PhotonWear develops new wearable sensors

04 Apr 2024

Finland's VTT leads consortium investigating new ways to monitor health and biomarkers.

A project launched by Finland's VTT applied research center is aiming to develop new wearable sensors for health monitoring.

The PhotonWear consortium includes VTT, GE HealthCare, ElFys, Bittium and the University of Oulu. The project is funded by Business Finland and is due to run until October 2025.

"Wearable sensors offer solutions to complex needs in the healthcare sector," commented VTT.

"The PhotonWear project is motivated by changes in society and demographic composition, such as the ageing of our population, which necessitates increasingly cost-effective solutions. Another perspective is that people are more and more interested in measuring their personal wellness."

VTT's previous research into photonics technologies has included the development of optical fibers made from cellulose able to help monitor conditions within built structures; and a hyperspectral camera paired with AI spectral analysis suitable for incorporation into consumer devices and food safety processes.

A key part of the PhotonWear technology will be black silicon photodetectors supplied by ElFys. Black silicon, first developed at Harvard by accident, uses a laser-based surface modification process to enhance the photoresponse of silicon and cause it to absorb almost all of the visible light striking it.

A black silicon photodetector can demonstrate up to 50 percent higher sensitivity compared to untreated material, according to the PhotonWear developers.

"The black silicon developed by ElFys enables much more accurate measurements compared to traditional photosensors, even when measuring weak light signals," commented ElFys CTO Antti Haarahiltunen, discussing the PhotonWear research. "As a result, you get higher quality data. In this project, we get to apply our technology in several applications of wearable health technology."

Stretchy comfortable skin-tight electronics

In March 2024 ElFys announced it was delivering the first customer samples of the company's black silicon-based photodetectors from a mass production foundry, with full scale manufacture of detectors at the facility due to begin in early 2025.

One focus for PhotonWear will be on using high-fidelity multispectral measurements as a route to monitoring parameters of interest, including blood pressure and the presence of particular biomarkers such as lactate and glucose, all via optical non-invasive methods.

"Nowadays, one place you find optical sensors is in smart watches measuring things like heart rate and its variability, but in this project, we are focused on improving sensor accuracy so that they are fit for medical use, while also making them much more comfortable to wear," commented Teemu Alajoki, coordinator of the PhotonWear project.

"We are aiming for flexible or even stretchy, extremely comfortable skin-tight electronics that are unnoticeable and reliable even in demanding use cases."

The project is also developing advanced data analytics compatible with wearable optical sensors. These kinds of devices can collect data continuously, so they can not only transmit the measured health data but also send automatic warnings if those readings appear dangerous. This could also include scenarios where a patient is discharged from hospital but then suffers worsening symptoms.