Abstract: The present invention provides a method for measuring concentrations of the first and second substrates in a sample liquid by using a biosensor. The biosensor has an electrically insulating substrate, an electrode system, and a reaction layer including a first enzyme, a second enzyme and an electron acceptor. The method includes the steps of measuring a response current value I.sub.1 of a predetermined period of time T.sub.1 after supplying the sample liquid including the first and second substrates to the biosensor; measuring a response current value I.sub.2 of a predetermined period of time T.sub.2 after the supply of the sample liquid; obtaining the concentration C.sub.1 of the first substrate corresponding to the current value I.sub.1 based on the previously determined relationship between the concentration of the first substrate and the response current value of the predetermined period of time T.sub.1 after the supply; obtaining a response current value I.sub.1 ' corresponding to the concentration C.

Abstract: The subject invention provides a simple sensor and an easy to handle biosensor measuring apparatus for the purpose of making measurements easily, rapidly and with high accuracy for specific components within a biological specimen such as blood.The biosensor of the subject invention is provided with a protrusion or a depression in a portion of a base having at least a measurement electrode and an opposing electrode. Also, the biosensor measuring apparatus is so configurated to have a mating means in the main body of the measuring apparatus freely supporting this biosensor to contact the said sensor's protrusion or depression, and further having the activating switch of the driving power supply located in this mating means.By means of these, it is possible to prevent wasteful measuring operations, as noted in the prior art biosensors, such as inserting the sensor backwards and making measurements with the sensor inserted backwards.

Abstract: A sensor 13 is inserted into a connector 14. A constant voltage required to obtain a response current is applied across the connector 14 by a voltage applying source 15 at timings required. A response current of the sensor 13 inserted into the connector 14 is converted into a voltage by a current-to-voltage converter 16, and the amount thereof is determined by a microcomputer, the analysis results being displayed onto a display unit.

Abstract: The present invention provides a biosensor comprising an electrical insulating substrate, a main electrode system formed on the substrate and having a working electrode and a counter electrode, a reaction layer provided in contact with or in the vicinity of the main electrode system and containing an oxidoreductase, and a sub electrode system as a reference provided with an interval from the main electrode system and having a working electrode and a counter electrode.

Abstract: The present invention relates to a process of preparation of a biosensor comprising forming an electrode system mainly containing carbon on an insulating base plate, treating the surface of electrode system with an organic solvent, and then arranging a reaction layer on the electrode system to give a unified element. The reaction layer contains an enzyme, electron acceptor and a hydrophilic polymer. Treatment with the organic solvent improves adhesion of the reaction layer to the electrode system. The electrode system contains a working electrode and a counter electrode. The electrode system is formed from a carbon paste containing a resin binder. Treatment is preferably carried out by wiping the surface of the electrodes with a material impregnated by the organic solvent.

Abstract: The biosensor of the present invention quantifies a substrate contained in a sample liquid by reducing electron acceptors using electron generated in a reaction of the substrate to enzyme and then by measuring the reduced amount of the electron acceptors electrochemically. The biosensor has an electrical insulating substrate, an electrode system including at least a working electrode and a counter electrode, a reaction layer including the enzyme provided on the electrode system and a hydrogen ion concentration control layer, and the reaction layer is in contact with the electrode system. According to the present invention, the hydrogen ion concentration in the sample liquid can be made most appropriate in accordance with the type of the enzyme contained in the reaction layer, without the adjustment of the hydrogen ion concentration in the sample liquid beforehand. Thus, the specific substrate contained in the sample liquid can be easily quantified with accuracy and speed.