Matching Items (2)
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- All Subjects: Stretchable Electronics
- Creators: Hildreth, Owen
Description
Gallium-based liquid metals are of interest for a variety of applications including flexible electronics, soft robotics, and biomedical devices. Still, nano- to microscale device fabrication with these materials is challenging because of their strong adhesion to a majority of substrates. This unusual high adhesion is attributed to the formation of a thin oxide shell; however, its role in the adhesion process has not yet been established. In the first part of the thesis, we described a multiscale study aiming at understanding the fundamental mechanisms governing wetting and adhesion of gallium-based liquid metals. In particular, macroscale dynamic contact angle measurements were coupled with Scanning Electron Microscope (SEM) imaging to relate macroscopic drop adhesion to morphology of the liquid metal-surface interface. In addition, room temperature liquid-metal microfluidic devices are also attractive systems for hyperelastic strain sensing. Currently two types of liquid metal-based strain sensors exist for inplane measurements: single-microchannel resistive and two-microchannel capacitive devices. However, with a winding serpentine channel geometry, these sensors typically have a footprint of about a square centimeter, limiting the number of sensors that can be embedded into. In the second part of the thesis, firstly, simulations and an experimental setup consisting of two GaInSn filled tubes submerged within a dielectric liquid bath are used to quantify the effects of the cylindrical electrode geometry including diameter, spacing, and meniscus shape as well as dielectric constant of the insulating liquid and the presence of tubing on the overall system's capacitance. Furthermore, a procedure for fabricating the two-liquid capacitor within a single straight polydiemethylsiloxane channel is developed. Lastly, capacitance and response of this compact device to strain and operational issues arising from complex hydrodynamics near liquid-liquid and liquid-elastomer interfaces are described.
ContributorsLiu, Shanliangzi (Author) / Rykaczewski, Konrad (Thesis advisor) / Alford, Terry (Committee member) / Herrmann, Marcus (Committee member) / Hildreth, Owen (Committee member) / Arizona State University (Publisher)
Created2015
Description
Research on incorporating liquid metal into flexible substrates has resulted in a new avenue for research. Currently, the most promising technique performed was coating a cotton fiber in liquid metal and then using high heat to remove the fiber from the liquid metal without the use of flames or solvents. This is promising in that thin fibers could be coated to create the circuitry, then removed from the liquid metal. The remaining liquid metal could then be encased in a flexible polymer. This then sparked the idea of using a mortar and pestle to manually mix the liquid metal into the elastic substrate, in this case PDMS. Other materials can also be mixed in, such as graphite or alumina to create thermal interface materials (TIMs). These compounds are then poured into molds to cure, then are taken to be tested for thermal conductivity. The results have not yet returned, but this research will continue by changing the ratios of the materials in the TIMs as well as moving forward with encasing the remaining Galistan in elastomer once the fabric was removed through oxidation.
ContributorsKemme, Nicholas Austin (Author) / Rykaczewski, Konrad (Thesis director) / Hildreth, Owen (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05