A Clinically Evaluated Interferometric Continuous-Wave Radar System for the Contactless Measurement of Human Vital Parameters
Fabian Michler,
Kilin Shi,
Sven Schellenberger,
Tobias Steigleder,
Anke Malessa,
Laura Hameyer,
Nina Neumann,
Fabian Lurz,
Christoph Ostgathe,
Robert Weigel,
Alexander Koelpin
Affiliations
Fabian Michler
Institute for Electronics Engineering, Faculty of Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstraße 9, 91058 Erlangen, Germany
Kilin Shi
Institute for Electronics Engineering, Faculty of Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstraße 9, 91058 Erlangen, Germany
Sven Schellenberger
Chair for Electronics and Sensors Systems, Brandenburg University of Technology, 03046 Cottbus, Germany
Tobias Steigleder
Department of Palliative Medicine, Medical Faculty, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
Anke Malessa
Department of Palliative Medicine, Medical Faculty, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
Laura Hameyer
Department of Palliative Medicine, Medical Faculty, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
Nina Neumann
Department of Palliative Medicine, Medical Faculty, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
Fabian Lurz
Institute for Electronics Engineering, Faculty of Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstraße 9, 91058 Erlangen, Germany
Christoph Ostgathe
Department of Palliative Medicine, Medical Faculty, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany
Robert Weigel
Institute for Electronics Engineering, Faculty of Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstraße 9, 91058 Erlangen, Germany
Alexander Koelpin
Chair for Electronics and Sensors Systems, Brandenburg University of Technology, 03046 Cottbus, Germany
Vital parameters are key indicators for the assessment of health. Conventional methods rely on direct contact with the patients’ skin and can hence cause discomfort and reduce autonomy. This article presents a bistatic 24 GHz radar system based on an interferometric six-port architecture and features a precision of 1 µm in distance measurements. Placed at a distance of 40 cm in front of the human chest, it detects vibrations containing respiratory movements, pulse waves and heart sounds. For the extraction of the respiration rate, time-domain approaches like autocorrelation, peaksearch and zero crossing rate are compared to the Fourier transform, while template matching and a hidden semi-Markov model are utilized for the detection of the heart rate from sphygmograms and heart sounds. A medical study with 30 healthy volunteers was conducted to collect 5.5 h of data, where impedance cardiogram and electrocardiogram were used as gold standard for synchronously recording respiration and heart rate, respectively. A low root mean square error for the breathing rate (0.828 BrPM) and a high overall F1 score for heartbeat detection (93.14%) could be achieved using the proposed radar system and signal processing.