A measurement system for the blood flow in peripheral territory

The aim of this study was to acquire non-invasively and to analyze plethysmographic waves, by measuring the electrical impedance of a peripheral segment. For measurements we built a device that is designed as an injection module with a microcontroller which generates a sinusoidal pulse with adjustable frequency (10-200 kHz) and adjustable intensity. In output, the device delivers an analoge signal representing the variation of the impedance of the explored section. Disposable electrodes were used for the injection of the sinusoidal pulse and the collection of the bioimpedance signal. The acquisition of the bioimpedance signal on PC was made easier by the use of a National Instrument data acquisition device, the NI USB 6009. The bioimpedance signal processing, the user interface and the display were managed by MATLAB. The results obtained from of measurements fell within the limits of values found in the literature.