Patent ID: 7850839

Claim:
A method of measuring a quantity of a substrate included in a sample liquid, comprising the steps of: providing a biosensor which includes: an insulating board; an electrode section formed on at least a part of the insulating board, the electrode section including a counter electrode, a measuring electrode, and a detecting electrode: a sample supplying path for supplying the sample liquid to the electrode section; and a reagent layer for reacting with the sample liquid supplied through the sample supplying path, wherein the detecting electrode is disposed most downstream among the counter electrode, the measuring electrode, and the detecting electrode along the sample supplying path from an inlet along a direction of flow of the sample liquid; providing a measuring device which includes: a supporting section for detachably supporting the biosensor; and a connecting terminal and a driving power supply for applying a voltage to the electrode section; inserting the biosensor into the supporting section of the measuring device; applying a voltage with the driving power supply to a first group including the counter electrode and the measuring electrode; and applying a voltage with the driving power supply to a second group including the detecting electrode and one of the measuring electrode and the counter electrode; and determining whether or not the sample liquid is supplied sufficiently for measurement depending on whether or not respective electric currents supplied from the first and second groups exceed respective predetermined thresholds.