Stretchability of Silicon-on-Polymer Strain Gauges. Sensors. 2013; 13(7):8577-8594.
Yang, Shixuan; Lu, Nanshu. 2013. "Gauge Factor and Stretchability of Silicon-on-Polymer Strain Gauges." Sensors 13, no. 7: 8577-8594.