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Item type:Publication, Access status: with files , Radar-based inspiratory-to-expiratory time ratio estimation: a validation study(Springer, 2026-03-04); ; ; Respiration is a key indicator of health and wellbeing, with metrics such as respiratory rate (RR), inspiratory time (TI), expiratory time (TE), and the inspiratory-to-expiratory time (I:E) ratio offering insights into conditions ranging from acute life-threatening and chronic diseases to symptom management. While traditional methods already measure these parameters with high accuracy, they still require contact-based sensors, limiting their practicality for continuous monitoring. This study evaluates radar as a non-contact alternative by validating multiple radar-derived respiratory metrics against impedance pneumography measurements in 30 healthy volunteers at rest. Synchronous recordings from both modalities were analysed to assess agreement across methods using descriptive statistics, scatter plots, modified Bland-Altman plots, and equivalence testing (TI: ±0.3 s, TE: ±0.3 s, RR: ±2 brpm, I:E ratio: ±0.2). Equivalence testing indicated high correlation (p ≤ 0.001***) across all metrics, with 81.8% (TI), 77.6% (TE), 97.2% (RR), and 85.7% (I:E ratio) of values within predefined bounds. These findings highlight radar's potential for continuous respiratory monitoring, particularly in medical fields where minimizing patient burden is essential as in palliative, post anaesthesia, and intensive care settings.Publicationtype: Journal Article28 11 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , PEPbench - Open, reproducible, and systematic benchmarking of automated pre-ejection period extraction algorithmsThe pre-ejection period (PEP) is a widely used cardiac parameter in psychophysiology that reflects the duration between the onset of ventricular depolarization and the opening of the aortic valve. PEP is often used as a marker of cardiac sympathetic nervous system (SNS) activity, particularly in within-subject comparisons under similar hemodynamic conditions. While many algorithms for automated PEP extraction from electrocardiography (ECG) and impedance cardiography (ICG) signals (more precisely, its first derivative, dZ/dt) have been proposed in literature, they have not been systematically benchmarked. This lack of standardized algorithm comparisons originates from the absence of open-source algorithms and annotated datasets for evaluating PEP extraction algorithms. To address this issue, we introduce PEPbench, an open-source Python package with different Q-peak and B-point detection algorithms from literature that can be combined to create comprehensive PEP extraction pipelines, and a standardized framework for evaluating PEP extraction algorithms. We use PEPbench to systematically compare 108 different algorithm combinations. All combinations are evaluated on two datasets with manually annotated Q-peaks and B-points, which we make publicly available as the first datasets with reference PEP annotations. Our results show that the algorithms can differ vastly in their performance and that B-point detection algorithms introduce a considerable amount of error. Thus, we suggest that automated PEP extraction algorithms should be used with caution on a beat-to-beat level as their error rates are relatively high. This highlights the need for open and reproducible benchmarking frameworks for PEP extraction algorithms to improve the quality of research findings in the field of psychophysiology. With PEPbench, we aim to take a first step toward this goal and encourage other researchers to engage in the evaluation of PEP extraction algorithms by contributing algorithms, data, and annotations. We hope to establish a community-driven platform, fostering innovation and collaboration in the field of psychophysiology and beyond.Publicationtype: Journal Article38 21 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fast determination of the monostatic radar channel in the near-field of electrically large targetsThis contribution addresses the determination of the radar channel when operating in the near field of electrically large targets, which is a common scenario in modern short-range radar applications such as vital-sign sensing. With the focus on computational simplicity and