WO2022173432A1 - Optical system for analyte detection - Google Patents

Abstract

An optical system includes a fluorescence-based chemosensor configured to emit fluorescence upon reaction of a chemo sensing molecule with an analyte, a source of modulated light configured to generate a beam of light having a wavelength in response to an excitation wavelength of the chemosensor, the light being carried over free space, a collimating lens configured to collimate and diffuse the modulated light, a dichroic mirror arranged to reflect the modulated light onto the chemosensor and transmit re-emitted light from the chemosensor onto a photodetector, and a lens located upstream from the photodetector configured to focus the re-emitted light onto the photodetector.

Description

OPTICAL SYSTEM FOR ANALYTE DETECTION

TECHNICAL FIELD

[0001] The present disclosure relates to a fluorescence-based chemosensor, specifically real time analyte chemosensor in an aqueous medium such as real-time ammonia chemosensor, and a method of using the same.

BACKGROUND

[0002] Identification and monitoring of various ions such as heavy metals and minerals in water and other liquid media has been utilized in various industries including agriculture, water management, and medical analysis. Various fluoresce-based chemosensors have been developed, but there are obstacles to their use, especially for complex media whose composition complicates analyte detection. An additional obstacle is developing a device capable of detecting the fluorescence generated by the chemosensor in a meaningful and practical manner.

SUMMARY

[0003] In one or more embodiments, an optical system is disclosed. The optical system includes a fluorescence-based chemosensor configured to emit fluorescence upon reaction of a chemo sensing molecule with an aquacultural analyte and upon light excitation, a source of modulated light configured to generate a beam of light having a wavelength in response to an excitation wavelength of the chemosensor, the light being carried over free space, a collimating lens configured to collimate and diffuse the modulated light, a dichroic mirror arranged to reflect the modulated light onto the chemosensor and transmit re-emitted light from the chemosensor onto a photodetector, and a lens located upstream from the photodetector configured to focus the re-emitted light onto the photodetector, the optical system being enclosed in a waterproof, corrosion-resistant housing. The aquacultural analyte may be ammonia. The optical system may be a real-time analytical sensor. The lens may be an asymmetric lens configured to focus the re-emitted light before the re-emitted light enters the photodetector. The optical system may also include one or more colored filters. The optical system may be housed in a portable aquacultural aqueous media sensing device.

[0004] In another embodiment, a real-time ammonia sensing device for aquacultural aqueous media is disclosed. The sensing device includes an optical system having a source of light configured to generate a beam of light having a first wavelength to be carried over free space, a collimator configured to collimate the light, and a dichroic mirror configured to reflect the collimated light at the first wavelength onto a fluorophore-containing chemosensor configured to react with an analyte within an aquacultural aqueous media sample and transmit a light re-emitted from the chemosensor having a second wavelength onto a photodetector. The sensing device also includes an electronic system having a microprocessor programmed to receive a signal corresponding to the re-emitted light from the photodetector and to provide information based on the signal in real-time. The first wavelength is an excitation wavelength of the chemosensor. The second wavelength is different from the first wavelength. The optical system and the electronic system may be sealed from contact with the aquacultural aqueous media. The device may be portable. The device may include a waterproof, corrosion resistant housing. The chemosensor may be housed in a compartment accessible by the aquacultural aqueous media.

[0005] In yet another embodiment, an aquacultural media ammonia sensing device is disclosed. The device includes a housing including a source of modulated light configured to generate a beam of light having a first wavelength depending on an excitation wavelength of a fluorescence- based chemosensor, the light being carried over free space, a collimating lens configured to collimate and diffuse the modulated light, a dichroic mirror configured to reflect the modulated light onto the chemosensor and transmit re-emitted light from the chemosensor onto a photodetector, and a lens located upstream from the photodetector configured to focus the re-emitted light onto the photodetector. The ammonia sensor further includes a compartment attached to the housing and including the fluorescence-based chemosensor configured to re-emit the light upon reaction of a chemo sensing molecule with ammonia in an aquacultural aqueous media sample. The housing may be waterproof and corrosion resistant. The compartment may be configured to enable contact of the chemosensor with the aquacultural aqueous media. The housing may also include an electronic system including a microprocessor programmed to receive a signal from the photodetector. The microprocessor may be programmed to communicate with another electronic device. The device may be a portable device. The device may be a real-time aquacultural ammonia sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic depiction of the photoinduced electron transfer (PET) mechanism utilized in chemosensors;

