Photoplethysmogram sensors (PCVA sensors)

Photoplethysmogram (PPG) is a method of blood flow registration using infrared radiation source and photoresistor. Photoresistor changes resistance depending on the amount of absorbed light. The more the blood flow is, the less light is absorbed in body tissues, thus more light comes to photoresistor. Photoplethysmogram allows you to measure the volumetric blood pulse caused by periodic changes in the volume of blood with each heart beat, heart rate, heart rate variability.

Design features of PCVA sensor

In Rubicon polygraph:

  • Peripheral cardiovascular activity is registered from the palmar surface of skin with the help of "PCVA" sensor (marked "F" or "PCVA");
  • Type of sensor - photoelectric;
  • Gain ratio of 500;
  • Automatic and manual gain adjustment in the range of 1 - 64;
  • The sensor consists of a photopolymer casing, contact surface is concaved, on which there are two holes for infrared emitter and photoresistor. Inside the sensor casing a printed circuit board is located, providing the quality and reliability of operation, as well as the ability to change the signal gain in accordance with the requests of users;
  • The sensor is placed, as a rule on the palmar surface of any phalange of one of the fingers; the sensor fixation is performed with the help of bilateral Velcro type loop tape of 15 centimeters in length.

Specifics of PCVA sensor application

HEART RATE - is determined by the number of cycles of contraction - relaxation (acceleration - slowing).

AMPLITUDE – is the rate of change of the tone of vascular wall of arterioles (increase - decrease in vertical).

BASELINE OFFSET (vertical) - characterizes the intensity of activation and balance of stress - relaxation processes.

DICROTIC WAVE - differentiating features are the place of wave(s) position on dicrotism, the quantity and quality of waves.

Notes

In cases of reducing the baseline shift range in the course of research, it is necessary to reduce the density of the PPG sensor fixation on the finger.