LIQUID SENSOR

Abstract

A liquid sensor is described that can achieve a relatively high detection sensitivity for foreign material in a liquid. The liquid sensor detects the foreign material content in a liquid by immersing at least a portion of it into the liquid. The liquid sensor comprises a first substrate and a second substrate, each with a first electrode and a second electrode. The first and second substrates each also have a first detection circuit. The first detection circuit detects the capacitance of a capacitor formed between the first and second electrodes. The foreign material has a greater influence on the capacitance detected by the first substrate than on the capacitance detected by the second substrate. The liquid sensor also includes a second detection circuit.The second detection circuit detects the amount of foreign material based on the capacitance detected by the first substrate and the capacitance detected by the second substrate.

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