[0007] Figure 2 is a combined graph typically used to predict unknown concentrations of the ion/analyte in an aqueous environment by measuring the fluorescence from a chemosensor;

[0008] Figure 3A is a schematic depiction of a chemosensor structure including a matrix network with embedded microparticles and a surfactant system disclosed herein;

[0009] Figure 3B shows a detailed view of a section of the chemosensor of Figure 3 A;

[0010] Figure 3C shows a detailed view of the microparticle with the surfactant system of

Figure 3B;

[0011] Figure 3D shows a non-limiting example of a chemo sensing molecule of the chemosensor disclosed herein;

[0012] Figure 4 shows a non-limiting example of the chemosensor disclosed herein incorporated into a chemo sensing structure including multiple layers;

[0013] Figure 5 displays a graph showing results of a real-time titration experiment using sea water as the aqueous medium, ammonia as the analyte, and the chemosensor disclosed herein to identify the analyte in the medium;

[0014] Figure 6 shows a non-limiting example of an optical analytical system employing the chemosensor disclosed herein; [0015] Figure 7 shows another non-limiting example of the optical system having the chemosensor disclosed herein;

[0016] Figure 8 shows a device using the optical and electrical system with the chemosensor disclosed herein; and

[0017] Figure 9 shows an exploded view of the compartment housing the chemosensor within the device shown in Figure 8.

DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

[0019] Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the disclosure. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the disclosure implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed.

[0020] The first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation. Unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.

[0021] It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.

[0022] As used herein, the term “substantially,” “generally,” or “about” means that the amount or value in question may be the specific value designated or some other value in its neighborhood. Generally, the term “about” denoting a certain value is intended to denote a range within ± 5% of the value. As one example, the phrase “about 100” denotes a range of 100 ± 5, i.e. the range from 95 to 105. Generally, when the term “about” is used, it can be expected that similar results or effects according to the disclosure can be obtained within a range of ± 5% of the indicated value. The term “substantially” may modify a value or relative characteristic disclosed or claimed in the present disclosure. In such instances, “substantially” may signify that the value or relative characteristic it modifies is within ± 0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or 10% of the value or relative characteristic.

[0023] It should also be appreciated that integer ranges explicitly include all intervening integers. For example, the integer range 1-10 explicitly includes 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Similarly, the range 1 to 100 includes 1, 2, 3, 4. . . . 97, 98, 99, 100. Similarly, when any range is called for, intervening numbers that are increments of the difference between the upper limit and the lower limit divided by 10 can be taken as alternative upper or lower limits. For example, if the range is 1.1. to 2.1 the following numbers 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 can be selected as lower or upper limits.

[0024] In the examples set forth herein, concentrations, temperature, and reaction conditions

( e.g ., pressure, pH, flow rates, etc) can be practiced with plus or minus 50 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples. In a refinement, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 30 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples. In another refinement, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 10 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples.

[0025] For all compounds expressed as an empirical chemical formula with a plurality of letters and numeric subscripts (e.g., CH2O), values of the subscripts can be plus or minus 50 percent of the values indicated rounded to or truncated to two significant figures. For example, if CH2O is indicated, a compound of formula C(o.8-i.2)H(i.6-2.4)0(o.8-i.2). In a refinement, values of the subscripts can be plus or minus 30 percent of the values indicated rounded to or truncated to two significant figures. In still another refinement, values of the subscripts can be plus or minus 20 percent of the values indicated rounded to or truncated to two significant figures.

[0026] As used herein, the term “and/or” means that either all or only one of the elements of said group may be present. For example, “A and/or B” means “only A, or only B, or both A and B”. In the case of “only A,” the term also covers the possibility that B is absent, i.e. “only A, but not B”.

[0027] It is also to be understood that this disclosure is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present disclosure and is not intended to be limiting in any way. [0028] The term “comprising” is synonymous with “including,” “having,” “containing,” or

“characterized by.” These terms are inclusive and open-ended and do not exclude additional, unrecited elements or method steps. The term “including” or “includes” may encompass the phrases “comprise,” “consist of,” and/or “essentially consist of.”

