Importance

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Abstract

Apparatus is disclosed for measuring the electrochemical activity of a liquid, for example, the hydrogen ion activity or pH value of blood. A disposable cartridge includes spaced indicating and reference electrodes which develop electrical properties as a function of the electrochemical activity. The cartridge carries a capsule containing an electrolyte solution. A machine for measuring the electrochemical activity includes a socket in a pivoting door for receiving the cartridge. When the door is pivoted into a closed position, the capsule is automatically crushed thereby covering the electrodes with the solution. The breaking of the capsule triggers an electronic measurement of the resultant electrical properties that develop between the two electrodes. This calibration factor is stored and used to compute the electrochemical characteristics of the sample when it is introduced into the cartridge to cover the indicating electrode. In one embodiment a photocell arrangement emits light which is absorbed by the sample so as to automatically trigger the final measurement when the sample is in contact with the indicating electrode. The cartridge is heated to a predetermined temperature to insure the accuracy of the measurement. Preferably, the socket assembly includes heater pads on opposing printed circuit boards which come into contact with the cartridge when the door is closed. The cartridge has a thermally conductive insert adjacent the tip of the indicating electrode which is contacted by a sensor in the socket to provide signals to a microcomputer which is adapted to control the measurement process. The heater system is selectively disabled by the microcomputer to insure the accuracy of the measurement.

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First Claim