Highly parallel, 1060 nm interferometric diffusing wave spectroscopy with a time-of-flight filter

Area of Science:

• Biomedical Optics
• Neuroimaging
• Photonics

Background:

• Near-infrared (NIR) light technologies like interferometric diffuse optics (iDO) are emerging for brain signal monitoring.
• Coherent light fluctuations are key indicators of brain activity.
• Cerebral blood flow index (BFI) monitoring requires high-speed and accurate measurements.

Purpose of the Study:

• To demonstrate a line scan interferometric diffusing wave spectroscopy (iDWS) system at 1060 nm for BFI monitoring.
• To evaluate the system's performance on subjects with varying skin types and hair.
• To implement and assess a time-of-flight (TOF) filter for depth-resolved measurements.

Main Methods:

• Developed a line scan iDWS system operating at 1060 nm.
• Performed pulsatile BFI measurements on human subjects (Fitzpatrick Type V).
• Integrated an electronically tunable time-of-flight (TOF) filter using source wavelength tuning.

Main Results:

• Successfully demonstrated BFI measurements up to 5.5 cm source-collector separation.
• The TOF filter reduced scalp sensitivity by 2.92-fold at 4 cm separation compared to continuous wave (CW) mode.
• The system showed potential for high-throughput neuromonitoring.

Conclusions:

• The 1060 nm iDWS system with TOF filtering shows promise for improved depth sensitivity in neuromonitoring.
• This technology can enhance signal-to-noise ratio for brain signal analysis.
• Further optimization could lead to advanced non-invasive brain monitoring applications.