Piezoresistivity and piezoelectricity discovered in aluminum, with relevance to structural self-sensing

Publication date: Available online 22 February 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Xiang Xi, D.D.L. ChungAbstractThis work provides the first report of piezoresistivity and piezoelectricity in aluminum, as observed in the in-plane direction for aluminum foil and Al 2024-O alloy bar, which exhibit similar properties, though the piezoelectricity of the latter is slightly stronger. These phenomena enable structural self-sensing and multifunctionality. The stress (≤66 MPa) and strain (≤0.096%) are in the elastic regime. The piezoresistivity is strong and negative, with gage factor -1630, and provides electrical-resistance-based stress/strain sensing. The resistance (DC) decreases monotonically and reversibly with increasing tensile stress, with the fractional decrease being up to 13%. The in-plane electric field (DC) decreases monotonically and reversibly with increasing tensile stress, with the fractional decrease being up to 29%. The capacitance (2 kHz) increases monotonically and reversibly with increasing tensile stress, with the fractional increase being up to 10%. The capacitance increase (up to 10%) relates to the increase in the relative permittivity (up to 15%). The relative permittivity is high, at 5.48 × 104 (2 kHz) in the absence of stress. The piezoelectricity is weak, with the piezoelectric coupling coefficient d33 being -1.4 × 10-8 pC/N, the electric field output contributing -1.7 × 10-8 pC/N, the relative permittivity i...
Source: Sensors and Actuators A: Physical - Category: Physics Source Type: research
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