Minimizing the wiring in distributed strain sensing using a capacitive sensor sheet with variable-resistance electrodes

Abstract

Strain mapping over a large area usually requires an array of sensors, necessitating extensive and complex wiring. Our solution is based on creating multiple sensing regions within the area of a single capacitive sensor body by considering the sensor as an analogical transmission line, reducing the connections to only two wires and simplifying the electronic interface. We demonstrate the technology by using piezoresistive electrodes in a parallel plate capacitor that create varying proportions of electromagnetic wave dissipation through the sensor length according to the interrogation frequency. We demonstrate, by a sensor divided into four virtual zones, that our cracked capacitive sensor can simultaneously record strain in each separated zone by measuring the sensor capacitance at a high frequency. Moreover, we confirm that by changing the frequency from high to low, our sensor is able to measure the local strain amplitudes. This sensor is unique in its ability to monitor strain continuously over a large area with promoted spatial resolution. This sensing technology with a reduced number of wires and a simple electronic interface will increase the reliability of sensing while reducing its cost and complexity.

Distributed sensing along fibers for smart clothing

“…Unlike approaches using multiple sensors connected by wires, multiplexers, or switches, the electrical connectivity is greatly simplified (16,17). Distributed sensing can also be used to increase sensitivity (18,19), allow arbitrarily high spatial resolution (20), and simplify twodimensional (2D) pressure or strain sensitive arrays (16,20,21). Capacitive strain sensors have garnered recent interest because the configuration is possible in yarn, coaxial, or twisted fiber form and has linear response to strain, which is ideal for integration into textiles (22)(23)(24)(25).…”

“…Distributed strain sensing has been shown with promising bench tests using chains of soft capacitive strain sensors ( 17 ). Segmented soft capacitive sensors can be used to isolate strain at individual segments through microfracturing of piezoresistive electrodes ( 19 ). Distributed pressure sensitive arrays have been demonstrated using frequency domain measurements of resistor-inductor-capacitor (RLC) resonator chains with a breadth of sensing applications ( 26 ).…”