We designed, produced and characterized new capacitive strain sensors based on colloidal gold nanoparticles. The active area of these sensors, made up of a 1 mm2 close-packed assembly of gold nanoparticles between interdigitated electrodes, was designed to achieve measurable capacitance (>∼1 pF) and overcome parasitic capacitances. Electro-mechanical experiments revealed that the sensitivity of such capacitive sensors increases in relation to the size of the nanoparticles. In the case of 14 nm gold NPs, such sensors present a relative capacitance variation of -5.2% for a strain of 1.5%, which is more than 5 times higher than that observed for conventional capacitive strain gauges. The existence of two domains (pure capacitive domain and mixed capacitive-resistance domain) as a function of the frequency measurement allows for the adaptation of sensitivity of these capacitive sensors. A simple low-cost circuit based on a microcontroller board was finally developed to detect the capacitance variations of such NP based strain sensors. This low-cost equipment paves the way for the development of an entirely wireless application set-up.

Accurate wireless strain monitoring is critical for many engineering applications. Capacitive strain sensors are well suited for remote sensing but currently have a limited sensitivity. This study presents a new approach for improving the sensitivity of electrical capacitance change-based strain sensors. Our technology is based on a dielectric elastomer layer laminated between two fragmented electrodes (i.e., carbon nanotube papers) that, by design, experiences a significant change in resistance (from Ω to MΩ) when stretched and makes the sensor behave as a transmission line, a well-known structure in telecommunication engineering. The strain-dependent voltage attenuation over the structure length results in a large variation of the effective capacitance (gauge factor exceeding 37 at 3% strain).

Sensing the motion of objects and humans is essential for various applications, including human‐machine interfaces. Over the past few years, motion sensing has been extensively studied using capacitive strain sensors that can be utilized for wireless communications. The performance and functionality of capacitive strain sensors have been improved by achieving high sensitivity, large‐area sensing, ultra‐stretchability, and simplicity in design, measurement methods, and wireless integration. This review article highlights recent developments in capacitive strain sensors, including their characteristics and applications. First, the mechanisms and techniques employed to enhance the sensitivity of capacitive strain sensors are reviewed. Then, the notable features of this sensing strategy are highlighted, such as its ability to cover a wide area, properties of the required electronic interface, and sensor implementation inside a remote measurement system via an oscillating circuit. Therefore, a global review of the capacitive strain sensor that has been previously attempted can participate in developing an effective sensing method to meet the market need.