DESC:The general principle is to use the brain’s Haemodynamic response to detect the oxygen level of the brain tissue. Regional Oxygen saturation would be measured using fNIRS (Functional Near Infrared spectroscopy) which basically uses the spectrum of 700nm-900nm wavelengths of light where oxygenated and de-oxygenated hemoglobin are strong absorbers of light and this spectrum of light would not get absorbed by skin, tissues or bones.

Device Description:

The proposed construction of the head band is shown above which consists of a series of light emitting diodes (690nm, 805nm and 850nm) with the wavelengths mentioned above, one proximity sensor to detect the light reflected from the head for proximity sensing (10 mm) and a sensor placed at a distance of 25 mm from the LED sources capable of measuring NIR wavelengths is designed.
The reason for this construction is that NIR wavelengths cannot penetrate with enough intensity to be received through the absorption method and hence reflectance method is used for the design.

The above image shows the position of emitters and detectors with respect to the human brain where the light follows a ‘banana-arc’ path through skin, subcutaneous fat, scalp muscles and skull, eventually passing through superficial regions of cerebral cortex. In this scenario around 10 mm3 of the frontal lobe of the brain tissue is analyzed but this would be enough in practice to analyze the tissue oxygen levels of the brain.
The system simultaneously samples the proximal and distal sensors shown in the figure. The value received in the proximity detector represents possible outside contaminants on the signal which are filtered using an adaptive filtering algorithm from the signal received from the distal sensor. Then a pattern recognition algorithm runs to check if still any pattern or frequency corresponding to the proximal sensor is present in the distal sensor which is again filtered out to get the final signal which represents the blood oxygen absorption of the brain tissue.
Since fNIR uses light sources which emit light at a constant frequency and amplitude the changes in light intensity can be related to changes in relative concentrations of hemoglobin through the modified Beer–Lambert law.
Assuming constant scattering losses the equation is,

Where is the extinction co-efficient which is known for the system and d is the total corrected photon length. Photon path length in our application is derived empirically and fixed for the system which provides absolute quantification of Hemoglobin concentrations.

,CLAIMS:
1.A unique method uses a series of text which needs to be read by the user to the application and based on the final result of the pattern recognition the system gives the prognosis as stroke in progress and requiring immediate medical attention.

2.First of its invention developed to be interfaced to the Chest EEG/EEG unit which has been developed and is in testing as the Head Band along with the EEG electrodes.