Method and system of acquisition of a signal representative of the diameter of a blood vessel

A system for acquiring a signal representative of a diameter of a blood vessel comprising:

• an ultrasonic sensor;
• a photoplethysmography sensor;
• and
• a data processing device configured to, during a calibration phase:
• 1) determining a reference signal representative of the evolution of the diameter of the blood vessel during a calibration period, by means of the ultrasonic sensor;
• 2) acquiring an optical signal representative of the evolution of the blood vessel during the calibration period, by means of the photoplethysmography sensor;
• 3) determining, from the optical signal measured in the step 2) and the reference signal determined in the step 1), a mathematical model adapted to generate, from the only optical signal measured in the step 2), an estimated signal representative of the evolution of the diameter of the blood vessel during the calibration period,
• the data processing device being further configured to perform, after the calibration phase, the following steps:
• 4) measuring an optical signal representative of the evolution of the blood vessel during an acquisition period, by means of the photoplethysmography sensor;
• and
• 5) calculating an estimated signal representative of the evolution of the diameter of the blood vessel during the acquisition period, from the signal measured in the step 4) and the mathematical model determined in the step 3).