A small ultrasound patch monitors heart or vascular movements over a prolonged period, whilst a wearable sensor records muscle activity or supports continuous blood pressure monitoring: in future, wearable ultrasound could continuously monitor physiological and mechanical processes within the body directly on the human body. Whilst fitness trackers and other wearables have long since become part of everyday life, many ultrasound wearables are still at the research or early development stage. Sensor expert Professor Christian Kupsch from TU Bergakademie Freiberg, together with his co-authors, explains why this is the case and how the transition from the laboratory to real-world applications can be accelerated in a recent article in Nature Sensors.
Unlike many established wearables, which primarily detect electrical or optical signals at the body’s surface, ultrasound can provide information from deeper tissue structures. This opens up new possibilities for continuous medical monitoring, rehabilitation or human-machine interaction. “The technical foundations for wearable ultrasound systems are essentially in place today. In recent years, there has been significant progress in wearable ultrasound transducers, electronics and signal processing,” says Kupsch. “Nevertheless, many promising demonstrators have so far failed to make the leap from the laboratory to practical application.”
Common platforms for faster development and comparability
The authors see a key hurdle in the lack of widely accessible development platforms that can be used to investigate new applications and compare different system concepts. “Open and reconfigurable hardware and software platforms – i.e. those that can be adapted for different applications – could play a significantly greater role in the development of new ultrasound wearables,” explains Kupsch. “They can make research results more comparable and reproducible. At the same time, application teams would not first have to develop a complete ultrasound system themselves for every new research question.”
Such wearable ultrasound platforms combine key functions such as signal generation, data acquisition, signal processing and communication within a customisable development environment. For example, researchers in medicine, rehabilitation or human–machine interaction can investigate new applications without needing to be specialists in all aspects of ultrasound electronics themselves.
From the authors’ perspective, this therefore also requires additional investment in open research infrastructures, open-source projects and shared platforms. These can create a common technological foundation upon which different research groups can build and test new applications more quickly.
System design determines the path to the product
A comparison with the ultrasound machine found in a doctor’s surgery illustrates just how great the technical challenge is: What is achieved there with a large device and powerful electronics must be scaled down to just a few centimetres for a wearable and operate for long periods on a small battery. Wearable ultrasound systems must therefore make do with very little energy and space, whilst at the same time offering sufficient processing power, data transfer rates, signal quality and wearing comfort.
The crucial step is not just to keep improving individual components. We need to understand how transducers, electronics, signal processing, communication and the respective application interact as an integrated system. This is precisely where shared platforms can help – from the initial application experiment right through to a manufacturable system.
