Researchers in China have developed a biosensor chip that uses light to detect extremely low concentrations of biomarkers of traumatic brain injury (TBI) at concentrations as low as femtograms per milliliter. The technology could one day be used to make faster diagnoses after a head injury, helping doctors choose the best treatment course and providing early warning of complications.
“Although several biomarkers have been validated as indicators of TBI, current methods for measuring them are time-consuming and require multiple complex laboratory steps,” said Guangyuan Li, PhD, professor at the Beijing Institute of Technology. “To address this challenge, we developed metasurface biosensors that are exceptionally sensitive, allowing them to produce clear, reliable optical signals even when only tiny amounts of a biomarker are present.”
The biosensor achieves its sensitivity thanks to metasurfaces—ultra-thin materials with microscopic patterns etched on them, which enable the device to manipulate light very precisely. For this study, Li and colleagues coated a gold metasurface with antibodies that specifically target TBI biomarkers. When the target molecules bind to the antibodies on the metasurface, the light wavelengths it reflects change slightly, indicating the presence of the biomarker even at extremely low concentrations.
To test this approach, the researchers built two separate sensors targeting two key biomarkers of TBI: the glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein β (S100β). Results showed that the sensor could accurately detect subtle wavelength shifts depending on the biomarker concentration, with a sensitivity as low as under a femtogram per milliliter. This response was highly sensitive to the target biomarker, even when other biomarkers were present in the sample.
In recent years, light-based sensors have been increasingly gaining traction as diagnostic tools thanks to their potential to make biomarker detection much more precise compared to conventional methods, with promising applications currently being explored in early cancer diagnosis and real-time monitoring of diabetes.
However, more work will be needed before this technology can be routinely used in a clinical setting. With further development, the platform could be adapted to create metasurface sensors capable of detecting multiple biomarkers simultaneously to offer a more complete picture of a patient’s state in a short period of time. Going forward, Li and colleagues plan to continue working to reduce the costs of manufacturing the sensor, adapting fluid handling and packaging for clinical use, and ultimately validating the technology in clinical trials to assess its performance in a real-world setting.
“If developed into a point‑of‑care format, this technology could help provide faster and accurate answers after brain injury—perhaps using just a finger prick,” said Yunhui Liu, PhD, associate professor at the Shenzhen Institutes of Advanced Technology. “This could potentially reduce unnecessary CT scans for low‑risk cases while flagging higher‑risk patients earlier. It could also enable more accessible biomarker detection in ambulances, rural clinics, sports settings or emergency departments where time matters.”
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