the inclusion of near-field scattering phenomena, the proposed approach combines physical optics (PO) concepts and the far-field radiation pattern of the radar antenna to determine both amplitude and phase of the receive signal. The numerical implementation relies on basic scalar evaluations. The agreement between the simulated and measured radar channel of a metallized human-body-shaped object at 24 GHz and 61 GHz proves the effectiveness of the approach.Publicationtype: Conference Paper16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 3D-printed Pickett-Potter horn with a sine-squared antenna profile(IEEE, 2025-09); ; ; ; This contribution discusses a design approach for Pickett-Potter horn antennas optimized for additive manufacturing. A hybrid approach combines a sine-squared antenna profile with a discrete step for mode conversion, enabling easier manufacturing while achieving a highly Gaussian radiation characteristic. A V-band antenna is designed, optimized and manufactured. Far-field measurements validate the proposed approach.Publicationtype: Conference Paper103 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Radarbasierte Atemerfassung auf einer Palliativstation(Thieme, 2025-04-28); ; ; Zusammenfassung: In der Palliativversorgung werden technische Hilfsmittel wie EKG oder Pulsoxymetrie nur sparsam eingesetzt, um Zuwendung und Beziehungsarbeit nicht zu stören. Gleichzeitig ist Symptomerkennung essenziell und viele Patient*innen können diese nicht selbst äußern. Diese Studie untersucht erstmals den Einsatz eines Radarsystems zum berührungslosen Atemfrequenzmonitoring bei Palliativpatient*innen. In einer prospektiven Studie wurde radarbasiertes Atemfrequenzmonitoring mit einer Goldstandardmethode bei stationär behandelten Palliativpatient*innen verglichen. Die Auswertung bei 13 Patient*innen zeigte eine Übereinstimmung der Atemfrequenzerfassungen durch Radar und Gold-Standardverfahren (n=13, Korrelation r=0,93; 88% der Atemfrequenzen innerhalb ±2 Atemzügen im Vergleich zu Goldstandard). Verlaufsanalysen ergaben Hinweise auf ein Potenzial zur Symptomerkennung. Radarbasiertes Atemfrequenzmonitoring unter klinischen Bedingungen ist zuverlässig und hat das Potenzial, Symptome zu erkennen.Publicationtype: Journal Article33 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Near-field scattering phenomena in monostatic radar applications derived from physical opticsIn the context of radar, this article examines phenomena that occur in conditions where the physical extent of the target cannot be considered negligible compared to the range and, thus, far-field assumptions are violated. Based on physical optics principles, a transfer function of the radar channel between the antenna input and output power wave is derived for a monostatic configuration. The effects are studied using a circular metallic disk as an exemplary target. Exact and approximative expressions for the transfer function are derived incorporating the influence of the antenna radiation characteristic in addition. Measurements with targets of different sizes performed with horn as well as open-ended waveguide antennas at 24 and 61 GHz validate the phenomena of receive power level fading and nonlinear phase distortion.Publicationtype: Journal Article71 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 54 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Soziale Implikationen von Gesundheitstechnologien in der Palliativversorgung – Entwicklung eines konzeptionellen Rahmenwerks(Thieme, 2024-08-26); ; ; ; Weisser, A.Neue Gesundheitstechnologien wie beispielsweise Apps, radarbasierte Messtechniken oder Robotik bieten Potentiale zur Unterstützung der Palliativversorgung. Ihr Einsatz führt zu sozialen Auswirkungen in der Versorgungspraxis, die vielschichtig, teils verzögert erkennbar und zu berücksichtigen sind. Da soziale Teilhabe und zwischenmenschliche Begegnungen in der Palliativversorgung zentrale therapeutische Konzepte ausmachen ist hier besondere Vorsicht geboten. Gesundheitstechnologien dürfen die Grundsätze der Palliativversorgung nicht stören oder beeinträchtigen. Um dies sicherzustellen sind die sozialen Auswirkungen von Gesundheitstechnologien bei deren Entwicklung und Nutzung fortlaufend zu analysieren und zu berücksichtigen. Bislang fehlt eine Konzeptionalisierung sozialer Implikationen