Sensing method

A sensing method for sensing an object in a sample solution based on a frequency change corresponding to a mass of the object adhered to the electrode, using a piezoelectric resonator including a piezoelectric piece with an electrode with an adsorbing layer to capture the object, and oscillating the piezoelectric resonator in contact with a liquid by an oscillator circuit, the sensing method comprising:

• supplying the sample solution to the adsorbing layer;
• subsequently supplying a first liquid to the adsorbing layer, the first liquid including a first sensitizer to bind with the object;
• subsequently discharging the first liquid from the adsorbing layer;
• subsequently supplying a second liquid to the adsorbing layer, the second liquid including a second sensitizer, the second sensitizer reacting to the first sensitizer to generate an insoluble material;
• obtaining a first frequency signal corresponding to an oscillation frequency of the oscillator circuit, the oscillation frequency being obtained by oscillating the piezoelectric resonator after the first liquid is supplied to the adsorbing layer and before the second liquid is supplied to the adsorbing layer;
• and
• obtaining a second frequency signal corresponding to an oscillation frequency of the oscillator circuit, the oscillation frequency being obtained by oscillating the piezoelectric resonator after the second liquid is supplied to the adsorbing layer.