Wearable PPG signal sensors for real-time measurement in a weak magnetic field

Investigators: Jiří PŘIBIL, Anna PŘIBILOVÁ, Ivan FROLLO,  IMS SAS

 

Our research is focused in analyze and monitoring of a mental and physiological state of an examined person during scanning in the magnetic resonance imaging (MRI) device working with weak magnetic field up to 0.2 T. Our final aim is to detect and suppress negative influence of vibration and acoustic noise generated by the gradient system of the MRI equipment. Optical sensor based on photoplethysmography (PPG) principle is usable to monitor the state of the cardio-vascular system of a tested person which is mainly acquired by current heart rate (HR) and arterial blood pressure (ABP) values. Three prototypes of wearable PPG sensors using the wireless bi-directional Bluetooth (BT) communication for real-time data transmission were developed in our department.

Comparative measurements in laboratory conditions by the certified commercial pulse oximeter and a blood pressure monitor (BPM) device show good stability and proper accuracy of finally determined HR values. Measurement experiments inside the scanning area of the running MRI canner verify practical usability of sensed PPG signals for further processing and analysis. Additional testing shows, that the BT transmission in the scanning area has no visible influence on the quality of the finally obtained scanner images. On the other hand, using an external BPM device was not comfortable for tested persons and it brings some practical realization problems. Therefore, our current work is motivated to develop and apply an indirect cuffless approach to ABP values estimation directly from the PPG signal without use BPM device.

 

 

 

 

 

 

 

                                                             a)                                                                                                                                                                  b)

Fig. 1: Measurement inside the MRI E-Scan Opera tomograph: a) documentary photo of the experiment with PPG signal sensing by the PPG-BLE wearable sensor, b) user window of the PPGsensBT Windows control application.

 

Project: VEGA 2/0003/20 – Imaging methods based on magnetic resonance for medical diagnostics and material research.

 

Publications 2022:

 

  1. PŘIBIL, Jiří – PŘIBILOVÁ, Anna – FROLLO, Ivan. Comparison of three prototypes of PPG sensors for continuous real-time measurement in weak magnetic field. In Sensors, 2022, vol. 22, no. 10, p. 3769. ISSN 1424-8220. (3.847 – IF2021) Q1
  2. PŘIBIL, Jiří – PŘIBILOVÁ, Anna – FROLLO, Ivan. Evaluation of precision of three PPG sensor prototypes for measurement in weak magnetic field. In 45th International Conference on Telecommunications and Signal Processing (TSP 2022). – Brno, Czech Republic: Faculty of Electrical Engineering and Communication, Brno University of Technology, 2022, p. 1-5. ISBN 978-1-6654-6948-7. Q4
  3. PŘIBIL, Jiří – PŘIBILOVÁ, Anna – FROLLO, Ivan. Experiment with Cuffless Determination of Arterial Blood Pressure from PPG Signals Sensed by Wearable Sensors in a Weak Magnetic Field Environment, in Proceedings of the 9th International Electronic Conference on Sensors and Applications, 2022, MDPI: Basel, Switzerland, doi:10.3390/ecsa-9 -13220