Date of Award
Chemistry and Biochemistry
Tricia B Carmichael
Composites, Polydimethylsiloxane (PDMS), Silica nanoparticles, Stretchable electronics, Thin gold films, Wearable electronics
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Stretchable conductors play a fundamental role in wearable electronics as device electrodes and interconnects. Polydimethylsiloxane (PDMS) is conventionally used as the platform for stretchable conductors which are fabricated by depositing a thin layer of gold metal onto the surface. These gold films fail electrically under minimal strains (15-20% linear elongation) due to uncontrolled crack propagation through the metal film. Adding a rough microstructured polymer layer onto the PDMS surface preserves electrical conductivity in metal films to higher elongations of 60% due to the numerous sites for strain localization. However, such heterogeneous layered systems are vulnerable to delamination, leading to device failure. In this thesis, we fabricate a composite layer by combining silane modified silica nanoparticles together with PDMS prepolymer on top of an elastomeric substrate to enable the fabrication of stretchable gold films.
Chapter 2 describes the fabrication and deposition of this composite layer onto an elastomeric substrate for robust interlayer adhesion for the fabrication of stretchable gold films. Changing the loading and dispersity of the particles in the composite layer enables gold films to stretch to 50 - 70% elongations. There is a very linear change in resistance with elongation that is unique to each particle loading creating a tunable system with the opportunity for different strain sensor applications.
Chapter 3 expands on the work in Chapter 2 by examining the effect of dramatically changing the particle size, from 12 nm (Chapter 2) to 300 nm on the organization and structure of the composite surface and the influence on the retention of conductivity with stretching of overlying gold films. By increasing the size of the particles, they associated less with one another and with the polymer resulting in films with less topography and higher resistances upon elongation.
Ives, Brittany, "Composites of Poly(dimethylsiloxane) and Silica Nanoparticles as an Approach to Manipulating the Conductivity of Stretchable Gold Films" (2019). Electronic Theses and Dissertations. 7758.