The sensing device could be used in various clinical scenarios, including brain injury, stroke, and brain tumor resection
A new study has demonstrated that a tiny bundle of optical fibers can continuously, accurately, and simultaneously measure six biomarkers of brain health, helping to prevent serious complications that can follow a traumatic brain injury.
Optical fiber technology, a.k.a. fiber optics, uses pulses of light to transmit data along a bundle of thin strands of glass or plastic. It's a technology that, more often than not, is closely associated with the internet, a means of achieving things like faster download and upload speeds and reduced latency.
A new study led by Imperial College London (ICL) has used the technology to improve healthcare, particularly the diagnosis and treatment of dangerous swelling that can follow a traumatic brain injury.
"Continuous and comprehensive brain monitoring is crucial for timely identification of changes or deterioration in brain function, enabling prompt intervention and personalized treatments," said the researchers. "However, existing brain monitoring systems struggle to offer continuous and accurate monitoring of multiple brain biomarkers simultaneously."
Brain monitoring after a traumatic brain injury (TBI) is critical to patient care. After the initial injury, the brain swells, a delayed response known as a secondary injury. Swelling presses the soft brain tissue against the hard, inflexible skull, causing further damage. Secondary injury is the leading cause of hospital death. Unlike the initial injury, secondary brain injury can be mitigated by closely monitoring parameters such as EEG, intracranial pressure (ICP), cerebral blood flow, and brain oxygen levels. Separate devices are currently used to measure these parameters.
For the present study, the researchers took advantage of technological advances to create a bundle of optical fiber sensors that simultaneously monitor six biomarkers that are indicative of brain health: temperature, pH, and concentrations of dissolved oxygen, glucose, sodium ions, and calcium ions. The biomarkers are measured using cerebrospinal fluid (CSF), the watery liquid that fills and surrounds the brain and spinal cord and provides nutrients, removes waste, and acts as a shock absorber for these delicate organs.
The tips of six optical fibers were fitted with fluorescent sensors, which, by using a multi-wavelength laser, enabled the selective and continuous measurement of each of the biomarkers. A spare optical fiber was included in case it was needed for signal enhancement or a seventh biomarker. The fibers were bundled up into a 2.5-millimeter-thick (0.1-inch) catheter, which was initially inserted into animal brain models of TBI. Machine learning algorithms were used to decipher the incoming biomarker measurements.
After demonstrating that the device could continuously and accurately measure the six biomarkers in animal brains, the researchers moved on to validating their findings using clinical human CSF samples. They obtained samples from 11 patients and used the optical fiber sensing system to measure the select biomarkers.
"In the measurement of clinical human CSF samples, the multiplexed sensing system demonstrated high sensing precision for the continuous measurement of multiple biomarkers simultaneously with high selectivity and stability," the researchers said. "Therefore, we conclude that the sensing system, coupled with intelligent algorithms, possesses great potential in the multiplexed monitoring of deep brain biomarkers for TBI treatment."
The device is not limited to only measuring six biomarkers, though.
"In the current design, the system is developed for the monitoring of six biomarkers simultaneously with one spare fiber to accommodate a seventh biomarker," said the researchers. "However, it is not the maximum capacity of the system. With careful optimization of the connector and individual fiber dimensions, it has the potential to measure more than 10 biomarkers concurrently. Achieving this would require additional lasers with varying wavelengths to efficiently excite all of the sensors."
And the researchers say the sensing device could be used in other situations.
"The device also holds potential to be utilized with other modalities," they said. "The device's optical fiber-based design offers full compatibility with magnetic resonance imaging (MRI), making it suitable for use in MR-guided surgeries with long-distance fibers and remote monitoring capabilities. It could also be integrated with drug delivery systems, utilizing hollow fibers to directly measure responses to pharmacological interventions. Further studies are necessary to assess the performance of the sensing system in diverse environments to fully explore its potential in multiplexed sensing and beyond."
The researchers said that the probe's small size and its being made from soft, highly biocompatible materials reduce the risk of it damaging brain tissue and prompting an inflammatory response, making it suitable for long-term implantation. However, the biocompatibility of the system needs to be evaluated over extended periods.
"The system is minimally invasive, multiplexed, sensitive, selective, robust, and fully reversible and suitable for long-term applications," the researchers concluded. "It holds great promise for precise and continuous monitoring of deep brain physiology, aiding in pathological identification and clinical guidance in various clinical cases, including but not limited to brain injury, ischemic or hemorrhagic stroke, and brain tumor resection."