Cane toads play role in testing non-invasive monitoring device

Scientists at The University of Sydney have devised a new photonic radar system that delivers contactless, high-definition detection of vital signs. The system could be developed for use in a variety of clinical situations, such as intensive care units, for patients with critical health conditions, health monitoring in aged-care facilities and prisons, or in safety monitoring situations where drowsiness can cause accidents.

This type of monitoring is currently mostly achieved via wired or invasive contact systems, which can be inconvenient or unsuitable, eg, for patients with burns or for infants with insufficient skin area.

The scientists from The University of Sydney Nano Institute (Sydney Nano) and the NSW Smart Sensing Network wanted to address these issues by developing a photonic radar system that allows for highly precise, non-invasive monitoring. Their research has been published in Nature Photonics.

The newly developed and patented radar system was used to monitor cane toads and was able to accurately detect pauses in the toads’ breathing patterns remotely. The system was also used on devices that simulate human breathing. The scientists said this demonstrated a proof of principle for using photonic radar that could enable the vital-sign monitoring of multiple patients from a single, centralised station.

An advantage of this approach is the ability to detect vital signs from a distance, eliminating the need for physical contact with patients. This not only enhances patient comfort but also reduces the risk of cross-contamination, making it valuable in settings where infection control is crucial.

“Photonic radar uses a light-based, photonics system — rather than traditional electronics — to generate, collect and process the radar signals. This approach allows for very-wideband generation of radio frequency (RF) signals, offering highly precise and simultaneous, multiple tracking of subjects,” said lead author Ziqian Zhang, a PhD student in Sydney’s School of Physics.

“Our system combined this approach with LiDAR — light detection and ranging. This hybrid approach delivered a vital sign detection system with a resolution down to 6 mm with micrometre-level accuracy. This is suitable for clinical environments.”

Alternate approaches to non-contact monitoring have typically relied on optical sensors, using infrared and visible wavelength cameras.

“Camera-based systems have two problems. One is high sensitivity to variations in lighting conditions and skin colour. The other is with patient privacy, with high-resolution images of patients being recorded and stored in cloud computing infrastructure,” said University of Sydney Pro-Vice-Chancellor (Research) and research lead Professor Ben Eggleton, who is also the Co-Director of the NSW Smart Sensing Network.

RF detection technology can remotely monitor vital signs without the need for visual recording, providing built-in privacy protection. Signal analysis, including identification of health signatures, can be performed with no requirement for cloud storage of information.

Working with collaborators and partners in the NSW Smart Sensing Network, the researchers hope this research provides a platform to develop a cost-effective, high-resolution and rapid-response vital-sign monitoring system with application in hospitals and corrective services.

“A next step is to miniaturise the system and integrate it into photonic chips that could be used in handheld devices,” Zhang said.

 

Video credit: Faculty of Science, University of Sydney.

Image caption: Professor Ben Eggleton (left) with PhD student Ziqian Zhang in the Sydney Nanoscience Hub labs. Image credit: Stefanie Zingsheim.