Innovative multifunctional materials are essential to many new sensor applications. Piezoresistive nano-composites make up a promising class of such materials that have the potential to provide a measurable response to strain over a much wider range than typical strain gages. Commercial strain gages are currently dominated by metallic sensors with a useable range of a few percent strain at most. There are, however, many applications that would benefit from a reliable wide-range sensor. These might include the study of explosive behavior, instrumentation of flexible components, motion detection for compliant mechanisms and hinges, human-technology interfaces, and a wide variety of bio-mechanical applications where structural materials may often be approximated as elastomeric. In order to quantify large strains, researchers often use optical methods which are tedious and difficult. This thesis proposes a new material and technique for quantifying large strain (up to 40%) by use of piezoresistive nano-composite strain gages. The nano-composite strain gage material is manufactured by suspending nickel nano-strands within a biocompatible silicone matrix. Study and design iteration on the strain gage material requires an improved understanding of the electrical behavior and conduction path within the material when strained. A percolation model has been suggested for numerical approximations, but has only provided marginal results for lack of data. Critical missing information in the percolation model is the nano-strand cluster size, and how that size changes in response to strain. These data are gathered using a dynamic technique in the scanning electron microscope called voltage contrast. Cluster sizes were found to vary in size by approximately 6% upon being strained to 10%. A feasibility study is also conducted on the nano-composite to show its usability as a strain gage. High Displacement Strain Gages (HDSGs) were manufactured from the nano-composite. HDSGs measured the strain of bovine ligament under prescribed loading conditions. Results demonstrate that HDSGs are an accurate means for measuring ligament strains across a broad spectrum of applied deformations.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-3174 |
| Date | 25 June 2010 |
| Creators | Hyatt, Thomas B. |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | http://lib.byu.edu/about/copyright/ |
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