Electronic Thesis/Dissertation


Highly Sensitive Wearable Piezoelectric Force Sensor with Quasi-Static Load Testing Open Access

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This work proposes to develop a wearable piezoelectric sensor that can be integrated into clothing and can measure high levels of forces. The final design utilized a piezoelectric film known as polyvinylidene fluoride (PVDF). Based on the direct piezoelectric effect, good linearity is expected such that there should be an increase in voltage as higher loads are tested. A rigorous set of trials determined the sensitivity, repeatability, and versatility of the sensor by observing the percent errors to deduce the accuracy and precision of these measurements. With an external electrical circuit and an interface to a computer, measurements sampled at 16ms includes calculations for initial voltage, force, pressure, and normalized voltage as well as measured voltage via portable multimeter. Primary results will be gathered analyzed based on two criteria: First, different test conditions such as no-cloth, rigid-cloth, and smooth-cloth implementations; and second, varying sensor dimensions such as approximately 2 in. by 2 in.to measure up to 19 MPa and approximately 1.25 in. by 1.25 to measure up to 50 MPa. Moreover, the applied load on the sensor will be divided into the following two ranges: The low-force threshold between 2.5 kN and 10 kN with steps of 0.5 kN, and the high-force threshold between 10 kN and 50 kN with steps of 2.5 kN. Given all these test conditions, all results have shown that the proposed sensor can measures applied loads with great accuracy since all percent errors are well within the minimum performance error threshold of 2%, if not below the maximum error of 5%.Through further design optimization in sensor, circuit, and software design, the proposed research demonstrates the potential for a cost-effective yet highly sensitive force sensor for multiple applications.

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