Flexible, implantable electrode offers new insights into brain function

University of Waterloo graduate, and founder of Novela Inc., Dr. Salam Gabran A University of Waterloo graduate’s novel implantable microelectrodes are opening up promising new avenues for researching and treating vision and neural diseases, including epilepsy and amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s Disease.

Dr. Salam Gabran, an electrical engineer with a longstanding interest in deciphering how the brain works, has developed a tiny, flexible, electrode that takes neural recording and stimulation to new levels of performance.

His technology is currently being used by neuroscience researchers at Toronto Western Hospital and the Hospital for Sick Children to develop a therapy for epilepsy. “At the moment, in vivo testing shows that our technology is able to inhibit 90 percent of seizures, compared to 50 percent by current products,” he says.

The use of implantable electrodes to record brain function, and to stimulate neural activity, is not new. But current electrode technologies have their challenges. While miniaturization has helped to reduce the tissue trauma caused by rigid, thin-film electrode arrays, their smaller footprint limits their capability to capture clinically valuable electrical signals in the brain.

In 2007, working under his PhD supervisors Raafat Mansour and Magdy Salama in the University of Waterloo’s Centre for Integrated RF Engineering (CIRFE), Dr. Gabran set out to significantly improve the mechanical, electrical and biocompatible characteristics of electrodes by developing the first 3D, polymer-based electrode array capable of simultaneous recording and stimulation. His novel design, called the Waterloo Array, features a multi-layer architecture that allowed packing more channels into a minimized electrode footprint, increasing spatial resolution for recording and electrical stimulation applications.

His technology, a microscopically thin filament with a square cross-section and slender shaft, incorporates two seemingly incompatible structural requirements: the polymer electrode is flexible enough to conform to the brain’s uneven surface once implanted, but is mechanically engineered with sufficient axial strength to penetrate, needle-like, into brain tissue without support tools such as a stylus, reducing brain tissue damage.

Integrated with brain signal detection and analysis algorithms developed by collaborator Roman Genov and his team at University of Toronto, and with electrical impedance about 100 time smaller than commercial products, the electrode uses significantly less current, Dr. Gabran says. “Other systems do continuous stimulation, but our algorithms can predict seizures, so the electrode starts stimulation only when a seizure is detected.”

His “flex electrode” also displays a substantially longer lifespan. “Because of more advanced electrodes and algorithms, our power consumption is 15 times lower than current products. Our battery lifetime is 32 years; theirs is only 2.5 years.”

Dr. Gabran’s design includes a novel post-processing technique for reducing the fabrication cost of medical electrodes, where precious metals are often required and manufacturing costs are consequently steep.

CMC Microsystems supported his work throughout the development process, he says, from access to Ansys software for all mechanical and electrical modelling and simulation, to providing financial assistance for fabrication work. Packaging and integration, challenging because of the very small dimensions and very thin layers of their device, were made easier because of engineering support from CMC. “They help us find unconventional solutions for our unconventional problems,” he says.

The early promise of this electrode work was recognized in 2012 when Dr. Gabran and his co-developer Arezu Bagheri of University of Toronto, were awarded the MEMSCAP CMC Award for best microsystem design award. The electrode technology is now being commercialized through Novela Inc., a startup company formed in 2013 by Dr. Gabran and Professors Mansour and Salama. The company received a vote of confidence last year when Dr. Gabran received the Ontario Brain Institute’s Entrepreneur Fellowship Award, providing funding and mentoring to commercialize his technology.

The next step is human trials of the electrode. In the meantime, they continue to collaborate with research groups in North America, Europe and Asia on improvements and other applications of their flexible electrode, including an electrode for diagnosing ALS, vision research and a flexible antennae for contact lenses to detect biomarkers in tears, offering a non-invasive alternative to blood sampling.

Dr. Gabran and his team at Novela are also preparing to offer their multilayer flexible fabrication process to other innovators working in thin-film devices and circuits.

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