DETECTION OF SAMPLE FOR STARTING TIMING OF ELECTROCHEMICAL MEASUREMENT

摘要

PROBLEM TO BE SOLVED: To calculate the concn. of an object to be detected by monitoring the potential difference between electrodes across which a constant current source is connected and determining a sample detecting time at a time when the potential difference becomes a threshold value or less and applying constant voltage to sample to measure electrical response of a constant time. SOLUTION: A weak constant current source is connected across the electrodes of a strip for electrochemical diagnosis to monitor the potential difference between the electrodes. A dry gap is provided between the electrodes and a negligible current flows across the electrodes at an initial stage. When a sample is applied to the strip to fill the gap, measuring voltage drops suddenly and a test is started at this point of time. When the application of the sample is recognized, an apparatus is changed over from a constant current mode to a constant voltage mode and, in the constant voltage mode, a current or charge is measured as a function of time and the calculation of the concn. of an object to be detected becomes possible. By this method, the error introduced into signal responce by a timing start circuit is minimized and a detection restricting value can be lowered.