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Many rural regions are already facing a shortage of medical care, which is particularly acute when it comes to high-quality diagnostics. Researchers at the Fraunhofer Institute for Reliability and Microintegration IZM plan to use radar technology to help with this issue. Working in collaboration with partners, they are developing a mobile low-power radar sensor system for non-contact patient monitoring. The physicians receive details of the patient’s vital signs, such as heart and respiratory rate, without the patient having to wear a sensor on their body.
In a traditional ECG, the pulse is measured using electrodes attached to the patient’s body and connected to the monitor with cables. But for some patient groups, such as those with severe burns or wounds, certain skin allergies, contagious diseases such as COVID-19 or certain mental disorders or conditions, it can be difficult to attach electrodes and cables to the body and use a traditional ECG to measure their vital signs. In the future, this kind of examination can be performed with no contact using a high-frequency radar sensor system. This non-invasive measurement technology allows healthcare professionals to monitor a patient’s vital signs continuously and without contact from a distance and take action quickly in the event of any abnormality or discrepancy. This new method for measuring vital signs makes nursing staff’s work easier. The patients benefit from increased comfort, as there is no need to attach electrodes and cables to the body, nor do they have to wear any additional electronic devices. Researchers at Fraunhofer IZM in Cottbus and Berlin are developing the innovative high-frequency radar sensor system in close collaboration with researchers at Brandenburg University of Technology Cottbus-Senftenberg (BTU), the Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH), the Leibniz Institute for High Performance Microelectronics (IHP) and Thiem-Research GmbH. The project partners aim to address challenges in health care, especially in rural regions, with their novel contactless examination method. The German Federal Ministry of Education and Research (BMBF) is funding the project as part of the Innovation Campus Electronics and Microsensors Cottbus (iCampus).
Vital signs measured through a mattress
The new radar sensor can measure vital signs such as a patient’s heart and respiratory rate through clothing, blankets and even through a mattress and transmit the information to monitoring devices. “The radar sensor system uses the radar chips and antennas to generate electromagnetic waves that are reflected by the body. The reflected waves are modulated by the rhythmic motion of the chest wall due to respiratory and heart activity. This can be measured and analyzed using the radar sensor system to extract the vital signs,” says Prof. Ivan Ndip, head of the RF & Smart Sensor Systems department at Fraunhofer IZM, explaining how the innovative high-frequency radar sensor system works. Based on this, medical aspects of the patient’s respiratory and cardiovascular systems, such as stress factors or certain cardiac arrhythmias, can be identified. Thus, many diseases and conditions associated with anomalies of these systems can be detected at an earlier stage. Once installed, the medical radar can detect the smallest movements on the surface of the body, caused by the patient’s breathing and heartbeat. There are many prospective applications of the medical radar sensor system, ranging from the monitoring of infants, burn victims and people with sleep disorders, to patients in nursing homes, and even drivers and passengers in vehicles, especially children.
In order to carry out clinical trials, the radar sensor system was integrated into a plastic case and installed under a hospital bed. During the development of the radar sensor system, Fraunhofer IZM researchers took into consideration the effects of the plastic case and the real-world environment where the system will be used, so as to prevent any malfunction during operation. Particularly, the impact of the plastic case and the hospital bed on the antenna performance were thoroughly investigated during the design phase. By adapting the design of the high-frequency front-end board and the antennas, the range of the radar sensor system can be extended, so that it can be flexibly positioned in the room in future, and can also be attached to walls and ceilings. “The goal is to enable measurements at a greater distance from the patient and simultaneous monitoring of multiple patients in the future,” says Uwe Maaß, a colleague in Ndip’s team.
Systematic development and optimization of the antennas and radar front-end board enable reliable functionality of medical radar sensor system
Reliable contactless measurement of vital signs using radar is a big challenge, espe-cially since the signal reflected by micro-movements of the chest wall is very weak. Furthermore, signals reflected from people or objects in the patient’s vicinity, system noise and movements of other parts of the patient’s body also make it challenging to reliably measure vital signs. Overcoming this challenge requires innovative hardware design solutions that ensure a high signal-to-noise ratio (SNR), along with powerful signal processing algorithms.
The researchers at Fraunhofer IZM developed and optimized the 61 GHz radar antennas and radar front-end board for integration of radar chips, antennas and other system components to ensure a high SNR. Furthermore, the effects of manufacturing tolerances on system performance were systematically considered and analyzed during the development of the antennas and front-end board to ensure reliable and robust functionality of the medical radar sensor system. A special antenna design allows the experts to focus the electromagnetic waves on a specific narrow strip along the patient’s chest.
The prototype of the medical radar system has been used in clinical tests by Thiem-Research GmbH (TRS), a subsidiary of the Medical University of Lusatia (Medizinische Hochschule Lausitz) — Carl Thiem in Cottbus, since September 2023. During this clinical investigation, the project partners tested how reliably the system measures vital signs and how the measurements correlate with the reference ECG. “Initial measurements of test subjects lying in a supine, side or prone position went successfully,” Ndip says. In the second phase of the BMBF project, the experts succeeded to extend the design to a multi-channel medical radar sensor system that has the potential to measure vital signs of multiple individuals simultaneously, all without contact.
https://www.fraunhofer.de/en/press/research-news/2025/may-2025/contactless-patie...
The new radar sensor logs the activity of patients’ heartbeat and respiration and transfers the data ...
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