| 摘要 |
PURPOSE:To make it possible to perform rapid and accurate measurement, by amplifying the reaction current flowing through the reaction cell of a measuring device utilizing an immobilized enzyme membrane by an amplifying circuit having an amplifying ratio proportional to the resistance value of a thermistor and compensating the temp. characteristics of the reaction current by that of the thermistor. CONSTITUTION:An immobilized enzyme membrane is provided in a reaction cell P and, for example, when specimen blood is injected in a cell P, sugar in blood is decomposed by the enzyme in the immobilized enzyme membrane and the resistance value Rs or reaction current (i) between electrodes Pp, Pn changes. Next, an operational amplifier OP1 forms a polarity reversal type proportional amplifier (reversal amplifier) 2 for magnifying the ratio of a resistance value Rs and a resistance value R1 and a reversal amplifier 21 is further formed of an operational amplifier OP2, a thermistor RT1 and a resistor R2. The output voltage V2 of the amplifier 21 is compensated by the temp. characteristics of the thermistor RT1 to obtain voltage based on the current (i) wherein a voltage value coming to a base when a blood sugar level is through an automatic zero circuit 3 and this voltage is read in CPU6 through an amplifier 4 and an A/D converter 5. |
