Clothing as a vitality meter

Monitoring your own health and fitness with the help of your smartphone or wearables is becoming increasingly popular. Health apps are an incentive for many people to exercise more, help them to take their medication regularly and provide useful information on topics such as nutrition. In 2017, almost every second smartphone user was already using health apps, and according to the Federal Statistical Office, this sector had a global market volume of around 2.4 billion US dollars. By 2025, the market volume could even grow to around 11.2 billion US dollars. Global sales of wearables, i.e. mini-computers such as smartwatches and fitness trackers, have also increased more than tenfold since 2014 and already totalled around 445 million units sold in 2020.

Smart textiles

The vast majority of smart devices that have become everyday companions for many people are not suitable for medical use. However, their sophisticated electronics offer more and more possibilities for medical purposes. Various research groups are currently working on using this technology in items that are even closer to patients than smartphones and fitness bracelets: clothing. These smart textiles belong to the group of so-called clinical grade wearables and offer a decisive advantage: as patients wear them anyway, they cannot be forgotten and therefore offer the possibility of closer and more constant monitoring of the respective state of health.

The Fraunhofer cluster project „M³ Infekt“ is currently in the process of developing several such smart textiles. Under the leadership of the Fraunhofer Institute for Integrated Circuits IIS in Dresden, ten Fraunhofer institutes, the Magdeburg Hospital, Charité – University Medicine Berlin and the University Hospitals of Erlangen and Dresden are involved as medical partners.

One of these projects is „Pneumo.Vest“, for which researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS have developed a technology in which acoustic sensors in a textile waistcoat can detect lung sounds. The intelligent waistcoat is to be used for patients with severe respiratory or lung diseases and, according to the developers, will be a powerful addition to the classic stethoscope that pulmonologists have always used to listen to their patients' heart and lung sounds.

The technology behind it is based on piezoceramics: „When the piezoceramic deforms, a voltage is generated. And this voltage change can be measured. In principle, many small stethoscopes are installed in the waistcoat, which are arranged around the patient's thorax. This gives us the opportunity to record breath sounds and lung sounds at many different positions on the chest," says Ralf Schallert, group leader for characterisation methods at IKTS. The waistcoat is made of cotton because it has to be washable, breathable and easy to wear. The integrated sensor electronics can be removed and disinfected so that the hygiene requirements are met.

Visualisation of all areas of the thorax

Although its electronics can also be operated by battery, the „Pneumo. Vest“ is initially designed for bedridden respiratory patients, its sensors are supplied with power by cable and analysed and displayed on a PC. In contrast to the classic stethoscope, the waistcoat not only makes the sounds of the lungs audible, but is also equipped with specially developed artificial intelligence. In addition to preselecting the sounds that need to be diagnosed more precisely, it also provides the treating pneumologist with a visualisation of all areas of the thorax. „The sensor system therefore registers every sound produced by the lungs, no matter how quiet, all around the thorax. The software records these signals and outputs them electrically amplified. In addition, a visual representation of the measuring points of the lungs appears on a display. As the software knows the position of each individual sensor, it places its data directly at the corresponding point. This creates a detailed acoustic and visual scenario of the ventilation situation in all areas of the lungs,

explains Ralf Schallert.

Continuous monitoring of lung function

This provides pulmonologists with a more accurate and targeted diagnosis of the lungs. The Pneumo.Vest is not intended to replace the stethoscope and is not a substitute for the skills of experienced pulmonologists. However, an auscultation or even a lung CT always only represent a snapshot at the time of the examination. The added value of our technology is that it allows continuous monitoring of the lungs, even if the patient is not connected to equipment in the intensive care unit but is in the normal ward," emphasises Ralf Schallert. The Pneumo Vest method is also more comfortable for bedridden patients who have to be moved into the stable lateral position for a classic stethoscopy. The burden on doctors is reduced because they do not have to stethoscope their patients, but can diagnose the measurement results on the computer. And hospitals can use it to relieve their intensive care units, as the waistcoat works in the same way on normal wards.

