A multichannel telemetry system for monitoring physiological information from the human gait: preliminary results

Because gait analysis is a useful tool in the evaluation of rehabilitation treatment, it is necessary to monitor patients´ physiological signals without limiting their movements. In this paper, we describe a biotelemetry system for real time multichannel monitoring of two channels surface electromyography (SEMG), an electrocardiography (ECG) derivation and eight digital signals coming from footswitches to determine the stance and swing gait periods. The system is aimed at being used during electrically assisted walking. The signals picked up by surface electrodes are amplified, filtered and frequency limited in each channel. A transmission block is formed by a microcontrolled system which processes, codes and sends the signals to a radio frequency (RF) transceiver. This device transmits the signals multiplexed in time to another transceiver which receives the signals and transfers them to a second microcontrolled system. The latter decodes and sends the signals through a bidirectional parallel port to a computer where they are visualized and stored. Simulated signals could be observed in real time on the computer screen. The system fulfilled design specifications. We plan to evaluate it in humans and at bigger distances.