The power of the Mid Infrared spectroscopy
MIR: Capturing the fundamental vibrations of biological molecules
The mid infrared wavelengths (between 2 and 20 µm) include fundamental vibration signatures of major molecules that compose the tissues and biological fluids.
Therefore, the absorption spectrum in mid-infrared of a biologic element is representative of its composition because it accurately reflects the structure of the molecules constituting the sample, providing a comprehensive metabolic profile.
One can quickly see the interest of such technique: instead of focusing on several biomarker because they are measurable, this technique detects the results of all markers in the sample, even the one we can’t identify or measure individually for now. This is more extensive and faster than metabolomics.
It is then possible to classify the spectrum of measured sample relatively to healthy cases and pathological cases references. This classification gives a score to help diagnosis.
Infrared spectroscopic analysis thus allows to obtain a score for a diagnosis from observation of all molecular characteristics of the sample (There is a very large number of distinct biomolecules present) and not based on the analysis of a small number of identified markers a priori.
A proven technology
The principle of spectroscopy (1st work in the fourteenth century) at large (gamma rays, X-rays, visible and ultraviolet, Infrared, Microwave, Radio Frequency) is used by a multitude of specialized experimental techniques. It is applied in almost all the fields of physics: astronomy, biophysics, chemistry, physics, atomic, plasma physics, nuclear physics, solid state physics, mechanics, acoustics ….
Infrared spectroscopy is a compelling technology for analytical chemistry, which two objectives are to identify and quantify some type of molecule in a complex sample.
It is widely used in academic research or industry as simple and safe technique of measurement, quality control and dynamic measurement.
Its use in the biological diagnosis has been restricted due to sampling methods.
Measurement by transmission by placing a sample between two infrared transmitting plates, is sensitive but complicated to implement.
By direct reflection or ATR plate; Implementation is simpler as sample has just to be deposited on the measurement area, but the sensitivity is limited.
SPIDTM platform is compact and easy to use. It brings the benefits of Mid Infrared analysis to every clinical practice
SPIDTM is based on a mid infrared spectroscope. It requires to operate a 50*40 cm flat surface and a standard power socket. Anybody can record an infrared spectrum in less than 10 minutes after a simple training of 2 hours.
Easy to use sensors
Diafir sensors are single use for more safety. They include a mid infrared fiber to measure a spectrum by Evanescent wave, as follows:
- When light circulating into the fiber reaches the fiber surface, it goes in and out the fiber due to its oscillating nature, this is the evanescent wave.
- This light wave can be absorbed by any component in contact with the fiber.
- The light recorded at the fiber exit is therefore input light minus the absorption of the liquid put onto the fiber: this is its infrared spectrum.
It is therefore possible to measure a liquid metabolic profile by placing a single drop (7µl) into the sensor.
To get a diagnostic out of this metabolic profile, Diafir developed a genetic algorithm to identify relevant wavelengths. They are selected within a learning group made out of patients spectra associated with a known diagnostic. These wavelengths are the used to build up a mathematic formula establishing a diagnostic score. This formula is then tested against a second group of patients with a known diagnostic, the validation group.
Once validated, this diagnostic formula is integrated into the SPID platform to deliver a diagnostic score at the very end of the spectrum measurement.
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