Pressure mapping using a smart nanocomposite foam and electrical impedance tomography

Contact pressure sensing and pressure mapping are commonly used in many automotive, healthcare, industrial, and robotics applications. Many commercially available pressure mapping solutions use a dense array of transducers embedded in a pad. However, the pad is relatively thick with noticeable rigid components, and high-resolution pressure mapping systems can be complex, cumbersome, bulky, expensive, and not portable. Thus, the objective of this study was to validate pressure mapping using a commercial Smartfoam interrogated using an electrical impedance tomography (EIT) measurement strategy and algorithm. In addition, the sensitivity of the Smartfoam was enhanced by depositing on its surface a piezoresistive carbon nanotube-based thin film. EIT electrodes were installed along the foam boundaries, thereby eliminating the need for any electrodes or rigid objects on the foam and pressure mapping surface. A custom data acquisition system was employed to apply electrical current excitations while measuring the boundary voltage response across pairs of boundary electrodes. The boundary voltage datasets were used for solving the EIT inverse problem to reconstruct the conductivity distribution of the specimen. Controlled pressure mapping tests were performed by placing different weights of varying contact areas on different positions of the nanocomposite Smartfoam. The EIT results confirmed that the nanocomposite Smartfoam could resolve pressure hotspots at different locations, as well as different magnitudes of contact pressure applied. Real-time pressure mapping was successfully demonstrated, while pressure mapping resolution and accuracy were also characterized. Overall, the system is lightweight, low-profile, and does not use rigid components on the foam surface. Future work will align this method for targeted consumer and healthcare applications.