Doctor of Philosophy, University of Akron, 2020, Mechanical Engineering

Soft and stretchable electronics will play an important role in the areas of robotics, prosthetics, wearables, and energy harvesting devices. The emergence of smart technologies is spurring the development of a wider range of applications for stretchable and conformable pressure sensors. Concomitant with the material research on soft sensors, the fabrication method is also gaining major progress. The manufacturing and design flexibility offered by additive manufacturing (AM) may enable the fabrication of sensors that are superior to those fabricated by conventional manufacturing techniques. AM could realize applications of the sensors which are difficult to achieve via a conventional method. In this work, a flexible and stretchable pressure sensor has been proposed. A pressure-sensitive membrane was fabricated through the polymerization of an ionic liquid (IL)-prepolymer blend. Stretchable conductive strips or electrodes were fabricated using a carbon nanotube (CNT)/polymer composite. The IL-based pressure-sensitive layer was sandwiched between CNT–based stretchable electrodes and encapsulated within stretchable top and bottom insulating layers. The multi-layer multi-material sensor was first fabricated through a screen-printing and molding process for evaluation and characterization purposes. Sensor performance was investigated for different degrees of crosslinking and polymerization, concentrations of IL, and thicknesses of the IL/polymer layer. The experimental results showed that these variables affect the sensitivity of the sensor. Next, various forces were applied to a screen-printed sensor to determine the reliability, sensitivity, and dynamic range. The proposed IL-based sensor displayed superior performance with high sensitivity and reliability. The sensor was also investigated for temperature dependence and shelf life. Different applications of the screen-printed sensor were explored such as sensor embedded tire and sensor embedded insole. While the s (open full item for complete abstract)

Committee: Jae-Won Choi PhD (Advisor); Gregory Morscher PhD (Committee Member); Siamak Farhad PhD (Committee Member); Kye-Shin Lee PhD (Committee Member); Thein Kyu PhD (Committee Member) Subjects: Mechanical Engineering