A novel non-invasive, non-conductive method for measuring respiration

Abstract

We present a novel method for measuring dynamic changes in respiration parameters due to breathing based on the coupling of two ultra-high-frequency (UHF) antennae. For evaluation, we built a dynamic 3-D printed phantom encasing two compartments separated by an elastic diaphragm. By filling this artificial lung with air the effective permittivity in the compartment changes, resulting in a significant variation of the S21 parameter's magnitude and phase. We show that there is a strong linear correlation between the volume of air in the artificial lung and the magnitude (in dB) of the S21 parameter (R2=0.997) as well as the parameter's phase (R2=0.975). Our sensor system shows a high reproducibility (standard deviation of predicted volume =0.67 mL) and a timing similar to a conventional flow sensor (delay =5.33 ms). The presented method is a promising candidate to overcome some of the most important technical burdens of measuring respiratory parameters and might be used as a trigger for patient–ventilator synchronization in infants and neonates.