Development of Flexible Pressure and Strain Sensors for Electronic Skin Applications

Human intervention can be replaced through development of devices with a broad range of sensory capabilities for various applications from human-robot-interaction to wearable electronics. Similar to the five human senses, sensors interface with their surroundings to stimulate a suitable response or action. The sense of touch which arises in human skin is among the most challenging senses to emulate due to its ultra-high sensitivity. Development of flexible pressure and strain sensing devices with human-like sensory capabilities has thus been the focus of many studies. Some novel challenging issues brought forth in this area are fabrication of flexible pressure sensors with tunable parameters and high sensitivity, development of a comprehensive analytical model capturing their pressure sensing performance, and fabrication of large strain flexible strain sensors with high stretchability and sensitivity and low hysteresis. Therefore, this work attempts to address some of these issues and provide a platform for further optimization and enhancement of flexible pressure and strain sensors. The research focuses on two main sections: i) Flexible pressure sensors, and ii) Large strain flexible strain sensors. For pressure sensing purposes, the change in the contact resistance is utilized as the main sensing mechanism within two structures as a conductive hydrogel and an interlocked microstructured elastomer. The former is constituted from hollow microspheres whereas the latter contains protruding micropyramids. A semi-analytical model is also developed to capture the change in the contact resistance in response to a mechanically applied stress. For strain sensing purposes, flexible and highly stretchable nano/micro fibers are fabricated using an electrospinning technique. The developed fibers possess shape memory properties which contribute to an enhanced recovery of the sensor after undergoing large deformations. Furthermore, using a thermoplastic elastomer, strain sensors with stretchability up to 1000%, high sensitivity and low hysteresis are fabricated using a modified electrospinning technique.Ph.D.2021-10-30 00:00:0