SENSOR SYSTEM

PROBLEM TO BE SOLVED: To provide a compact sensor system capable of performing in a short time, without performing isothermal treatment in a prescribed time, when quantitating enzyme activity in specimen liquid via a plurality of reactions.SOLUTION: A specimen liquid reaction device 1 includes: a reaction chamber 4 connected to a specimen liquid storage chamber 7 through a first channel 8, for storing a specimen substrate to be reacted with a component to be measured in specimen liquid; a fine pump 10 inserted so that the lower end is communicated with the reaction chamber 4; a reaction liquid circulation space 12 connected through a second channel 14 having a larger sectional area than the first channel; and a check valve 17. The device 1 further includes a plane type optical waveguide sensor 21 mounted so as to be positioned in the reaction liquid circulation space 12, and including a sensing film containing at least a film-forming component and a redox dye. and also containing a reaction reagent for generating an oxidative material or a reductive material from a reduction product of the component to be measured and the reaction substrate in either or both of the reaction chamber 4 and the sensing film.