Changes in Measurement of Direct Current Photoplethysmography signals with a Wireless Transillumination System

Recent work has shown that it is possible to design a wireless system for the transmission of direct current photoplethysmography (DC-PPG) signals using photodetectors and Light Emitting Diodes and their application in the detection of the associated hemodynamic response in the spinal cord and brain in humans and various animal models. In this study, we have developed a system capable of wirelessly measuring and transmitting amplitude changes in low-intensity DC-PPG signals in humans from a transmitting to a receiving stage. To obtain changes in DC-PPG signals, to be wirelessly transmitted and received in a receiving stage, a transmitting circuit linked to four optodes was positioned on a test subject, of which one of them was arranged, in transmittance mode, on his index finger. At the same time, a baumanometer was placed on the humeral region of the subject’s right arm. In this way, we verified that our wireless system could measure a significant increase in DC-PPG amplitude due to compression episodes by the baumanometer. We suggest that the optode array arrangement of our system may allow wireless, real-time monitoring of the hemodynamic response in different regions of the human brain