Figure 2.

To capture the PPG waveform of near-infrared light, we assemble a set of basic blood oxygen measurement systems as a tool for research and experimentation, including red and near-infrared LED light sources, photodiode receivers, photoelectric system control chip circuits, and control firmware programs, using the MAX30101 module produced by Maxim as a front-end sensor to capture PPG signals. For a highly integrated Arduino module (Arduino Nano 33 BLE), we set the operating mode of the MAX30101 module through the SPI communication interface, receive the PPG waveform that has been converted into an electrical signal, and transmit the PPG waveform to the individual through the low-power Bluetooth interface (BLE) to the computer. A standard rechargeable 850 mAh lithium polymer battery powers the developed system to reduce the interference caused by noise that would distort the PPG waveform. The battery can be charged with the TP4056 charging module via USB power. The software program on the personal computer is responsible for preprocessing the original PPG waveform and then extracting the correlation of the near-infrared PPG waveform. A self-developed appropriate algorithm then analyzes the information to calculate the predicted systolic and diastolic blood pressure. (A) Assembled prototype. (B) Main components of the system. The analysis platform can be a personal computer or a Raspberry Pi single-board microcomputer.