As people get older, it becomes increasingly difficult for them to find the right balance between self-determined living and the need for security and support: Older people, for example, fall more often or get into life-threatening situations because their heart or breathing stops.

The market therefore offers a variety of protection and monitoring systems for this target group, but they all have certain limitations: Body-worn systems such as bracelets can be easily removed and often have a stigmatising effect, as they immediately identify their wearers as “somewhat helpless”. Surveillance technology installed in the living space, on the other hand, usually generates images that can severely interfere with the private and intimate sphere of the residents and thus limit acceptance.

Prof. Dr. Andreas Diewald, a radar technologist at Trier University of Applied Sciences, is therefore developing a system in the VITASENS project that is intended to give its users security and preserve their dignity at the same time. The core of the project is a radar-based sensor that is unobtrusively attached to the ceiling of a room. From there it can monitor heartbeat and breathing rate as well as detect sudden falls. The trick is that the sensor does not take any real pictures of the people in the room. “Humans are represented by the device as some kind of “energy cloud”, not even the arms and legs are recognisable,” explains the project manager. “This means that the sensor can even be installed in intimate living areas such as bathrooms and toilets without violating privacy.”

Modern small radars enable new applications

This is made possible by the enormous technical progress in the field of radar technology. For about a decade now, there have been more and more small, low-radiation yet powerful devices that can be operated safely in the vicinity of people. Radar sensors detect the tiniest movements, for example the pulse beat under the skin or the lifting and lowering of the chest – and they do so completely independently of light, clothing, or bedclothes. Today, radar-based sensors are being developed to monitor premature babies, or as alarm sensors that draw attention to children forgotten in the car. Diewald has already worked on such developments and then turned to the question of where else such a device could be helpful. “Since several members of my family work in elderly care, the application in this area was obvious to me,” the scientist says.

The VITASENS project mainly focuses on applying the technology in nursing homes and residential homes. There, the devices are particularly useful for residents who are not yet in great need of help, explains Diewald: “These self-sufficient and fit people require less care and are therefore not under so much supervision, but they can still become seriously ill at any time.” However, the sensor is not designed to permanently monitor health data, the project manager emphasises: “Our sensor doesn't do any diagnostics, it only checks whether heartbeat and breathing are still there or not.” If these vital data fail, the device raises an alarm. After all, says Diewald, “you are not immediately dead if your heart and breathing stop. But of course, it is important to get help quickly in such a case.”

The sensor protects residents and relieves the staff

In nursing homes and residential homes, the radar sensor is supposed to fulfil a dual function: It protects residents from being left alone in dangerous situations – and it relieves the staff. The nursing staff have to concentrate on the persons in great need of care anyway, but the sensor prevents them from overlooking life-threatening situations with fitter residents. “The device is clearly intended as a supplement and support, not as a way to further reduce the number of caregivers,” says Diewald.

Diewald and his team spent the first year and a half of the project on building the sensor: The right combination of a dedicated chipset and specially developed antennas ensures optimal room illumination. The team also developed the signal evaluation from scratch. However, when it came to testing the device directly on site, in a care facility operated by the project partner Pflegeheim Holunderbusch GmbH, Corona thwarted all their plans: “We wanted to start taking measurements on site in February 2021,” reports Diewald. “But due to the pandemic, we were of course unable to carry out this part of the work yet.”

The on-site tests do not only include the function of the sensor, as this might be checked with test persons under laboratory conditions as well. More importantly, they are meant to evaluate the acceptance of the system by the home residents. Therefore, the team has also planned comprehensive surveys of the test persons. As the on-site tests are an important part of the work and cannot be omitted, the whole project will probably be extended until the end of the year.

Outpaced by technical progress

Apart from the consequences of the pandemic, Diewald says the project took its course mostly without difficulties – with just one drop of bitterness: As sometimes happens in science, the team was overtaken by technical progress. “While we were still painstakingly building our own antenna arrays, ready-made kits suddenly appeared on the market at reasonable prices,” Diewald says. He admits that this annoyed him at first but then adds that “from a scientific point of view, our development was still a success, even if it will probably end up in a drawer now. After all, we were able to gain a lot of new knowledge from this work.”

In any case, it will still be a long way until the radar sensor for room surveillance is commercially available. In the remaining project time, the team first wants to optimise the signal processing. Later on, the sensor is to be further developed towards application together with partner companies. On the way to series production, however, there are still a few questions to be answered: How can the device be secured against power and internet supply failures? Should it transmit the “energy cloud” images of the monitored persons, or is it sufficient to change the output to a simple traffic light system? And if the sensor is to be used not only in assisted living facilities, but also in private homes: How do you design the notification and rescue chain?

However, answering all these questions will probably no longer be Diewald’s task. His thoughts are already turning to various follow-up projects: Can the radar sensor also be of help to epilepsy patients? Might it be useful for the industry, as an environment recognition sensor on machines? And could it be applied in autonomous vehicles to monitor the driver's vital functions? In any case, Andreas Diewald has lots of new ideas – but turning them into a product ready for series production is usually out of his hands.