(page created: 11/01/2001; last modified: 11/30/2001 )
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Dean Neikirk (Dept. of Electrical and Computer Engineering) and Sharon Wood (Dept. of Civil Engineering)
Identifying material degradation (e.g., corrosion of metals, or weld failures due to an extreme event) in large civil structures (e.g., a bridge or building) before actual failure is a critical problem. When remote sensing (e.g., electromagnetic fields) is used to examine materials in such a structure many effects can produce identical response, leading to low confidence in the relation between measurands and actual material state. To avoid this, point sensors with limited cross-sensitivity can be used so the relation between measurement and state are nearly unique. For point sensors buried in a civil structure a very large number might be required; hence the power used by the sensor and the method of interrogation are critical constraints. Combined with constraints in construction, wireless power coupling and data transmission are required for embedded sensors that must function for many years (since the lifetime of a civil structure is measured in decades). We are investigating power and data coupling using an ac transceiver inductively coupled to the sensor system. The induced current operates the transducer, which then produces a response broadcast back to the transceiver.