Microprocessor control of an oxygen electrode system

A technique is described for acquisition and analysis of measurements made with a Clark oxygen electrode. An RCA 1802 microprocessor (ELF) system was modified to provide automatic control with an increase in accuracy. Cost is nominal and installation is straightforward. In our application, we continuously monitored the oxygen content in cultures of respiring algae. The linear changes in oxygen concentration with time were analyzed by a least squares fit program to give the slope representing rate of respiration. This program continually processes the data and retains only the essential information from the least squares program, thereby reducing data storages drastically. The system is initiated with one start key and automatically stores and computes the input data. The program may be terminated manually at any time-usually when the standard error of the mean is less than one percent of the slope value. An eight-digit readout displays the values for the slope, standard error, standard deviation, and correlation coefficient.