Patent ID: 7982451

Claim:
A sensing instrument which uses a sensing sensor including a piezoelectric resonator changing in natural frequency by the adsorption of a sample and which senses the adsorption of the sample based on the change in the natural frequency of the piezoelectric resonator, the instrument comprising: an oscillator circuit unit to which the sensing sensor is connected and which includes an oscillator circuit for oscillating the piezoelectric resonator of the sensing sensor; an instrument main body attachably/detachably connected to the oscillator circuit unit and including a measuring unit measuring a signal regarding a frequency of an oscillation output of the oscillator circuit; a frequency sorting circuit provided in the instrument main body, and including a plurality of channels and a plurality of band-pass filters, the channels branching off from a frequency signal line extending from the oscillator circuit unit, and the band-pass filters being provided in the channels respectively and having pass characteristics corresponding to the oscillation frequencies of the oscillator circuits respectively; a switching unit connecting a selected channel among the plural channels to the measuring unit; a plurality of level detecting circuits detecting signal levels at output sides of the plural band-pass filters respectively; and a control unit comparing level detection values, which are detected by the plural level detecting circuits respectively, with a threshold value, controlling the switching unit so as to connect, to the measuring unit, a channel for which the level detection value equal to or higher than the threshold value is output, and controlling the measuring unit according to a frequency of a frequency signal corresponding to the connected channel.