[0029] The phrase “consisting of’ excludes any element, step, or ingredient not specified in the claim. When this phrase appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0030] The phrase “consisting essentially of’ limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.

[0031] With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

[0032] The term “one or more” means “at least one” and the term “at least one” means “one or more.” The terms “one or more” and “at least one” include “plurality” as a subset.

[0033] The description of a group or class of materials as suitable for a given purpose in connection with one or more embodiments implies that mixtures of any two or more of the members of the group or class are suitable. Description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among constituents of the mixture once mixed. First definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation. Unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property. [0034] Securing the quality of water has been a worldwide focus. Efforts have been made to remove contaminants in drinking, but also waste water, reprocessed water, and also water used for aquaculture. Some of these contaminants are heavy metal ions, such as lead ions (Pb²⁺), arsenic ions (As³⁺ or As⁵⁺), mercury ions (Hg²⁺), chromium ions (Cr²⁺ or Cr⁶⁺), or cadmium ions (Cd²⁺), which can pose detrimental health effects on humans, animals, and/or aquatic life. Among the important analytes are dissolved ammonia (NEE) or gaseous NEE in water.

[0035] Ammonia is a nutritious, inorganic nitrogen compound that is found naturally in the air, soil, water, and living tissues. But ammonia may require regular monitoring. This is related to toxicity of NEE in water adversely affecting living organisms. An increased level of ammonia in waste and reprocessed water is also of importance as it directly affects the yield of water treatment process efficiency. In sea water for aquaculture, ammonia directly affects the health and yield of the farm organisms. An improper level of NEE can affect the entire aquaculture pond, potentially damaging the entire crop. In fresh water sources, e.g. in agriculture, over-fertilization increases the levels of NEE, resulting in ground water pollution. It is also important to monitor the level of NEE in drinking water due to health reasons. Hence, detection of MB is important in any type of water in various environments.

[0036] But ME detection in any aqueous media has been technically challenging. This is due to the presence of both ME and NH-f forms in water. The chemical equilibrium of concentrations of ME and ME⁺ depends mainly on different factors, including temperature, pH, and salinity of the aqueous medium ME and ME⁺ may be present in. An ionized form of ammonia is not harmful, but it is difficult to separate NH-f from ME during detection in water using conventional approaches.

[0037] Ion sensing techniques have been employed in detecting ions in a fluid medium (e.g. water). For example, fluorescence-based detection methods have been utilized to sense ions, including heavy metal ions in water, where an ion binds to a detecting molecule (e.g. a chemosensor) to either generate or quench fluorescence. Measuring the fluorescence can subsequently determine concentration of the ion in the water. [0038] Yet because different ions have different sizes and charges and require different binding energies when binding to different detecting molecules, the conventional fluorescence-based detection methods may exhibit different sensitivities toward the sensing of different ions. Therefore, to accurately detect the presence of a target ion in a fluid medium, a detecting molecule needs to selectively bind to the target ion with a high sensitivity. The difficulty associated with separation of NH ⁺ from Mb during detection thus leads to difficulty during sensing as the NH-G may bind to the detecting molecule instead of the desired Mb or vice versa.

[0039] To measure Mb using chemical sensing methods, majority of the existing technologies is focused on using a “chemical filter” or microporous hydrophobic membrane approach for filtering out hydrophilic ions such as Ca²⁺, Mg ²⁺, Na⁺, and NH4⁺. Dissolved Mb then interacts with pH sensing molecule immobilised in the hydrophobic matrix generating an optical signal, which is either calorimetric or fluorescence in nature. But an additional technical challenge related to MB in aqueous media is its measurement range. Generally, Mb in water requires trace level detection, making pH sensor-based approach difficult as changes in the pH from trace level Mb interaction may not be sufficient to meet the sensing resolution required for Mb in water. Additionally, dissolved CO2 or any other trace organic molecules may also interfere with the pH sensing molecule due to its selective filtration into the hydrophobic matrix layer, influencing Mb detection using pH sensor approach.

