Abstract: The circuitry forms part of testing apparatus for measuring the concentration of ions in fluids, primarily body fluids, including the measurement of chlorides, ionized calcium, sodium and potassium as well as other ions. A small sample fluid is subjected to a controlled mechanical oscillation to thoroughly expose a true representative sample to the electrode for measurement. The apparatus has a digital readout display and two associated switches for calibrating the circuitry with high and low standard fluids. The low standard circuit is calibrated with the low standard sample to establish offset correction while the high standard circuit is calibrated with the high standard sample to establish gain correction. After the instrument has been adjusted for proper low and high standard values, for a particular electrode, the offset correction and gain correction parameters are established so that electrode input values cause proper concentrations to be displayed.

Abstract: The testing apparatus is for measurement of ions in body fluids. The apparatus has a plurality of sample cups for containing fluids to be tested, a movable door for controlling access to the sample cups, and a plurality of measuring electrodes for immersion into the fluid to be tested. There is a hand operated device for moving the electrodes and the cups with respect to each other to alternately put the electrodes in a first position permitting access to the cups and in a second position in which the electrodes are immersed in the fluids to be tested contained in the cups. Means for mounting the cups in the testing apparatus are engaged with means for oscillating the cups independently of the electrodes. The oscillation fully exposes the electrodes to a representative sampling of the fluids within the cups and thus enhances the accuracy of the test being performed.

Abstract: The testing apparatus is for measurement of ions in body fluids. The apparatus has a plurality of sample cups for containing fluids to be tested, a movable door for controlling access to the sample cups, and a plurality of measuring electrodes for immersion into the fluid to be tested. There is a hand operated device for moving the electrodes and the cups with respect to each other to alternately put the electrodes in a first position permitting access to the cups and in a second position in which the electrodes are immersed in the fluids to be tested contained in the cups. Means for mounting the cups in the testing apparatus are engaged with means for oscillating the cups independently of the electrodes. The oscillation fully exposes the electrodes to a representative sampling of the fluids within the cups and thus enhances the accuracy of the test being performed.

Abstract: An electrochemical combination electrode assembly particularly adapted for measuring the pH of body portions of a living subject, such as skin, hair, and the like, and which can be operated in any vertical, inclined or horizontal orientation. The assembly comprises a pH-indicating glass electrode supported within a tubular plastic container and includes a generally flat, pH-sensitive structure at a sensing end of the assembly. Conventional indicating and reference half-cell electrodes are supported in separate reservoirs of the assembly containing internal and reference electrolytes, respectively. The upper ends of the reservoirs are sealed by elastomeric plugs which compensate for differing coefficients of expansion within the assembly and coact with the electrolytes to prevent formation and migration of air bubbles to the sensing end of the assembly.