Soft Electronic Materials for Stretchable Circuits & Devices

Stretchable electronics have shown great potential for emerging applications in mechanically deformable displays, soft robotics, wearable computing, bio-integrated devices for human health monitoring, and energy storage and harvesting. Compared to traditional silicon based electrical system, stretchable electronics enables devices to remain functional under mechanical deformation such as twisting, bending, compressing, and stretching. Future progress in stretchable circuits and devices depends on high performance soft and stretchable electronic materials. Efforts in soft and stretchable electronic materials have been largely focused on improving two essential performances, including electrical property (e.g. electrical conductivity, dielectric permittivity) and mechanical property (e.g. stretchability, compliance). My dissertation focuses on developing high performance soft and elastic conductive and high dielectric materials to expand the material selection domain for the development of stretchable electronics.

In this dissertation, a materials architecture of liquid metal (LM) elastomer nanocomposites are designed to enhance the dielectric permittivity without degrading mechanical properties (stretchability and softness) and dielectric breakdown strength significantly for stretchable dielectric materials. I also introduce a phase segregated silver-silicone (PS3) materials architecture that is designed for soft, stretchable, and thermally stable conductor. PS3 composites are enabled with core-shell silver coated PDMS beads and silver flakes embedded in PDMS matrix. In addition to these composites, I also introduce two classes of soft and stretchable multifunctional electronic materials, i.e. a transparent, stretchable conductive film composed of liquid metal traces that are patterned using direct laser writing technology, and is a sediment liquid metal (SLM) elastomer composite for stretchable and wearable triboelectric nanogenerators (TENGs). A series of applications, including dielectric elastomer actuators, dielectric generators, strain sensors, RFID antennas, TENGs, and soft display, are presented to demonstrate these materials.