High Accuracy and Simultaneous Scanning AC Measurement Approach for Two-Dimensional Resistive Sensor Arrays

Zero potential circuit (ZPC) is widely implemented for two-dimensional resistive sensor array/matrix measurement to eliminate the crosstalk effect caused by the additional current paths through the un-targeted sensors. However, the measurement accuracy of the ZPC method is strongly influenced by its applied multiplexer switch-on resistors and operational amplifier DC offset voltage. This paper proposes to supply simultaneously each row of the sensor matrix with an AC voltage at a row-specific frequency, so that the responses of sensors in one column can be isolated from each other based on a frequency spectrum analysis and all sensors can be therefore scanned simultaneously. Comparing to the original ZPC method, this new approach does not need the un-targeted sensors to be short-circuited, as well as the multiplexer can be omitted. The resistance value of each sensor is calculated by evaluating its column output signal at the frequency of its corresponding row excitation AC voltage source. The DC offset voltage of the operational amplifier does not influence the measurement anymore because of the AC measurement principle.