A system and method for selective sampling of exhaled air in which the user exhales into the portable sampling device and the breath flow is calculated from the user’s air flow temperature obtained by the sensor. Furthermore, it is possible to correlate the air flow with the variation of temperature of the exhaled air.
The signal obtained from the sensor of temperature allows the detection of the user’s breathing cycles and the continuous calculation of the average time of expiration. The imposition of a breath pace (which is dependent on the subject age/genre defined previously) to the user, displayed in the graphical interface, allows the synchronization of the user breath cycle with the mathematically modelled breath cycle implemented in the algorithm. The synchronization of breath cycles coupled with the machine learning process, related with the calculation of the average time of expiration, assures a precise prediction of the instants for sampling of breath according to the desired respiratory origin.
The hardware module is responsible for processing, converting and transmitting the signal from the sensor to the software and, it also actuates on the valve of the portable sampling device to conduct the exhaled air according with the instants predicted by the algorithm for real time and/or offline analysis of a single or multiple exhalations.
The detection and monitoring of the exhaled air’s temperature, in this invention, solves the problems associated with capnography (measurement of the CO2 pressures and concentration) regarding the clear identification of the expiratory segments. Thus, this invention avoids the following problems: the variation of the composition and concentration of a sample of breath throughout the breathing cycle; the influence of speed of the breath which could affect the composition of the mixture between alveolar and dead space air and; the variation of the depth and frequency of breathing.
Moreover, the breath pace imposition and the machine learning algorithm that improves the synchronization of the mathematically modelled breath cycle with the breath cycle of the user allow a higher accuracy in the selection of the breath portion to sample/analyse and the reproductibility and repeatability of the desired breath samples.
The invention also overcomes the problems associated with equipment’s cost and exogenous contamination, the use of specialized personnel, lack of portability, low velocity of breath sampling and other the user dependency (e.g. age, genre, health status, etc.).
Stage of Development
TRL6 – Prototype developed and tested under several conditions with different age groups of users. Some improvements to the graphical interface of the software must be performed.
Patent application submmited (WO2018047058).
Paulo Henrique da Costa Santos
Fig. 1 – System for Selective and Controlled Sampling of Exhaled Air