Design of a microcomputer-based densitometer system: application to serum protein electrophoresis

We describe how a microcomputer (Apple II Plus) can be interfaced with a commercial densitometer to provide control functions, do automated data processing, and print final reports. The amplified densitometer photodetector signal is digitized, stored, and plotted on the cathode-ray tube to provide a real-time graphical display of data acquisition. The software was designed to identify automatically the five main serum protein fractions and to compute final results. Algorithms were designed to provide medically relevant comments for most of the common abnormal protein patterns, and the comments section was designed so that it could be modified to use specific comments composed by the user. A final report, printed in duplicate, contains information such as the patient's name, identifying numbers, numerical results, normal values, medically relevant comments, and a digitized high-resolution plot of the electrophoretic pattern. The densitometer was one that already had been in use for several years; the microcomputer system, software, and interfaces cost less than $2200.