Materials and devices for stretchable electronics and electronic skin
- Mechanically compliant electronics enable exciting new technological opportunities, especially in the field that integrates electronics with soft, irregular, and moving objects such as the human body. Wearable, implantable, and prosthetic devices benefit from engineering the mechanics to match that of biology to minimize measurement errors, reduce inflammation, and promote lifelike characteristics, respectively. Chapter 1 of this thesis gives an overview of the current status of mechanically compliant materials and sensors. Chapter 2 describes preliminary efforts toward creating stretchable transistors using polymeric semiconductors. The role of semiconductor mechanics on the stretching behavior of the transistor is investigated, and we found that brittle semiconductors could form microcracks that lead to strain-independent stretching characteristics after an initial preconditioning step. Contact resistance plays a large role in the device performance and the stretching performance; larger contact resistance is typically associated with lower performance, but more constant performance with strain. Chapter 3 describes stretchable transistors composed entirely of carbon nanotubes and elastomers. By combining carbon nanotubes, which have very high mobility, with thermoplastic elastomers, we were able to create devices with exceptional toughness and tear resistance. We investigated the limiting factors for device performance in stretchable devices by varying the semiconducting CNT diameter. We found that at small CNT diameters, the devices are limited by the low charge densities in the channel caused by the use of low-capacitance dielectrics. At large diameters, the devices were limited by low doping levels and contact resistance. In addition to data analysis elements such as transistors, wearable and bio-integrated electronics require sensors such as pressure sensors. Chapter 4 describes a novel type of resistive pressure sensor based on microstructuring conductive polymers to make them elastic. When pressure is applied to a counter-electrode, the contact area increases, decreasing the resistance across the interface. These sensors have excellent sensitivity and minimal temperature dependence. Creating electronics that communicate in the same way as biological organisms could facilitate seamless integration between technology and the human body. Toward this end, we prepared an artificial analogue of biological mechanoreceptors. The system combines flexible circuits with pressure sensors that have been engineered to modulate the frequency of voltage pulses created by the flexible circuits. The artificial mechanoreceptor could communicate pressure information to neurons in vitro, demonstrating the potential of the approach for bio-integrated electronics.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Materials Science and Engineering.
|Statement of responsibility
|Submitted to the Department of Materials Science and Engineering.
|Thesis (Ph.D.)--Stanford University, 2017.
- © 2017 by Alex Chortos
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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