Background: Hospitalized preterm infants often require months of vital signs monitoring in the neonatal intensive care unit. To date, wired sensors are essential for survival but are associated with numerous disadvantages, including sensor dislocations, skin trauma and hygiene risks. Non-contact vital sign monitoring would therefore represent a significant improvement in the care of hospitalized neonates.

Objective: This study aimed to develop a new microwave-based sensor for non-contact monitoring of vital signs.

Methods: We developed a radar-based vital parameter monitoring system for recording the respiratory rate of premature infants in a pediatric incubator. This novel sensor is a four-channel I/Q (In-Phase and Quadrature) radar system operating at 24 GHz with adapted antennas to cover the predefined area of interest on the body surface. As a proof of principle study, the system was tested in six anesthetized newborn piglets with a body weight between 1050 and 2710 g that were located in a newborn incubator.

Results: Using the radar-based system, thorax movements were detected and the respiratory rate was calculated. We observed high accordance between the signals of respiration detected by the novel microwave sensor and the signals of the cable-bound monitor at rest.

Conclusion: The novel microwave sensor is suited for measuring respiration in the piglet model. In the future, the sensor has to be optimized in order to improve its robustness against disturbances by heartbeats and body movements.

Significance: The study results have laid the foundation for non-contact monitoring of the respiratory rate, which could be used in neonatal intensive care units.