Properties of Spatial Pulse Wave Velocity and Spatial Peripheral Blood Flow Velocity using Magneto-plethysmogram and Photoplethysmogram

Hall elements that can detect magnetic fields changing according to the minute movements of a permanent magnet located above the wrist where the radial artery is embedded and photoelectronic devices that can detect changes in red blood cell light absorption according to variations in blood flow are utilized as medical sensors in digital healthcare diagnostic devices. The pulse waveform of the radial artery was measured using a magneto-plethysmogram (MPG), which is a clip-type pulsimeter, and the pulse waveform of blood flow was measured at the wrist and the ring finger using a photoplethysmogram (PPG). The spatial pulse wave velocity (SPWV) is calculated as the distance between MPG and PPG, denoted as L_H, divided by the time difference, denoted as Δt. This value is approximately a few meters per second. Δt refers to the time difference between the peak values of the MPG and PPG waveforms. The spatial peripheral blood flow velocity (SPBFV) is calculated as the distance between the wrist and the fingertip, L_H, divided by the time difference, denoted as Δτ, yielding a value of several tens of centimeters per second. In a preliminary study involving two participants in their twenties, the SPWV was approximately 1.2 m/s to 1.9 m/s, and the SPBFV between the radial artery at the wrist and the fingertip capillaries was about 19 cm/s to 25 cm/s. These results are believed to be influenced by the state of the vessels and blood flowing through the body. Based on big data obtained from simultaneous measurements of magneto-plethysmographic waveforms and photoplethysmographic waveforms using MPG and PPG, it is anticipated that an AI algorithm for diagnosing vascular and blood conditions in digital healthcare can be developed.