[0040] Typically, a receptor-spacer-fluorophore type of sensor may be used to identify ions/analytes. Such sensor may utilize photoinduced electron transfer (PET). An example chemosensor and the PET principle are shown in Fig. 1. The chemosensor 10 may include fluorophore 12. The fluorophore 12 is covalently linked to an ion/analyte receptor 14 via a non-conjugating spacer group 16. In the absence of the ion/analyte 18, the unbound receptor 14 has a higher energy than the excited fluorophore 12. This energy difference, among other factors, drives rapid electron transfer from the receptor 14 to the excited-state fluorophore 12, thus quenching the fluorescence. When the receptor 14 is bound to the ion/analyte 18, the energy level of the receptor’s electron pair is lower than that of the excited fluorophore 12; the electron transfer is not energetically favoured, and thus, fluorescence is “switched on.” [0041] The change in the fluorescence intensity with respect to the ion/analyte concentration may be utilized to create a master curve, example of which is shown in Fig. 2, which may be used to predict unknown concentrations of the ion/analyte in the aqueous environment by measuring the fluorescence from the sensor. Such chemosensors have been used to realise a low cost, highly sensitive (ion concentration in ppm range), in-line, real-time sensors for water quality monitoring.

[0042] It is important to note that the PET effect described above may be facilitated only in a hydrophilic environment. Thus, to facilitate the sensing mechanism, atypical chemosensor design uses a hydrophilic cross-linked polymer matrix or hydrogel to contain the chemo sensing molecules. This not only facilitates PET effect essential for sensing, but also ensures smooth exchange of ions/analytes from water onto the sensor.

[0043] But such a system typically encounters problems when used in complex media such as wastewater or sea water when detecting non-polar targets like NEE. For example, sea water is a complex media with very high concentrations of interfering ions such as calcium (Ca), magnesium (Mg), potassium (K), and/or sodium (Na) ions. The concentrations may be about 100-10000 ppm depending on the water source. Any specific chemo sensing reaction in the presence of such high concentrations of the interfering ions in less likely to happen. This system may be also susceptible to sensor hysteresis, where the sensor performance is not reliable.

[0044] Thus, there is a need for a reliable sensor capable of detecting NFE in complex media such as seawater, wastewater, as well as other types of aqueous media including bodily fluids such as blood.

[0045] In one or more embodiments, a chemosensor overcoming one or more drawbacks listed above is disclosed. The chemosensor is a chemical sensor. The chemosensor is arranged, designed, and/or configured to detect ammonia, NFE, in an aqueous environment including complex aqueous media. The aqueous environment/complex aqueous media may be fresh water, brackish water, sea water, recycled water, reservoir water, wastewater in a water treatment facility or other processing facility such as a meat packing plant, bodily fluid, animal fluid, blood, or the like. [0046] A non-limiting example of the chemosensor is schematically depicted in Fig. 3 A. The chemosensor 100 may include a hydrophobic portion and a hydrophilic portion. The chemosensor may include a hydrophobic matrix or network 102. The matrix 102 may be a cross-linked matrix. The matrix 102 is a selective matrix. The matrix 102 is configured to allow entry of, entrap, enrich, and/or capture NFb species only, while rejecting entry of other hydrophilic species. The matrix 102 is configured to entrap the analyte, sensing molecules, or molecules to be detected, such as NFb. At the same time, the matrix or network 102 is also configured to prevent influx or entry of other compounds such as any other compounds besides the analyte of interest. For example, the matrix or network 102 is configured or structured to prevent entry of any non-ammonia species or compounds into the network 102. The matrix or network 102 may be configured to prevent influx of a sample matrix, that is any other compound besides the analyte in an aqueous sample. The matrix or network 102 may be configured to prevent influx or entry of interfering ions such as Ca, K, Na, or Mg. The matrix 102 further prevents entry of NFF until the NFF is deprotonated. When NFF is deprotonated, the matrix 102 is configured to accept NFb.

[0047] The matrix or network 102 includes hydrophobic material. The matrix 102 may include cross-linked hydrophobic polymer(s). A non-limiting example hydrophobic material may include siloxane-based polymers such as polydimethoxy siloxane, silicone, polybutadiene, polyisoprene, the like, or a combination thereof. The matrix 102 may be a silicone cross-linked matrix.

[0048] The matrix 102 may form or include a cross-linked network 103. The network 103 may include interconnected portions forming gaps 105 between the cross-linked material. The network 103 may form a single layer or be multi-layered. The gaps 105 between individual branches of the network may have the same or different dimensions. The gaps 105 may house other components of the chemosensor 100 such as microparticles 104, chemo sensing molecules 106, surfactant system 108, buffer system 114, co-solvent(s) 118, or a combination thereof.

