Potentiometric biosensor and detection method

A method for testing the urea concentration in a sample, comprising the following steps:

• (1) providing an open-circuit potentiometric biosensor;
• (2) inserting the open-circuit potentiometric biosensor into a test instrument;
• (3) adding the sample to the open-circuit potentiometric biosensor, and allowing the sample to chemically react with the first reaction reagent and the second reaction reagent;
• and
• (4) testing the potential difference between the first electrode and the second electrode by means of the test instrument using an open-circuit potentiometric method, and determining the urea concentration in the sample based on the potential difference measured in the open-circuit potentiometric method,
• wherein
• the open-circuit potentiometric biosensor comprises a sample addition end, an electrical connection end, an insulating substrate, an electrode system comprising a reference electrode and an indication electrode, a conductive layer, a reaction region forming layer, a channel forming layer and an upper cover layer;
• the conductive layer is disposed on the insulating substrate, and comprises a first contact and a second contact that are located at the electrical connection end, an indication electrode and a reference electrode that are located at the sample addition end, a first conductive trace for connecting the reference electrode with the first contact, and a second conductive trace for connecting the indication electrode with the second contact;
• the reaction region forming layer covers the electrode system and is provided with a first reaction hole and a second reaction hole that are spaced apart, the first reaction hole exposes at least a part of the reference electrode and forms a first reaction region on the reference electrode, and the second reaction hole exposes at least a part of the indication electrode and forms a second reaction region on the indication electrode;
• the channel forming layer is disposed on the reaction region forming layer, provided with an opening in the sample addition end, and the opening simultaneously exposes at least a part of the first reaction region and at least a part of the second reaction region;
• the upper cover layer is disposed on the channel forming layer and provided with a vent, the upper cover layer forms a sample channel together with the opening, the reaction region forming layer and the insulating substrate, the vent is located above the sample channel, a sample addition port is provided in the sample addition end, and a sample enters the sample channel through the sample addition port;
• and
• a first reaction reagent is located on the first reaction region and contains an electron mediator but does not contain urease, and a second reaction reagent is located on the second reaction region and contains urease but does not contain an electron mediator.