Filter selection criteria for the discrimination of strongly overlapping chemical spectra

Abstract

Increasing the selectivity of sensors, while at the same time reducing their complexity, size and cost, are challenges to the sensing community. To this end, an area of exploration has been the development of filter-based chemical sensors. We have recently introduced an approach that utilizes multiple, broadband, infrared (IR) filters to enable discrimination of target chemicals, in the presence of potential interferents that have IR spectral signatures in a limited waveband. Our analysis technique, comparative discrimination spectral detection (CDSD), utilizes a set of broad IR transmission filters, to discriminate between a specific target chemical and multiple interferents with strongly overlapping IR spectra. We have demonstrated the ability of this technique to correctly distinguish between chemicals in the carbon -hydrogen stretch region of the IR absorption spectrum (2700 -3300 cm -1 ; 3.0 -3.7 µm).We present a numerical study exploring the choices of desired optical filter sets, and the resulting overall discrimination by these filter sets. Filter parameter choices, such as the peak transmission position and bandwidth, are fundamental in filter-based chemical sensing discrimination systems. In this paper, we describe a systematic numerical approach used to explore how optical filter properties, and filter overlap affect corresponding discrimination results. We describe the interaction between the overlapping spectra and various filter sets on both target and interferent chemicals. We discuss which filter parameters provide optimum selectivity for specific target chemicals and how this information can be utilized to select filters for future direct-filter sensors based on this methodology.

Demonstration of a Human Color Vision Mimic in the Infrared

“…The first step in the development of the CIE-IR chart is the selection of three IR optical filters, which are analogous to the three photopigments contained within the cone receptors in the human eye. , In order to provide discrimination between different chemicals, these optical filters must have significant spectral overlap with the vibrational absorption bands of the chemicals of interest. Such filters may be selected by any number of means; ,, in this study, a simulated annealing optimization approach was employed.…”

“…14,25 In order to provide discrimination between different chemicals, these optical filters must have significant spectral overlap with the vibrational absorption bands of the chemicals of interest. Such filters may be selected by any number of means; 8,26,27 in this study, a simulated annealing optimization approach was employed.…”

Biomimetic Optical-Filter Detection System for Discrimination of Infrared Chemical Signatures

“…Broadband optical filters for the IRFOB were selected by modeling the interaction of numerical filters (Gaussian) with experimentally generated IR single-channel power spectra of hexane, acetone, and fuel oil. , This resulted in an optimized numerical filter set consisting of three idealized Gaussian IR transmission filters which generated the greatest selectivity for the three chemicals of interest (Supporting Information). Once the optimized numerical filter set was identified, a search for commercially off the shelf (COTS) filters which matched the optimized numerical filter set as closely as possible was performed.…”