NIMO - Near Infrared Muscle Oxymeter

HOW IT WORKS

NIMO allows the measurement of the oxygenation state, using a NIRS (near-infrared spectroscopy) approach; this technique is based on the transparency of tissues to light in the NIR region (650-1000nm), as shown in the following images, where it is possible to notice the typical red spectrum of a white light which travels through a biological tissue, like a finger.

light in tissue

The main phenomena governing light propagation in the tissue are:

Absorption whose main effect is the intensity attenuation of the light, during its travel into the tissues. It is caused by the presence of some absorbers (chromophores) in the tissues; in the NIR spectral region, major absorbing compounds are water, lipids, oxyheomglobin (HbO2) and deoxy-hemoglobin (HHb)
Scattering: is a deviation from a straight trajectory by non-uniformities in the medium under test. The scattering of light induces an increase of the optical path length and a consequent increase of the optical attenuation of the light. Scattering allows NIR light to shine a tissue volume that is qualitatively similar to a banana-shape, as shown in the following image:

Volume under test

NIMO performs accurate optical absorption measurements at specific wavelengths that are converted into quantitative hemoglobin concentration (HbO2 and HHb) and thus tissue oxygen saturation (StO2 or TOI) using a proprietary algorithm.