Ultrasonic Flexural-Plate-Wave Sensor for Detecting the Concentration of Settling<i>E.</i><i>c</i><i>oli</i>W3110 Cells

The flexural-plate-wave (FPW) sensor, a type of ultrasonic sensor, can detect changes in E. coli W3110 concentration in solution as the cells settle onto the sensor under the influence of gravity. A model of the sensor's response to cell settling has been developed and is in good agreement with the experimental data. The FPW technique improves on conventional methods for determining cell concentrations; this technique allows for on-line data collection, is nondestructive, and requires only small sample volumes. The FPW sensor has applications as a device to measure cell concentrations and growth rates in industrial fermentors, biofilms, and wastewater treatment facilities.