Designed to Fail: Flexible, Anisotropic Silver Nanorod Sheets for Low-Cost Wireless Activity Monitoring

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• 作者：Layne Bradley ; George Larsen ; Yiping Zhao
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：July 14, 2016
• 年：2016
• 卷：120
• 期：27
• 页码：14969-14976
• 全文大小：513K
• 年卷期：0
• ISSN：1932-7455

文摘

We describe the fabrication and properties of flexible, anisotropic silver nanorod sheets and investigate their potential to function as a sensor. Aligned and tilted silver nanorod (AgNR) arrays are incorporated into polydimethylsiloxane (PDMS) to form flexible conductive sheets. The electrical properties of these sheets are investigated and show large anisotropies, which are related to the alignment direction of the nanorods. Notably, the films show the greatest electrical resistance in the direction perpendicular to the nanorod alignment, and when strain is applied along this direction, the resistance increases monotonically with increasing loading/unloading cycles. In comparison, the resistance along the nanorod alignment direction remains constant over many strain cycles and therefore can serve as an internal reference or as a stable strain gauge. These changes in resistivity are attributed to changes in the internanorod connectivity and can be modeled using an effective medium approximation for anisotropic percolation. Stable piezoresistivity (in one orientation) and surface-enhanced Raman scattering activity of the AgNR sheets make them attractive for flexible electronics applications such as electronic skin or as monitors for human–machine interactions. However, the ability to encode a surface’s dynamic history into material properties through resistance changes is a considerable simplification over other systems and can enable wireless activity monitoring where cost or demanding environments prevent more complicated devices from being implemented.