[0049] The chemosensor 100 includes microparticles 104 with the chemo sensing molecule

106, depicted schematically in Figs. 3A through 3C. The microparticles 104 may be arranged within the matrix 102, in the gaps 105, or both. The microparticles 104 have a smaller diameter than the gaps 105. The microparticles 104 may have the same or different size and/or shape. The microparticles 104 may have a regular, irregular, spherical, or another shape. The microparticles 104 may include the same or different material. The microparticles 104 may include a mixture of different microparticles. The microparticles 104 may include materials such as polymers, silica, cellulose, metal-organic frameworks, the like, or a combination thereof.

[0050] The chemo sensing molecule 106 may include a fluorophore binding site, a fluorophore, a spacer, a receptor, a sidechain, or a combination thereof. The chemo sensing molecule 106/fluorophore may include two or more combined aromatic groups or planar or cyclic molecules with several p bonds. The chemo sensing molecule 106 may include and/or the fluorophore may be anthracene, benzene, carbazole, diphenylfurane, naphthalene, 1,8 naphthalimide, porphyrin, and/or pyrene. The fluorophore is a fluorescent compound configured to re-emit light upon light excitation. The spacer may include a secondary amine adjacent to the fluorophore, a hydrocarbon chain, and/or one or more organic rings. The sidechain may be optional. The sidechain may include one or more ether groups. The receptor may include one or more binding sites for the analyte, one or more ether groups, and/or amine groups. The receptor may form a crown-like structure. The chemo sensing molecule may utilize the PET principle described above. A schematic depiction of the chemo sensing molecule is shown in Fig. 3D while interacting with NFLri.

[0051] The chemo sensing molecule 106 may be coated onto the surface of the microparticles

104. The chemo sensing molecule 106 may be applied and/or covalently linked or bonded onto to the microparticles 104. The chemo sensing molecule 106 may be attached to at least a portion, a portion, or the entire surface of at least some of or all of the microparticles 104. The chemo sensing molecule 106 may be intermixed with the material the microparticles 104 are made from such that the chemo sensing molecule 106 is on the surface and/or in the interior of the microparticles 104.

[0052] The chemosensor 100 further includes a surfactant system 108. The surfactant system

108 may include one or more non-ionic surfactants. Surfactants, including the non-ionic surfactants, include a hydrophilic head group 110 and a hydrophobic tail 112. Non-ionic surfactants are neutral, do not carry an electric charge on their tails. When there is a sufficient amount of surfactant molecules present in a solution, the molecules combine together to form structures called micelles. As the micelle forms in a hydrophobic macro-environment, the surfactant heads position themselves in such a way that they are exposed to water while the tails are grouped together in the center of the structure protected from water.

[0053] The chemosensor 100 includes inverse or reverse micelles as part of the non-ionic surfactant system 108 Reverse micelles are thermodynamically stable assemblies of surfactant molecules organized around a hydrophilic core of water or dissolved solute that spontaneously form optically transparent solutions in low polarity liquids. Reverse micelles are micelles in which the nonpolar and polar phases have reversed their roles and the orientation of surfactant molecules are inverted so that the head groups 110 point into the enclosed volume containing the polar phase. The non-ionic based surfactant system 108 is configured to have stable reverse micelle structures due to its chemical synergy with the matrix or network 102.

[0054] Non-limiting examples of the surfactant may include Triton™ (nonionic surfactant that has a hydrophilic polyethylene oxide chain and an aromatic hydrocarbon lipophilic or hydrophobic group), Polysorbate 20 (polyoxyethylene (20) sorbitan monolaurate), silicone-based surfactants, the like, or a combination thereof.

[0055] The chemosensor 100 may optionally include a buffer or a buffer system 114 The micelles of the non-ionic surfactant have hydrophilic cores 116 The cores 116 may include a buffer. All of the cores, or just a portion of the cores, may include the buffer. The buffer may include one compound, a system of compounds, or a mixture of compounds.

[0056] The buffer may have a relatively low concentration of about a few nM such as 0.5 to 2 nM or 1 nM. The buffer provides conductive environment for the chemo sensing. The core is configured for a high pH of about 8 to 9 and low buffer capacity condition of about 1 to 10 nM by using the appropriate buffer arranged to assist protonation of incoming Mb into Mb⁺ and back to MR when desired.

