| 摘要 |
The invention relates to a simple and reliable sensor for measuring the value of an electrical property of a medium such as the complex impedance, conductivity, di-electric constant, or ion concentration of a species of interest. The sensing element comprises a bifilar coil in which only one end of each wire is connected to a measurement circuit and the opposite ends are free or unterminated. When the circuit is excited or driven at a particular frequency, this arrangement is lossy and the output signal or response is sensitive to the di-electric properties of the medium or fluid surrounding the sensor. The sensor thus has broad application in situations where it is desirable to detect the amount of, and/or changes in, the ion concentration level of a medium. Applications comprise measuring the salinity and water level in evaporative coolers, and the concentration of sodium metabisulphite in tanks holding seafood. |