von Gesundheitstechnologien in der Palliativversorgung. Zur Erforschung sozialer Implikationen von Gesundheitstechnologien in der Palliativversorgung wurde zwischen September 2022 und Juli 2023 ein sequentielles Forschungsdesign mit Methoden der qualitativ-empirischen Sozialforschung angewandt: (1) Zunächst wurden iterative interdisziplinäre Diskussionsrunden durchgeführt und mittels konzeptioneller Mapping-Methode ausgewertet. Darauf aufbauend folgten (2) drei Fokusgruppen mit Forschenden, medizinischem Personal und einer Patient-and-Public-Involvement Gruppe, welche mittels qualitativ strukturierter Inhaltsanalyse ausgewertet wurden. Mit den Ergebnissen wurde ein Rahmenwerk – das CARE-HAUS Rahmenwerk – entwickelt, dessen Anwendbarkeit in zwei Fallstudien (3) beispielhaft anhand von radarbasierten Messtechniken und Wearables zur Bewegungsüberwachung überprüft wurde. Das Forschungsdesign wurde von fortlaufenden iterativen narrativen Literaturrecherchen begleitet. Das CARE-HAUS Rahmenwerk konzeptualisiert soziale Implikationen von Gesundheitstechnologien in der Palliativversorgung. Es zeigt Bereiche auf, in denen Gesundheitstechnologien förderliche und potenziell hinderliche Auswirkungen auf die Versorgungspraxis haben können, wobei die Grundsätze und Zielsetzungen der Palliativversorgung als Maßstab gelten. Die identifizierten Bereiche umfassen die beteiligten Akteur:innen und ihre Charakteristika, Interaktionen, Rollen, Aufgaben und Prozesse im Versorgungskontext und schließlich gesellschaftliche, strukturelle, organisatorische und fachliche Rahmenbedingungen. Das CARE-HAUS Rahmenwerk bietet eine Orientierung für die Analyse sozialer Implikationen vor und während Technologieentwicklungen und -implementierungen. Künftig muss die Anwendbarkeit des CARE-HAUS Rahmenwerks in weiteren Studien evaluiert werden.Publicationtype: Conference Paper59 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , EmRad: ubiquitous vital sign sensing using compact continuous-wave radars(IEEE, 2024-06-28); ; ; ; In biomedical monitoring, non-intrusive and continuous tracking of vital signs is a crucial yet challenging objective. Although accurate, traditional methods, such as electrocardiography (ECG) and photoplethysmography (PPG), necessitate direct contact with the patient, posing limitations for long-term and unobtrusive monitoring. To address this challenge, we introduce the EmRad system, an innovative solution harnessing the capabilities of continuous-wave (CW) radar technology for the contactless detection of vital signs, including heart rate and respiratory rate. EmRad discerns itself by emphasizing miniaturization, performance, scalability, and its ability to generate large-scale datasets in various environments. This article explains the system's design, focusing on signal processing strategies and motion artifact reduction to ensure precise vital sign extraction. The EmRad system's versatility is showcased through various case studies, highlighting its potential to transform vital sign monitoring in research and clinical contexts.Publicationtype: Journal Article75 48 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Integration approach for radar transceiver MMICs with integrated antennas enabling adaptability to customized passive frontend design(IEEE, 2024-06); ; ; ; Commercially available, low-cost radar transceivers tend to integrate all radio frequency (RF) components including the antennas, thus omitting an accessible RF interface. This limits their use for applications with special requirements, such as application-specific antenna designs. To overcome this drawback, a novel integration concept is presented that adapts integrated transceivers employing antennas-in-package (AiP) in radar systems with customized passive RF front-ends. The approach is demonstrated with a continuous-wave (CW) 61-GHz radar system tailored to the needs of medical research studies aiming to explore the morphology of the human pulse wave. The approach features 3D-printed freeform rectangular waveguides (RWG), an AiP-to-RWG transition, a 3D-printed horn fed lens antenna, and a directional coupler to implement a monostatic radar based on a commercial bistatic AiP-transceiver. Simulation and measurements validate the fulfillment of the application-specific requirements.Publicationtype: Conference Paper90