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DEVELOPING A NEW FLEXIBLE BIOSENSOR FOR PRECISION HEALTHCARE
Both personalization and smart technologies are increasingly playing a role in our lives – and the healthcare industry is no exception. To that end, a team of researchers led by the American University of Sharjah has developed a flexible biosensor for enhanced precision healthcare.
Like industries such as banking, retail, and manufacturing, healthcare is expected to focus heavily on personalization and integration of smart technologies in the near future. Health biosensors combine both goals, with biocompatible electrodes implanted into the body to allow for monitoring of specific health metrics and even treatment of certain health conditions.
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Electrode-based biosensors, or bioelectrodes, typically have three parts: a biological-sensing component, a detector or transducer component, and a signalprocessing system. In the context of health, biosensors are analytical devices that convert a biological response into an electrical signal that conveys important information relating to the health of a patient, like blood glucose levels. Medical biosensors are typically either worn on the skin or implanted in the body.
Of these two modalities, implantable biosensors are the more challenging, as they must be small enough to be safely inserted into the body and remain stable over long periods of time. They must also be structurally and chemically suited to function within the body without being damaged or causing damage. Currently, most biosensors are made of precious metals like platinum, which makes them expensive to produce. They also tend to be too rough or rigid for use in the soft tissues of the human body.
Drilling down even further, implantable (neural) electrodes are becoming a very promising tool of clinical practice in the treatment of brain injury and neurodegenerative disease by recording nerve signals and stimulating nerve tissue. Neural electrodes are already being used in deep brain stimulation for treatment of conditions like epilepsy, Alzheimer’s disease, and Parkinson’s disease. However, the sensitivity and softness of nerve tissue makes it hard to implant such biosensors for lengthy periods of time as the materials typically used to make them can inflame – and even damage – such tissue.
In contribution to advancing precision medicine, a team of researchers led by the American University of Sharjah (AUS) has developed a low-cost and stretchable biosensing electrode that can be
-Dr. Amani Al-Othman, Associate Professor of Chemical Engineering American University of Sharjah
implanted into the nervous system. The research team was composed of AUS Associate Professor of Chemical Engineering Dr. Amani Al-Othman, AUS Professor of Electrical Engineering Dr. Hasan Al-Nashash, AUS Biomedical Engineering graduate Omnia Mohamed, AUS Professor of Biology, Chemistry, and Environmental Sciences Dr. Mohammad Al-Sayah, and University of Sharjah Assistant Professor of Sustainable and Renewable Energy Engineering Dr. Muhammad Tawalbeh. Dr. Fares Almomani, Associate Professor of Chemical Engineering at Qatar University, and Dr. Mashallah Rezakazemi, Lecturer in Chemical Engineering at Shahrood University of Technology in Iran, also contributed to the research.
Dr. Al-Othman explained the limitations of existing technology: “The nervous system is composed of delicate tissue, and the current electrodes are very stiff. They can damage the soft tissues in addition to being very expensive. Therefore, we aimed at developing a low-cost and flexible implantable electrode to treat peripheral nerve injuries.” To overcome these limitations, a team of researchers from the Neuroengineering Research Group at AUS combined nanoscale titanium dioxide with polymethyl methacrylate (PMMA) in a silicone polymer matrix.
Titanium dioxide is an inert powder used as a semiconductor, while PMMA is a biocompatible form of acrylic used in drug delivery as well orthopedic procedures to adhere bones. Silicone is a common material used in medical applications because it is durable, highly flexible, and chemically stable. Glycerol – a common food additive – was also used to improve the mixing process. The researchers tested a number of different ratios of silicone, PMMA, titanium dioxide, and glycerol to find the one that demonstrated the best conduction.
They found the best sample to be a combination of 50% silicone, 15% PMMA, 15% titanium dioxide, and 20% glycerol. The resulting bio-electrode was then subjected to characterization studies to measure its electron-transfer properties and kinetics, mechanical properties, and surface morphology alongside the stability of its electrochemical reactions. They also subjected the bio-electrode to a few weeks of immersion in a liquid solution meant to mimic the environment in the human body, taking it out on a weekly basis to see how its functional characteristics changed over time.
Testing of the team’s bio-electrode found it to have better resistance than graphene and platinum. Not only did observations reveal the biosensor to be stable over time, but its surface proved smoother than the plastics and metals typically used. The bio-electrode was also found to be highly elastic and stretchable, similar to the flexibility of skin and the spinal cord. The charge storage capacity of the electrodes was higher than both platinum and titanium, showing that the novel biosensor was better able to retain its charge than the currently available materials.
“The most surprising finding from our research was how well the material behaved when subjected to the long-term test, which was done by immersing it in body-like fluids for several weeks. We are very pleased that we were able to produce a bio-electrode material that is flexible and robust while low in cost, which has great potential for use in neural-sensing applications,” Dr. Al-Othman shared.
Left to right: Omnia Mohamed, Dr. Hasan Al-Nashash, Dr. Amani Al-Othman, Dr. Muhammad Tawalbeh, Dr. Mohammad Al-Sayah
A paper on this project titled “Fabrication of titanium dioxide nanomaterial for implantable highly flexible composite bioelectrode for biosensing applications” is scheduled for publication in the June 2021 issue of peer-reviewed scientific journal Chemosphere. Now that the team has demonstrated the basic functionality of its low-cost biosensor, the next step is to test its biocompatibility in vivo by implanting it in live laboratory animals.
“The fabricated electrodes in this work offer competitive characteristics, thus supporting their use in implantableelectrode applications. The bio-electrode also demonstrated promising impedance over the three-week immersion period. Although all the materials used in the electrodes’ fabrication are biocompatible, future studies should be directed at evaluating the biocompatibility of this composite electrode,” the research team wrote in its paper.
The researchers hope their novel biosensor can eventually make the leap from lab to market in order to contribute to the country achieving world-class healthcare, which is one of the UAE’s national priorities. The development of medical devices and other health-improving innovations is also a focus of the country’s Science, Technology & Innovation Policy as part of its efforts to boost the country’s non-oil economy. The global biosensor market is expected to reach $35.7 billion in value by 2025, according to Market Research Future.
“Healthcare is among the UAE’s priorities for its strategic development. The successful implementation of an implantable electrode like ours will certainly contribute to this vision of developing innovative and sustainable solutions to the many challenges faced by the country today, including the health sector,” Dr. Al-Othman concluded.
