BIAN: A Multilayer Microfluidic-Based Tissue-Mimicking Phantom for Near-Infrared Imaging

Area of Science:

• Biomedical Optics
• Neuroimaging
• Microfluidics

Background:

• Near-infrared spectroscopy (NIRS) monitors cerebral oxygenation, a key biomarker for neuronal activity.
• Simulating dynamic changes in oxygenation at different tissue depths is crucial for NIRS development.
• Existing tissue phantoms lack tuneable blood flow, volume, and optical properties for realistic simulations.

Purpose of the Study:

• To design, fabricate, and characterize a dynamic phantom using multilayer microfluidics.
• To create a phantom capable of controllable blood flow, blood volume, and optical properties.
• To test near-infrared spectroscopy (NIRS) instruments under simulated neurovascular coupling conditions.

Main Methods:

• Developed a multilayer microfluidic phantom embedded in silicone to mimic scalp and cortical vessels.
• Utilized a pump with programmable pressure control to simulate tissue oxygenation and perfusion.
• Employed a frequency domain NIRS instrument to measure optical changes in superficial and deep layers.

Main Results:

• The microfluidic phantom successfully simulated dynamic changes in blood flow and volume.
• NIRS instrument detected optical intensity variations corresponding to pressure-induced changes in the phantom layers.
• The phantom effectively mimicked functional brain activity and oxygenation changes.

Conclusions:

• A microfluidics-based dynamic phantom was successfully designed and fabricated for NIRS testing.
• The phantom accurately mimics brain functional activity and oxygenation dynamics.
• This technology holds promise for validating other optical imaging devices like DCS, pulse oximetry, and OCT.