Screen-printed wearable sensors for continuous respiratory rate monitoring: fabrication, clinical evaluation, and point-of-care potential

In this paper, we investigated the use of screen printing for the fabrication of a non-invasive wearable sensor, aimed at achieving accurate and continuous measurement of respiratory rate. The developed sensor was clinically evaluated on 15 healthy human participants, demonstrating its potential for point-of-care testing. Wearable sensors are emerging as the future of continuous healthcare monitoring by recording crucial physiological parameters that can be processed to monitor existing health conditions and predict future ones. Having a reliable tool to monitor respiratory rate is extremely valuable for healthcare professionals since it can indicate disease progression under certain conditions like COPD (chronic obstructive pulmonary disease) and COVID-19. The developed sensor was printed on a stretchable substrate consisting of repeated silver horseshoe patterns to avoid stress concentration and ensure conductivity at higher strains. By tracking changes in electrical resistance under strain, the sensor derived respiration frequency when placed on the chest. The clinical evaluation involved testing the sensor on 15 healthy human participants, aged 21–24, in sitting, standing, and Fowler's 45° positions, and a temperature-based airflow sensor was used as a reference. The screen-printed sensor accurately measured the respiratory rates with an error of 0.055 breaths per minute (bpm) demonstrating its accuracy and potential for point-of-care healthcare applications.