Strategies in Stretchable Electronics: Developing Bi-facial, Multi-layer, and Three-dimensional Configurations for Implantable Bio-electronics and Displays Applications

Abstract

Stretchable electronics are attracting significant attention owing to their remarkable potential for extending novel characteristics to a diverse range of applications including displays, soft robots, wearable devices, and even implantable devices. However, conventional single-layered stretchable electronics have inevitable limitations in minimized and integrated constructions, impeding advancement of multi-functionality in stretchable electronics. Through the development of multiple layered structures in stretchable electronics, it is becoming possible to overcome limitations and realize multi-functionality, minimized designs, and even novel functionalities such as three-dimensional stretchable electronics. The primary focus of this dissertation was to develop design strategies for achieving multi-functional and minimized stretchable electronics with multiple layers. This dissertation proposes three types of minimized and optimized stretchable electronics utilizing rigid thin film. It introduces structure-based stretchable electronics for integrating various rigid components, ensuring both electrical and mechanical stabilities. First, using a sustainably-powered multifunctional flexible feedback implant by bi-facial design and Si photovoltaics, a strategy is developed for the design of self-powering bi-facial stretchable electronics demonstrating efficient multi-functionality under soft skin. Second, using multilayer stretchable electronics with a design enabling compact lateral form, a strategy is developed for low-strain design of multilayer stretchable electronics demonstrating minimized, implantable bio-electronics and stretchable displays. Last, using 3D stretchable electronics formed by tilted stretchable interconnector design for omnidirectional deformations, a strategy is developed for three-dimensional design of 2D stretchable thin film circuits, and a fully stretchable 3D cube display is demonstrated. Advanced stretchable electronics that can overcome conventional single-layer design and 2D structure can be useful, substituting for rigid traditional electronics with efficient applications and stable functionalities. The results presented in this dissertation should be useful for a wide range of applications that require stable, high-density, and multi-functional electronics.