Microstructured flexible sensors for wearable technologies

Abstract

As common electronics in our daily life, various sensors have been frequently used in a diversity of applications like pressure sensors for weight scales and temperature sensors for thermometers. However, most traditional sensors are built on rigid substrates, and this restricts the usage of these sensors for many areas requiring flexible devices, such as invasive healthcare monitoring. Thus, there’s a need for developing flexible sensors on flexible and stretchable substrates, especially in emerging applications in internet-of-things. In this thesis, we proposed a new concept, digital microelectromechanical (MEM) sensors based on the insulating-to-conducting transition of devices through mechanical switching, for pressure and strain detection. By adding eco-friendly nanomaterials - cellulose nanocrystals, we greatly improved the response time of our MEM sensors. Furthermore, we optimized our fabrication process to integrate multiple sensors into one device employing polymer microelectromechanical systems. Many practical applications have been demonstrated using our sensors, from hand gesture detection to heart rate monitoring. We also showed that integrated flexible sensors have the potential to control robotic arms and gripping forces in handing physical objects.