Method and sensor for detecting a substance in a liquid with surface acoustic wave elements

摘要

A method that enables detecting a substance in a liquid with high accuracy and high sensitivity is provided. A method for detecting substance in liquid includes recording frequency drifts of output frequencies of oscillator circuit outputs of m sensing oscillator circuits 2a to 2m respectively having sensing SAW elements 3a to 3m and frequency drifts of output frequencies of oscillator circuit outputs of n reference oscillator circuits 3a to 3n respectively having reference SAW elements 6a to 6n; determining at least one of the sensing oscillator circuits whose frequency drifts fall within a predetermined range and at least one of the reference oscillator circuits whose frequency drifts fall within the predetermined range to be allowed; selecting at least one of the sensing oscillator circuits from among the allowed sensing oscillator circuits and at least one of the reference oscillator circuits from among the allowed reference oscillator circuits; and comparing an oscillator circuit output of the selected at least one of sensing oscillator circuits with an oscillator circuit output of the selected at least one of reference oscillator circuits to thereby detect a detection target substance.