Nihon Kohden Corporation

Yuko Nagai

Tetsushi Sekiguchi

Michihiro Nakamura

Kohei Ono

Tetsuya Makino

An annul protecting portion having a thickness larger than the thickness of a sensor sensitive portion is provided in such a manner as to surround the sensor sensitive portion , the sensor sensitive portion together with the protecting portion is placed between living tissues, so as to ensure that the gate portion is not subjected to an external pressure by coming into contact with the living tissues. Further, outer peripheries of lead wires on the sensor sensitive portion side are covered with a plasticity material woven into a tubular shape by a metal wire such as a stainless steel wire, and is grounded together with the metallic protecting portion, so as not to be subjected to induction noise. Further, the metal wire is bent to hold the sensor sensitive portion at a suitable angle.

Biological sensor

The conduit tube and the conduit tube to flow the carrier solution to the gas exchanger are provided, and in the conduit tube , the reference pH electrode is provided, and in the conduit tube , the measuring pH electrode is provided, both pH electrodes preferably being chosen of the ISFET type (Ion-Sensitive Field-Effect-Transistor). The gas exchanger is partitioned from the outside by the gas permeable membrane . Initially, the gas exchange section is inserted into the test substance, and next, the carrier solution is flowed at the speed of a degree in which the gas exchange is not conducted in the gas exchanger . The output potential difference &Dgr;V(0) between the reference pH electrode and the measuring pH electrode at this time, is found. Next, the carrier solution is slowly flowed at a predetermined speed, so that the gas exchange is fully conducted in the gas exchanger , the output potential difference &Dgr;V(t) between the reference pH electrode and the measuring pH electrode at time t is found, and the difference &Dgr;&Dgr;V(t) between the &Dgr;V(t) measured at this time and the &Dgr;V(0)obtained at the last time, is obtained. This value corresponds to the correct gas partial pressure change.

Gas sensor and gas sensor system

A biological gas sensor for measuring a carbon dioxide partial pressure in an alimentary canal while excluding the influences of hydrogen sulfide and/or weak acid is disclosed. The gas sensor comprises a sensor which has in the sensitive part thereof a bicarbonate buffer solution held by a gas permeable membrane and detects a carbon dioxide partial pressure based on the hydrogen ion concentration of the bicarbonate buffer solution, a liquid holding part which is formed of a gas permeable tube having in the inside thereof the sensitive part of the sensor, an isotonic solution which is held in the liquid holding part and is isotonic with the bicarbonate buffer solution, and a metallic member (e.g., a coil of copper wire) so that hydrogen sulfide entering the liquid holding part may react with the metal and precipitate.

Biological gas sensor

A gas sensor 1 has a catheter 3 to which a gas sensor body 4 and a signal guide member 5 for guiding a detection signal of the gas sensor body 4 are attached. The other end of the signal guide member 5 is connected to a connector 6. The gas sensor 1 is airtightly received in the reception body in the state where a connection terminal of the connector 6 is exposed to the outside. The reception body 2 is filled with a mixed gas containing a gas to be measured by a predetermined concentration. At the time of calibration, the connection terminal of the connector 6 is connected to a measurement amplifier while the reception body 2 is not opened and calibration is performed, and at the time of measurement, the reception body 2 is opened and the gas sensor 1 is taken out to perform ordinary measurement.

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Tokyo, Japan

Yuko Nagai