Ideally, ventilated patients could even stay at home - their lungs would still be continuously monitored and any sudden deterioration would be reported immediately to the medical staff. Last but not least, the waistcoat could also be used in sleep laboratories, care facilities or for training prospective pneumologists. Interest in the waistcoat is correspondingly high. „Pneumo.Vest addresses exactly what we need. It gives us an instrument that expands our diagnostic options, relieves our hospital staff and makes the hospital stay more pleasant for patients," emphasises Dr Alexander Uhrig, specialist in infectiology and pneumology at Charité – Universitätsmedizin Berlin.

However, according to Ralf Schallert, it will be another three to five years before the product is ready for the market. The good thing about the project, however, is that it is already possible to work with the intermediate products. If you only look at the classic measurement of respiratory sounds, a doctor needs around a quarter of an hour to do this, the waistcoat can provide this for a large number of auscultation points after around three minutes.

 

Textile ECG system

Another example of clinical-grade wearables is the „ CardioTEXTIL“ project, which is currently being developed by the Fraunhofer Institute for Integrated Circuits (IIS). This garment – a so-called holster – is also able to record medical data around the clock. The target group here are patients with cardiovascular disorders and coronary heart disease. The textile belt system consists of a breathable polymer fabric that can be kept awake. Dry electrodes and signal lines are incorporated on the inside of the belt and rest on the chest. These pick up three ECG channels and transmit the measurement data to an electronic unit attached to the outside. It then calculates parameters such as heart rate and heart rate variability and can reliably recognise rare events such as arrhythmias.

Tight-knit patient monitoring

The decisive advantage here is also that the heart rate can be permanently monitored without the need for medical staff to carry out this measurement. In cardiac arrhythmias, the heart beats irregularly and often so quickly that it pumps less blood into the body. A total of two million people in Germany, Austria and Switzerland are currently affected by cardiac arrhythmias, and according to Fraunhofer IIS, this figure will double in the next 50 years. The problem with prediction, however, is that these cardiac arrhythmias often occur irregularly. They are typically diagnosed with the help of a 24-hour ECG (Holter ECG) – for which individual strips with electrodes are stuck to the patient's chest. The recorded data is either analysed on site in the practice or recorded using portable electronics.

However, wearing the device is very cumbersome, especially as the electrodes do not necessarily stick well and slippage leads to inaccurate results. However, if the cardiac arrhythmia occurs when the 24-hour ECG is not worn, it cannot be detected. The only way to truly monitor patients around the clock is with implantable loop recorders. „The CardioTEXTIL closes the gap between the classic Holter ECG with adhesive electrodes and the implantable loop recorder“, emphasises Dr Christian Münzenmayer, head of the Digital Health Systems department at Fraunhofer IIS. In principle, however, the system is not only suitable for patient monitoring, but also for sleep screening or performance diagnostics in professional sports.

Observation of heart function in everyday life

Thanks to the wireless transmission of the measured values via Bluetooth to a smartphone, the waistcoat is suitable for continuous monitoring of heart function in everyday life - without the need for measuring electrodes to be attached to the skin or implanted. The waistcoat itself only has an on/off button and is therefore extremely easy to use. If enough arrhythmias are detected within a certain time, the data can be automatically sent to the doctor, who can then make a diagnosis. This means that patients do not have to wear the waistcoat for a quarter of a year, but can take it off as soon as enough events have been detected. It provides pre-evaluated data over a much longer observation period, and therefore a reliable diagnosis. In addition, both patients and cardiologists need to make fewer on-site appointments," adds Christian Münzenmayer. Interest in the ECG waistcoat from doctors and clinics is correspondingly high. However, it will take another three to five years before it is ready for the market.

In the future, various sensor systems could even be combined in smart textiles of this kind, the expert predicts. This would make it possible to derive more complex clinical pictures and health conditions from breathing, heartbeat and skin conductance values, for example. It is also quite conceivable that a garment will have the ability to display something or make an input via it. So we can look forward to it.

Source: kma-online from 8 November 2022