SENSOR INCLUDING TWO ENTWINED SPIRAL ELECTRODES

摘要

An electrical sensor for resistance and capacitance measurements which includes two entwined spiral electrode tracks and an electrical circuit for testing the integrity and electrical continuity of the electrode tracks are disclosed. The entwined spiral electrode tracks maximize the effective surface area of the sensor while generating a uniform electric field across the surface of the sensor. The terminal leads at the ends of each electrode track are connected to an I/O pin of the microprocessor. In testing the sensor, the microprocessor applies a reference voltage signal through one of the electrode tracks through one of the I/O pins. If the microprocessor fails to read the reference voltage signal at the oppositely connected I/O pins on that electrode track, the microprocessor indicates a continuity failure in that track. If the microprocessor reads a voltage signal at one of the I/O pins connected to the other electrode track, the microprocessor indicates a short failure between the electrode tracks.