Conductive liquid property measurement using multiple charge transfer times

摘要

Systems and methods for making repeatable measurements of the dielectric constant and conductivity of a material, such as a liquid. In one example, a material property measurement system includes a measurement cell, a voltage measurement circuit, a capacitor, and a switch. The measurement cell is made of at least two conducting electrodes with liquid between the conducting electrodes. The switch is in a current path between the capacitor and the measurement cell. The capacitor is charged and then the switch is closed for a first time period and a first voltage measurement on the capacitor is performed. The capacitor is charged again and the switch is closed for a second time period and a second voltage measurement on the capacitor is performed. The two voltage measurements are used in a calculation to calculate a value related to capacitance between the at least two conducting electrodes of the measurement cell.

主权项

1. A liquid property measurement system comprising:
a measurement cell having at least two conducting electrodes configured to receive a liquid between the at least two conducting electrodes; a capacitor; a voltage measurement circuit configured to determine a voltage on the capacitor; a first switch coupled to the capacitor and in a current path between the capacitor and a voltage source; and a second switch coupled to the capacitor and in a current path between the capacitor and the measurement cell, wherein
the first switch is initially open,the first switch is then closed to initially charge the capacitor and then opened, and a voltage on the capacitor is determined for an initial voltage measurement,after the first switch is opened, the second switch is closed for a first time period and then the voltage on the capacitor is determined for a first voltage measurement,the first switch is then closed to charge the capacitor again and then opened,after the first switch is opened, the second switch is closed for a second time period and then the voltage on the capacitor is determined for a second voltage measurement, andusing the initial voltage measurement, the first voltage measurement, and the second voltage measurement, a value is calculated related to the capacitance between the at least two conducting electrodes of the measurement cell.