Patent ID: 6222366
Filing Date: 2001-04-24
Classification: G01G,G01N

Abstract:
A process for measuring concentration of analyte in a fluid comprising:placing a quartz crystal microbalance sensor device in the fluid containing the analyte, the sensor device having a resonant frequency based on the concentration of the analyte in the fluid and having an initial resonant frequency before the sensor device is exposed to the analyte;providing a quartz crystal microbalance reference device, the reference device having a resonant frequency in predetermined relation to the initial resonant frequency of the sensor device;summing the resonant frequencies of the sensor device and the reference device to provide a difference signal frequency representative of the difference between the resonant frequencies of the sensor device and the reference device;counting a predetermined number of cycles of the difference signal frequency to identify a sample time period; andcounting cycles of a clock signal frequency during the sample time period to derive a count representative of the difference signal frequency.