Calibration and Field Deployment of Low-Cost Fluid Flow-Rate Sensors Using a Wireless Network

Low-cost networked fluid flow velocity sensors are needed for high-density sampling in environmental research and other applications requiring automated fluid flow velocity mapping. The flow sensor in this paper is the "target" type consisting of a flap that deflects in the flow, changing the resistance of a strain gauge. A highly compliant flexible resistor promises to reduce costs by serving as the flow target and by eliminating the signal amplification circuitry needed for conventional strain gauges. However, we show that the individual calibration of these resistive sensors is critical for recovering the stream flow velocity. A wireless network is used for the mass calibration of multiple sensors in a test flume. After individual sensor calibrations are obtained, the same wireless network can be used to collect flow velocity data in the sensor application. A modular connection system enables the user to reconfigure quickly the system's physical layout for calibration or deployment purposes. The results are reported on an outdoor deployment of the flow sensors for logging stream flow data in environmental research.