A fiber-based sensing system could help medical professionals to assess the health of the brain after a traumatic injury. [Image: Getty / Tom Warner]
Researchers from the UK and China have shown that a sensing system based on optical fibers could help health care teams to monitor patients for complications arising from brain trauma (ACS Sensors, doi: 10.1021/acssensors.4c02126). The automated system continuously tracks six separate biomarkers to provide crucial information about the health of the brain as a patient recovers from surgical treatment or a serious head injury.
A need for continuous monitoring
After a traumatic injury to the brain, such as a concussion, secondary damage can occur from swelling and inflammation within the brain tissue. Medical professionals typically monitor the ongoing impact of the injury by analyzing a series of biomarkers found in blood or spinal fluid, but conventional sampling methods struggle to deliver the comprehensive and continuous feedback needed to identify any problems and prevent further damage.
The new system overcomes that problem by using multiple optical-fiber sensors to track six key indicators of brain health: temperature; pH level; and the concentrations of dissolved oxygen, glucose, sodium ions and calcium ions. Each sensor is fabricated by functionalizing the tip of the fiber with a fluorescent film that is sensitive to one of the target analytes. When the fluorescent tip is excited by laser light, interactions with the target biomarker produce a change in brightness that can be detected with a spectrometer.
Six biomarkers with a single spectrometer
Continuous monitoring with the sensing system accurately detected changes in the target biomarkers, and the measured changes were consistent with the expected physiological response.
Crucially, the researchers exploited fluorescent materials with different excitation or emission wavelengths, allowing all six biomarkers to be measured using a single spectrometer and a laser that produces light at three distinct wavelengths. Machine-learning algorithms are then used to disentangle the fluorescence signals from one another, providing an easy readout of each biomarker.
The researchers incorporated the six fiber sensors, along with an extra one that was used to enhance the signal from the calcium ions, into a catheter-based system that can be inserted into the brain to measure the biomarkers in the cerebrospinal fluid (CSF). This strategy was tested using animal brains that had been immersed in artificial CSF to simulate the effects of a traumatic injury. Continuous monitoring with the sensing system accurately detected changes in the target biomarkers, and the measured changes were consistent with the expected physiological response.
The team also tested the system using samples of CSF taken from 11 healthy volunteers. After spiking the samples with the biomarkers of interest, the sensing system accurately measured the pH, temperature and level of dissolved oxygen, and it was able to identify increases in the concentrations of glucose and both sodium and calcium ions. According to the researchers, the sensing system “can selectively and accurately identify the target biomarkers, offering good precision and robustness in real clinical applications.”