Scalable, modular continuous wave functional near-infrared spectroscopy system (Spotlight).

Area of Science:

• Neuroscience
• Biomedical Engineering
• Signal Processing

Background:

• Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique.
• Existing fNIRS devices can be bulky and lack portability, limiting their application in real-world scenarios.
• Advancements in portable and modular fNIRS systems are crucial for expanding neuroscience and brain-computer interface (BCI) research.

Purpose of the Study:

• To introduce Spotlight, a novel fiberless, portable, and modular continuous wave-functional near-infrared spectroscopy (fNIRS) system.
• To enhance the accessibility and power of fNIRS devices for neuroscience and BCI applications.
• To provide designs that can foster further innovation in fNIRS technology.

Main Methods:

• Developed a modular fNIRS system (Spotlight) with palm-sized modules containing high-density LED and silicon photomultiplier detector arrays.
• Embedded optoelectronic components in a flexible membrane for optimal scalp coupling.
• Validated system performance using phantoms and conducted a human finger-tapping experiment with custom 3D-printed caps.

Main Results:

• Demonstrated sensor characteristics through phantom validation.
• Successfully captured motor cortical hemodynamic responses during a finger-tapping task in human subjects.
• Achieved offline decoding accuracy of median 69.6% (up to 94.7%) for task conditions, with comparable real-time accuracy.
• Observed a correlation between custom cap fit, hemodynamic response magnitude, and decoding accuracy.

Conclusions:

• Spotlight represents a significant step towards more accessible and powerful fNIRS systems.
• The modular and portable design facilitates broader application in BCI research.
• Improved cap fit enhances the quality of neuroimaging data and decoding performance in fNIRS studies.