The rapidly evolving chemical sensor chemistry

The rapidly evolving chemical sensor chemistry is strongly related to photochemistry because the signal transmission or output of chemical sensors is caused by the interactions of an analyte with different spectral changes based on photophysical changes in the [sensor-chemical-analyte] set. The design principle of such sensor chemistry consists of three main processes: (1) to separate analytes, (2) to obtain a specific analyte from a complex mixture, and (3) to generate or amplify a signal based on analytical and supramolecular chemistry from a set [chemical-analytic] [89]. Compared to conventional analytical techniques, chemometers (chemical sensors) have received more attention from researchers in the chemical and materials science communities, mainly due to their unique properties, for example, low cost, small size for portability, high sensitivity and selectivity, and fast response for real-time on-site detection, etc. [90]. The rapid development of new techniques in chemical sensing has led to the availability of many useful sensors that are not based on electrical responses as an electronic nose solution, particularly optical sensors are notable among a variety of chemical sensors. The most common optical sensors are based on colorimetric or fluorescent changes due to intermolecular reactions between chromophores or fluorophores with analytes [79]. The chemical performance of optical sensors relies on the logical design of fluorophore or molecular chromophore structures [90]. By combining array-based techniques that use a diverse chemical set of interaction sensor elements with new digital imaging techniques, a hybrid response pattern can be generated as a unique optical "fingerprint" for each specific analyte. [79, 91, 92].