Biosensor, method of forming thin-film electrode, and method and apparatus for quantitative determination

A quantification apparatus for detachably connecting a biosensor and quantifying a substrate included in a sample liquid supplied to the biosensor, said biosensor comprising:

• a first insulating support and a second insulating support;
• a specimen supply path for introducing the sample liquid including the substrate to be quantified, to an electrode part;
• an electrode part comprising at least a working electrode, a counter electrode, and a detecting electrode as an electrode for confirming whether the sample liquid is drawn inside the specimen supply path;
• and
• a reagent layer employed for quantifying the substrate included in the sample liquid;
• where the electrode part, the specimen supply path, and the reagent layer are situated between the first insulating support and the second insulating support,
• the specimen supply path being provided on the electrode part, and the reagent layer being provided on the electrode part in the specimen supply path, respectively, and
• the electrode part being dividedly formed by a first type of slits provided on an electrical conductive layer which is formed on the whole or part of an internal surface of one or both of the first insulating support and the second insulating support;
• where the quantification apparatus comprises:
• a first current/voltage conversion circuit for converting a current from the detecting electrode included in the biosensor into a voltage;
• a second current/voltage conversion circuit for converting a current from the working electrode included in the biosensor into a voltage;
• an A/D conversion circuit for digitally converting the voltage from the first current/voltage conversion circuit and the second current/voltage conversion circuit;
• a first selector switch that switches the connection of the detecting electrode of the biosensor to the first current/voltage conversion circuit or ground;
• and
• a control part for controlling the A/D conversion circuit and the first selector switch;
• where the control part is configured for:
• applying a voltage between the detecting electrode and the counter electrode as well as between the working electrode and the counter electrode in a state where the first selector switch is connected to the first current/voltage conversion circuit;
• detecting an electrical change between the detecting electrode and the working electrode as well as an electrical change between the working electrode and the counter electrode, respectively, occurring when the sample liquid is supplied to the reagent layer provided on the specimen supply path;
• thereafter connecting the first selector switch to ground;
• and
• measuring a current generated by applying a voltage between the working electrode and the counter electrode as well as between the working electrode and the detecting electrode.