[0057] The buffer may be arranged to keep the pH of the hydrophilic system close to pKa of

Mb for easy conversion of Mb to Mb⁺. Due to the pH being close to pKa value of ammonia, the buffer helps maintain chemical dynamic equilibrium between NHG inside micelles and NEE outside in the hydrophobic matrix phase.

[0058] Non-limiting examples of the buffer may include Tris buffer

(tris(hydroxymethyl)aminomethane), HEPES (2-[4-(2-hydroxyethyl)piperazin- 1 -yl]ethanesulfonic acid), PBS (phosphate-buffered saline), the like, or a combination thereof.

[0059] The chemosensor 100 may optionally include a compound configured to tune the dissociation constant K_d of NEE⁺ binding at lower or higher concentration range. The compound may be a solvent, herein also referred to as a co-solvent. The term co-solvent is being used because the media or sample to be tested includes water, which is a solvent. The term co-solvent thus distinguishes between the water included in the tested media/sample and the compound configured to tune the dissociation constant. Since the tested medium is an aqueous medium, the aqueous medium may enclose the chemosensor when the chemosensor is submerged or otherwise put in contact with the medium. The medium may intermix with one or more liquid portions of the chemosensor.

[0060] The co-solvent 118 may be present in the core(s) of the reverse micelles of the non ionic surfactant. The co-solvent may be configured to tune the dissociation constant of NH4⁺ binding at lower or higher concentration range. The co-solvent thus chemically tunes the dissociation constant, Kd, which controls the binding energy between the analyte (NEE) and the binding site of the chemosensor. The co-solvent thus chemically tunes the overall sensitivity range of an analyte detection.

[0061] The dissociation constant K_d is related to the binding energy by the relationship:

[0062] K_d=coe^AG/kT,

[0063] where co is the standard reference concentration (1 molar),

[0064] AG is the binding free energy (typically negative), and

[0065] kT is the temperature in energy units. [0066] Therefore, a tighter binding reduces AG (more negative), and lowers the dissociation constant, leading to higher sensitivity. The binding free energy equals the free energy of the bound state minus the free energy of the unbound (solvated) state. Because of the ion charge, the solvation energy strongly depends on the solvent dielectric properties, i.e. the electrostatic interaction between the solvent and the charged ion. This changes with the co-solvent, allowing the co-solvent(s) to be used as a tuning knob for the binding energy and thus the sensitivity.

[0067] A non-limiting example of the co-solvent(s) may include glycerol, ethylene glycol, sucrose, polyacrylic acid, polyvinyl alcohol, the like, or a combination thereof.

[0068] The chemosensor may include a mixture of the buffer system and the co-solvent(s). In another embodiment, the chemosensor may be free of the buffer system, but include the co-solvent(s). In another embodiment, the chemosensor may be free of the co-solvent(s), but include the buffer system. In yet another embodiment, the chemosensor may be free of the buffer system and the co- solvents).

[0069] Typically, a chemosensor molecule is designed and synthesised to cater to the analyte measurement range. This approach is impractical because electronic potentials of different chemicals used in sensor fabrication will influence the overall performance of the sensor in the given set of conditions. To overcome this disadvantage, the herein-disclosed chemosensor may include both the buffer and the co-solvent(s). The buffer and the co-solvent(s) may form a mixture.

[0070] The resultant chemosensor is configured to facilitate 1) hydrophilic environment required for PET effect and thus chemo sensing, 2) dynamic equilibrium condition between NEE and NH ⁺, and/or 3) tuning of the measurement range of NEE detection as per requirement without changing basic chemical architecture of NEE⁺-specific chemosensor molecule.

[0071] In the chemosensor disclosed herein, the reverse micelles may enclose the microparticles 104 All, some, or at least one of the microparticles 104 may be enclosed by or trapped in a reverse micelle of the surfactant system 108 The surfactant reverse micelle heads may be oriented towards the core 116 including the microparticle 104 The matrix 102 may form a base for the microparticles 104, and the surfactant system 108 may envelop, surround, or enclose the individual microparticles 104 within the matrix 102. As a result, as the NH3 from the tested medium encounters the chemosensor structure, enters the reverse micelle, gets protonated into NH4, and reacts with the chemo sensing molecule 106 present on the microparticle 104. Fluorescence of the chemo sensing molecule 106, caused by the interaction of the chemo sensing molecule 106 with the analyte, then indicates presence of NFb in the tested medium, upon light excitation.

