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Development of capacitive nanoparticle-based strain sensors

To deploy networks of connected sensors at large scale in embedded systems, it is mandatory to use wireless sensors with low power consumption. Helped by his strong knowledge and experience with resistive nanoparticle-based strain sensors, the Nanotech team studied the fabrication of capacitive nanoparticle-based strain sensors.

Owing to an analytic model, the sensor design has been optimized in order to maximize the capacitor of the active area (most of the time neglected because of its low value) which is composed of a monolayered assembly of gold nanoparticles realized by CSA. This study revealed that an active area of 1mm² addressed by interpenetrating electrodes was capable of reaching reliable capacitors > 1pF.

The electromechanical study of these sensors using 14 nm gold nanoparticles demonstrated sensitivity 5 times higher compared to conventional capacitive gauges (Figure 1). The proof that a simple low cost circuit coupled with a microcontroller is capable of realizing the measurements on these gauges opens new promising paths on the feasibility of a new entirely wireless set-up.

Figure 1 : (a) Optical images by SEM of a capacitive nanoparticle-based strain sensors, (b) Typical electromecanical results as a function of the nanoparticle size used (7nm, 12nm et 14nm)