A new sensor for monitoring the continuous operation of exhaust fans in confined animal feeding operations (CAFOs) was developed and tested. The sensor relies on integrated Micro Electro Mechanical Systems (iMEMS) technology to accurately and reliably detect vibration on the external hood of agricultural fans, caused by the rotation of the fan blade. When coupled with a sensor to measure pressure drop across the fan and an appropriate fan curve, the vibration sensor can enable real-time fan specific collection of emission data from animal housing structures.

The sensor integrated an iMEMS accelerometer along with various signal conditioning components to convert the cyclic acceleration signal into a filtered TTL signal appropriate for a wide variety of digital input data acquisition equipment. The overall current draw of the sensor was only 0.9 milliamps, which allowed multiple devices to operate from a single power bus. Laboratory and field testing have shown that the sensor is very accurate in determining the on/off state of exhaust fans. Sensor installation takes only a few minutes and requires only a single hole placed in the existing fan hood. Furthermore, by encapsulating the sensor in a potting compound, all critical electronic components were sealed from the corrosive effects of moisture and gasses common to CAFOs.