Design And Experimental Study Of Wearable Respiratory Rate Monitoring System Based On Photoplethysmography

The respiratory rate is a vital parameter of chanracterization of respiratory that can provide valuable information about the health condition of a patient.Continuous and accurate recording ofrespiratory rate could prevent some serious illnesses,such as pneumonia,lessions of respiratory tract diseases.Current automatic RR measurement requires either an airflow detection method or the measurement of movement,volume and tissue concentrations.Both of these methods are obtrusive(particularly in the non-ventilated patient)and cumbersome to set up and hence do not lend themselves to general patient use.Using the convenient and comfortable way feed signal back.Aiming at these problem,a wearable devices for testing PPG sigals was conducted to extracting RR and Spo2 from PPG signals.This paper conducted two studies on the design requirements of the equipment:To explore the feasibility of extracting RR from a reflection-mode PPG detection system with green light LED,this paper develop a reflection-mode PPG detection system with 515nm wavelength.PPG signals were recorded at bradypnea/normal/tachypnea breathing rhythm to estimate respiratory rate,the respiratory wave was detected simultaneously with thermistor as reference signal.It is demonstrated that the proposed system could extract respiratory rate under 3 breathing conditions,and the calculated values are in good consistency with the reference values,which could be a supplement to the existing respiratory rate monitoring measurement.To study the penetration changes of 660nm wavelength LED and 940nm in the in the homogeneous phantom with Reduced Scattering Coefficient,on the basis of optical diffusion theory and other related concepts,a set of dual continued wavelengths sample measurement system for penetration depth and one device,by controling of the separation of light source and detector,which can quantitatively measuring the depth of penetration.The measurement results provide a good reference for the design of the probe.