OxyMon Mk III is a flexible, research-grade system for continuous wave near-infrared spectroscopy. Configurations from 1 to 96 channels. OxyMon transmits via temperature stabilized pulsed laser light sources and measures via cooled avalanche photo diodes with ambient light protection. EEG and MRI compatible probes and mounts available.
The main characteristics of this highly advanced research tool are:
- Measures oxy-, deoxy-, and total hemoglobin concentration changes and optionally absolute concentrations and tissue saturation index.
- Stable, versatile and highly sensitive
- Various configurations, from 1 to 96 channels
- Fast data collection at 50 Hz as standard – up to 250 Hz is possible!
- No need to screen against ambient light
- The light detector cannot be damaged by ambient light
- Raw data (optical densities) easily accessible
- Standard configuration with two wavelengths per channel, up to 6 wavelengths is possible
- Data recording via PC using a free USB bus
- Simultaneous capture of other (physiological) data
- Compact, rugged, and portable device
- Can be used in hostile environments such as high altitudes and the Antarctic
- Unlimited data storage
- Hyperscanning possibilities
Customized Hardware and Software Options
- NMR/MRI compatible
- Customized options for Oxysoft
- Tissue Saturation Index (TSI)
- Arterial cerebral saturation measurement
- Special optical configurations
- Data input/output conversion box
- Brain-computer interface (see YouTube for an example made by the Sint Maartenskliniek for the BrainGain project)
- Multiple wavelengths (to measure ICG)
OxySoft NIRS acquisition and analysis software (5)
This is really dependent on the signal quality. Typically for normal cortical penetration you will want anywhere from 3cm up, the larger the distance the deeper the penetration however at the sake of a reduced signal-to-noise ratio. Typically for normal adults we employ a 3.5cm interoptode distance, for those with darker skin or dark/dense hair you may need to reduce this to achieve an ideal SNR. For younger children and infants often times 2.5cm is more common.
fNIRS is of course a completely different modality than fMRI, however while the mechanics may differ there is overlap in the resulting measurements, ultimately cerebral blood flow and metabolic measurements may be obtained, and neuronal activation often assumed. fNIRS is specific to oxygenated and deoxygenated hemoglobin measurement and quantification due to light back reflection, while fMRI aligns the orientation of the hemoglobin depending on the presence of oxygen. fNIRS offers a much better temporal resolution often 100x or more, while spatially fMRI has the upper hand by roughly 10x.
Very good, and important, question. Clearly fNIRS is employing frequencies of light that are purposely used to traverse the skull without much restraint, and this is in fact introducing exogenous stimuli. Well don’t fret, the amount of signal power using fNIRS can be comparable to sunlight. Further, of recent, several studies suggest there are various health benefits to infrared light stimulation at the cellular/metabolic level- even still these studies primarily employ chronic use.
This is a tough one, inherently hair is the nemesis of any fNIRS device on the market and while we all would like to say we have this completely figured out it ultimately comes down to proper preparation, part of which is also a skill in performing. I would use the same criteria with regard screening as you may normally do with EEG.
OxySoft is developed for use with Windows 7 or 10, both are supported however Windows 7 is still preferred. We also offer a free Android application for the PortaLite and PortaMon units for streaming and data logging.