Many rural regions are already grappling with limited access to medical care, particularly when it comes to high-quality diagnostic services. To address this gap, researchers at the Fraunhofer Institute for Reliability and Microintegration IZM are developing a solution that leverages radar technology.
In collaboration with several partners, they’re working on a mobile, low-power radar sensor system designed for non-contact patient monitoring. With this system, physicians can access vital information—like heart rate and respiratory rate—without requiring patients to wear sensors or devices on their bodies.
A high-frequency radar sensor system can replace the traditional ECG in selected applications in the future. Image Credit: Fraunhofer IZM
In a traditional ECG, the pulse is measured using electrodes attached to the patient’s body, with cables connecting them to a monitor. But for certain patient groups—those with severe burns or wounds, specific skin allergies, contagious diseases like COVID-19, or certain mental conditions—it can be difficult to apply electrodes and cables, making conventional ECGs challenging to use.
In the future, these vital signs could be recorded without contact using a high-frequency radar sensor system.
This non-invasive measurement technology enables healthcare providers to monitor vital signs continuously and remotely, allowing for a quicker response if abnormalities are detected. It also eases the workload for nursing staff and enhances patient comfort, as there’s no need to attach anything to the body or wear additional electronic devices.
Researchers at Fraunhofer IZM in Cottbus and Berlin are developing the new radar sensor system in close cooperation with 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.
Their shared goal is to tackle healthcare challenges—particularly in rural areas—using this contactless method. The German Federal Ministry of Education and Research (BMBF) is supporting the project through the Innovation Campus Electronics and Microsensors Cottbus (iCampus).
Vital Signs Measured Through a Mattress
The new 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.
Ivan Ndip, Professor and Head, RF & Smart Sensor Systems Department, Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration
This data can help identify medical issues related to the respiratory and cardiovascular systems, such as stress indicators or certain arrhythmias. It enables earlier detection of diseases linked to abnormalities in these systems. Once installed, the radar can pick up even the tiniest surface movements caused by breathing and heartbeats.
The potential use cases are diverse: monitoring infants, burn patients, people with sleep disorders, elderly patients in care homes, and even passengers in vehicles—especially children.
To prepare for clinical trials, the radar sensor system was enclosed in a plastic housing and placed under a hospital bed. During development, Fraunhofer IZM researchers factored in how the plastic case and the hospital environment could impact system performance, ensuring reliable operation. They thoroughly examined how the housing and bed affected antenna performance.
By adapting the design of the radar front-end and antenna systems, the radar’s range can be increased, allowing for flexible placement in a room, including mounting on walls or ceilings.
“The goal is to enable measurements at a greater distance from the patient and simultaneous monitoring of multiple patients in the future,” said 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 presents a significant challenge, mainly because the signals reflected from tiny chest wall movements are extremely weak. In addition, reflections from nearby people or objects, system noise, and movement from other parts of the patient's body can further complicate accurate detection. Addressing these issues requires advanced hardware design that delivers a high signal-to-noise ratio (SNR), combined with sophisticated signal processing algorithms.
The researchers at Fraunhofer IZM developed and fine-tuned 61 GHz radar antennas and a radar front-end board to integrate radar chips, antennas, and other system components while ensuring a high SNR.
They also systematically evaluated how manufacturing tolerances might affect system performance during the design of the antennas and front-end board, helping to ensure that the radar system remains reliable and robust. A specially designed antenna enables the team to focus electromagnetic waves along a narrow strip across the patient’s chest.
Since September 2023, a prototype of the medical radar system has been undergoing clinical trials at Thiem-Research GmbH (TRS), a subsidiary of the Medical University of Lusatia (Medizinische Hochschule Lausitz) — Carl Thiem in Cottbus. As part of the trials, project partners assessed how accurately the system measures vital signs and how those readings compare to a reference ECG.
“Initial measurements of test subjects lying in a supine, side or prone position went successfully,” Ndip said.
In the second phase of the BMBF project, the team successfully expanded the design into a multi-channel medical radar sensor system capable of simultaneously monitoring the vital signs of multiple individuals—entirely without contact.