Electrochemical sensor and method for manufacturing electrochemical sensor

An electrochemical sensor, comprising:

• a working electrode;
• a counter electrode;
• a wiring connected to the working electrode;
• and
• a base material supporting the working electrode, the counter electrode, and the wiring,
• wherein the working electrode is a chip-shaped electrode comprising (i) a diamond film that causes a redox reaction on its surface when a predetermined voltage is applied in a state where a test sample exists between the working electrode and the counter electrode, and (ii) a support that comprises a conductive material composed of a silicon alone or a silicon compound and supports the diamond film on a first surface of the support,
• the support has an insulation film consisting of silicon oxide or silicon nitride on an entire side surface of the support and does not have the insulation film on the first surface that supports the diamond film so that the diamond film is in direct contact with the first surface of the support,
• the diamond film does not have the insulation film on an entire top surface and an entire side surface,
• the working electrode and the wiring are electrically connected via a conductive adhesive agent,
• the working electrode is mounted on the base material via the conductive adhesive agent, with the support positioned on the base material,
• the conductive adhesive agent and the wiring are covered with an insulation material in such a manner that they are not exposed, and
• at least a part of the insulation film on the side surface of the support of the working electrode is exposed without covering the insulation material.