Olympus Optical Company, Ltd.

Noriaki Ono

Takashi Kamiyama

Seiichi Hosoda

Kosaku Tsuboshima

Kiyozo Koshiishi

Yoshimi Kato

Satsuki Kohara

A chemical sensing element suitable for measurement of the activity or the concentration of a specific ion contained in an electrolyte is provided with an optically opaque membrane between a gate insulating membrane and an ion sensing membrane of a field-effect type transistor. Since the opaque membrane is provided, extraneous light impinging on a gate is blocked by the opaque membrane, whereby an erroneous potential due to extraneous light is prevented. Accordingly, the accurate measurement of the activity or the concentration of a specific ion contained in an electrolyte may be achieved even in intense ambient light.

Chemically sensitive element

A measuring electrode device comprises a pH electrode arranged within an outer casing and having a pH sensitive member in contact with an electrolyte housed in the outer casing. The electrolyte reacts with a predetermined gas in a liquid to be inspected and varies its pH. The pH sensitive member includes a semiconductor substrate and a pH sensitive membrane formed on the substrate and in contact with the electrolyte. The pH sensitive membrane is formed of at least one element selected from the group consisting of silicon nitride, aluminum oxide and tantalum pentoxide. A potential difference is produced between the pH sensitive membrane and the electrolyte in accordance with the variation of the pH of the electrolyte. Thus, a potential difference is produced between the pH electrode and a reference electrode according to the variation of the pH of the electrolyte.

Measuring electrode device

An ion selective electrode having a silicon wafer substrate secured to one end of a tube made of insulating material by an adhesive agent and an ion sensitive film applied on the outer surface of silicon wafer substrate is disclosed. In order to prevent a portion of a side edge of silicon wafer substrate from being exposed to a sample liquid to be measured, the side edge of silicon wafer substrate is tapered and the ion sensitive film is applied on the tapered side edge as well as on the outer surface of silicon wafer substrate. The tapered side edge may be simply formed by effecting an anisotropic etching for a silicon wafer.

Ion selective electrode

A selective ion sensitive electrode is so constructed that an ion exchanger sensitive to a specific ion is formed on a metal electrode, an electric conductive resin electrode or a chlorinated metal electrode to which a signal wire is connected so as to maintain a stable electric connection between the signal wire and the ion exchanger over a long period of time. A layer of a silane coupling agent is used between the electrode member and ion exchanger.

Selective ion sensitive electrode and method of making it

In measurement of signals containing noise at a known frequency, a method to eliminate noise at a known frequency of T so adapted as to obtain correct value of the signal free from noise by repeating measurements of signal levels at time interval of T/2 and averaging the values obtained by said measurements.

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Akishima, Japan

Noriaki Ono