Analytical procedure to assess the performance characteristics of a non-spectroscopic infrared optical sensor for discrimination of chemical vapors

Non-spectroscopic sensing enabled by electro-optical reservoir computer

“…This sub-section describes the operating principle and the modelling procedures of the sensing component used in this work. It is inspired by the biomimetic design which previously has been demonstrated successfully for chemical [18][19][20] and biological sample [21] detection. The biomimetic sensor mimics the operation of the human eyes, which are capable of discriminating over 100,000 shades of (visible) colour over an environmental background despite being equipped with only three main types of cone cells [22,23].…”

“…Research on colour sensitivity of mantis shrimp (Haptosquilla trispinosa), which has 12 different types of photosensitive cell covering different light wavelengths and polarisations, however, found that higher number of unique photoreceptors does not mean an improvement in colour discimination [25]; Mantis's spectral discrimination Δ𝜆 is in the region of 15 to 25 nm in comparison to humans' which is in the region of 1 to 8 nm [25,26] over the visible light region. In [18][19][20][21], a trichromat, three-colour, biomimetic sensor has been constructed in the mid-infrared range of light and a multi-variate statistics tool based on a patented comparative-discrimination spectral detection (CDSD) technique [20,27] has been used to perform the vectorial signal processing. In the present work, we have adopted a biomimetic sensor with a similar trichromat architecture, but the EORC is used for signal processing.…”

“…2. Figure 2(a) schematically shows the implementation of the biomimetic sensor constructed in [18][19][20]. The photodetectors are equipped with a filter at different central wavelength, in Fig.…”

“…Such sensors are readily available, for example as dielectric filtered photodetectors [28]. The specific parameter values of the sensor have been chosen as such they are broad and spectrally overlapped [18][19][20][21], see Fig. 2(b).…”

“…The choice of peak spectral response around the 3 µm of the mid-infrared range is motivated by the richness of carbon-hydrogen stretching fingerprints in this region [29]. Note that in previous works [18][19][20][21], the sensor has also operated at similar wavelengths of interest.…”