AVS 59th Annual International Symposium and Exhibition
    Thin Film Tuesday Sessions
       Session TF2-TuA

Paper TF2-TuA7
Conductivity and Mechanical Stretching of Conductive ALD Coatings on Nonwoven Fiber Mats

Tuesday, October 30, 2012, 4:00 pm, Room 11

Session: ALD for Hybrid Films and Bioapplications
Presenter: W.J. Sweet, North Carolina State University
Authors: W.J. Sweet, North Carolina State University
C.J. Oldham, North Carolina State University
G.N. Parsons, North Carolina State University
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Advanced sensing, responsive and protective electronic systems integrated with fibers and flexible textile media may lead to new solutions for functional device deployment and integration. A challenging aspect of conductive coatings on fibers is the observation that most good conductors, including doped metal oxides or metallic films, are not readily flexible when coated in thin film form onto polymer fibers. For this work, we use atomic layer deposition (ALD) to produce conformal coatings of conductive ZnO, Al:ZnO and others on complex nonwoven polypropylene and nylon fibers. We measured conductivity of the as-formed coated fibers as a function of deposition temperature and other process parameters. We also measured the mechanical response of the coated and uncoated fiber mats, including measuring the change in conductivity upon fiber mat stretching. We find that in all materials measured to date, the conductivity of the fiber mat decreases with increasing applied tensile stress. For example, for Al-doped ZnO on nylon deposited at 115°C, we obtained fiber mats with conductivity of 33 S/cm, and after a 10% strain, the conductivity drops to ~3.3 S/cm. Generally, the largest conductivity decrease occurs for the materials that are most conductive to start. However, results indicate a correlation between some process parameters, such as deposition temperature, and conductivity resiliency, showing possible directions to attain highly flexible and reliable conductive material integration. In this presentation we will summarize our results regarding mechanical resiliency and conductivity and identify key parameters needed to achieve stretchable fibers that are also highly conductive.