Two miniature monitors for long-term ambulatory studies

Abstract

Two very low-power monitors are described. One typically limb-worn to record the level of physical activity of a person; the other, used with surface electrodes, to record three parameters of an EMG signal. The monitoring period can extend to days with a very accurate 'time of event' log. A novel method has been devised to double the resolution of the data gathered. A PC is used to store and process the collected data, which can be displayed or printed as one-, or four-channel, time-related histogram. The gathered data can also be analysed for trends and other statistical analysis. The hardware is relatively simple and made from low-cost components. Neither monitor uses a microprocessor for data gathering. The system is very easy to use requiring minimal operator training. Where 'no-frills' ambulatory monitoring is called for, the systems presented would compare very favourably with other commercially available monitors, either on cost, complexity of setting up, or on weight.