Optrodes: neurology’s leading lights
The need
Close monitoring of electrical activity in the brain and heart could lead to better treatments for disorders such as epilepsy, stroke, and heart arrythmia. However, the physics of electricity means the technology currently used to measure electrical signals has limitations.
The solution
Cutting-edge optical electrodes, or ‘optrodes’, are built with liquid crystals and optical fibres, rather than electrical wires. They leapfrog the limitations of traditional electrodes, clearing the way for researchers and clinicians to monitor electrical signals at very high resolution.
The human nervous system operates on electricity. Electrical impulses, produced at cellular level, ping at speed through sensory neurons to deliver information about the world to the brain. Fast-moving electrical signals go the other way, too, from the brain to the motor neurons, instructing muscles to move.
But disease, injury and the effects of ageing can disrupt the normal functioning of the body’s electrics, resulting in neurological disorders such as stroke, epilepsy, Parkinson’s disease, and heart conditions such as heart rhythm disorders (arrythmia).
For some time, it has been understood that close monitoring of electrical activity in the brain and heart has the potential to improve both diagnosis and treatment, leading to better outcomes for patients. Since 2016, ʹڲƱ researchers have been involved in the development of optical electrodes, or ‘optrodes’, capable of detecting signals down to the level of a single cell, opening up exciting applications in neurology and cardiology.
Our focus at the moment is the brain and heart, so things like heart rhythm disorders, epilepsy, Parkinson’s disease or even stroke … where the brain is still functioning, there’s thinking, but the patient can’t relay those signals to their hands or legs.
The optical advantage
Optrodes are tiny sensors that use a layer of liquid crystals to form a specialised mirror to convert an electrical signal into a light signal. That signal then travels through an optical fibre, offering massively greater data capacity than the electrical wires used in traditional electrodes.
“The good comparison is dial-up internet versus the NBN,” says Dr Amr Al Abed, a biomedical engineer with a focus on electrophysiology, who has been part of the optrode team for more than seven years.
While the optical fibres are capable of carrying much more information, the optrodes themselves are passive devices and will not interfere with the body’s own electrical signals. As a result, optrode arrays can be made as big or small as needed, taking accurate measurements at cell level across a large area, or focussing intensely on one tiny section of biological tissue.
Optrodes for the head, heart – anywhere
Currently, the team is focussed on conditions that affect the brain and heart, but in theory optrodes can be used on any organ in the body that has an electrical signal.
“It could even be the stomach or the bladder,” he adds. “The technology is the same.”
That opens up many possibilities, including the prospect of an implanted optrode array providing ongoing, real-time feedback to a therapeutic device. At the Australian National Fabrication Facility (ANFF), Dr Reem Almasri and ANFF-NSW Process Engineer have been working on light-weight, flexible polymer optrodes which promise to reduce the chances of rejection and scar formation in the body. It has already worked on the benchtop and must now go through rigorous materials testing to meet standards for biocompatibility before moving to any animal testing.
Miniaturising a concept from industry sensors
The idea to develop optrodes using liquid crystals and optical fibre technology first came in 2016 from Scientia Professor Nigel Lovell, head of the ʹڲƱ School of Biomedical Engineering and co-director of the Tyree Foundation Institute of Health Engineering, and Professor François Ladouceur, a colleague at the ʹڲƱ School of Electrical Engineering and Telecommunications and Director of the NSW ANFF node.
Nigel had previously worked with François, observing how his research team had used sensors with liquid crystal technology to detect different gases. The pair then began investigating if the sensors could be miniaturised for biological application. By 2022 the cross-school team, including Amr, had published .
Since then, research has continued, funded by grants from the National Health and Medical Research Council, and the Australian Research Council.
In 2023, the team, including Amr, Nigel, Francois, Josiah, Associate Professor Torsten Lehmann from the School of Electrical Engineering and Telecommunications, and David du Plessis founded a start-up, , to commercialise the technology.
The ability to go in the lab, put an electrode – or in our case an optrode – on a tissue, and see the signal from a cell. This tiny little cell, giving a signal, and you’re seeing it there in real time. It’s amazing
Optrode arrays for benchtop research
Embedding the use of optrodes into everyday clinical practice is a priority, but Amr is also involved in the development of a rigid optrode array – a scientific instrument that will enable researchers to study cellular electrical activity under the microscope. The start-up he and his colleagues have founded hopes to deliver this device and have it on the market within two years.
Currently, observing cellular electrical activity requires researchers to use techniques that employ either genetically modified cells, or a special dye that generates toxic by-products. The optrode array promises instant, easy and very precise observation of electrical activity under the microscope.
“Building the scientific instrument isn’t sidetracking,” notes Amr. “It’s just building up the tech on the way as we keep going towards the clinical aim.”
Optrodes and assistive technology
The other big application for optrodes in the future will be brain-machine or brain-computer interfaces, says Amr. The capacity to interpret brain signals could translate into instructions to move a powered wheelchair or dial a mobile phone, with life-changing impacts.
“They could just think ‘I want to move forward’ and the wheelchair would respond,” he explains.
This may take another decade, but Amr is thrilled to be contributing to such ground-breaking work.
“It’s a really good team to work with. And I really, really, really like electrophysiology. The ability to go in the lab, put an electrode – or in our case an optrode – on a tissue, and see the signal from a cell. This tiny little cell, giving a signal, and you’re seeing it there in real time. It’s amazing,” he says.