[0072] As the chemosensor 102 interacts with the tested media, named herein such as sea water, wastewater, blood, etc ., the chemosensor 102 may include water as a solvent present in the tested media.

[0073] The chemosensor 102 may be incorporated within a more complex structure. A non limiting example of the structure 150 is shown in Fig. 4. As can be seen in Fig, 3, the chemosensor 102 may be a part of a multi-layer structure or film 150. The chemosensor 102 may form a top layer 120 which is adhered to a transparent substrate 122. Adhesion may be provided via an adhesive layer 124. The chemosensor 102 may include a layer having a black tint such as carbon black to prevent incidences of random, unexpected sensor-light interaction coming from ambient light.

[0074] The ammonium may be removed from the reverse micelle environment through chemical dynamic equilibrium by adjusting the concentration of NFb inside the micelle and outside, within the hydrophobic matrix phase to reset the chemosensor 100. A desired reset may be also accomplished by applying a pH increase to drive the MTi⁺ -> MH + H⁺ reaction. The pH increase may be applied through an electrochemical component such as by applying a voltage, injecting a buffer solution, or adding other solutes.

[0075] The chemosensor described herein may be prepared by the following method. The microparticles with the covalently linked chemosensor molecules may be added into a container such as a glass bottle, followed by an optional addition of the co-solvent(s) and/or the buffer system. The mixture may be stirred well with a stirrer such as a magnetic stirrer for a first time period. The first time period may be, for example, about 15 minutes to 1 hour, 20 minutes to 45 minutes, or 30 to 40 minutes. The mixing may be followed by addition of hydrophobic matrix phase precursor to the solution and continued stirring of the suspension for a second time period. The second time period may be about 30 minutes to 5 hours, 1 hour to 4 hours, or 2 to 3 hours. Subsequently, the non-ionic surfactant system may be added. The addition may be accomplished, for example, by dissolving the surfactant(s) in a small amount of an organic compound such as ethyl acetate. The mixture or dispersion including the solvent may be stirred for a third time period. The third time period may be about 5 to 30 minutes, 10 to 25 minutes, or 15 to 20 minutes. Subsequently, a cross-linker and a small amount of inhibitor may be added. The dispersion may be stirred for a fourth time period. The fourth time period may be about 30 minutes to 3 hours, 45 minutes to 2 hours, or 1 to 1.5 hours. Subsequently, a catalyst may be added, and the mixture may be stirred for a fifth time period. The fifth time period may be about 2 to 10 minutes, 5 to 7 minutes, or 3 to 6 minutes. Afterwards, the dispersion may be cast onto a film to form a chemosensor layer. The film may be a transparent film such as a transparent PET layer. The casting may be performed with a knife coater or another suitable tool. The fabricated chemosensor layer may be stored for a sixth time period to achieve complete or substantially complete polymerization of the matrix phase. The sixth time period may be, for example, about 6 to 18 hours, 10 to 15 hours, or 12 to 14 hours. The storing may be provided under ambient conditions such as ambient temperature and humidity.

[0076] Among the advantages of the herein-described chemosensor is the ability of real-time measurement. “Real-time” relates to the capability of measurement or analysis which takes place and the results are available virtually immediately or in a very short period of time after the measurement or analysis takes place. A real-time sensor, device, or system, described herein, has the advantage of providing results at the measurement location in a very short period of time. Real-time may relate to several second to several minutes.

[0077] Additionally, typical crown ether-based sensor molecules without the presence of co- solvents) would typically engage in binding reaction in the range of about 50-100 ppm NELf due to Kd of 80 ppm of the sensor molecule. The herein-disclosed chemosensor facilitates hydrophilic environment that is essential for PET effect and ensures shifting of measurement range down to about 0-5 ppm without structural changes to the chemo sensing molecule. The resulting measurement range is thus much lower. [0078] While the chemosensor 100 described herein has been focused on detection of ammonia, the principles of the chemosensor 100 may be applied to different analytes of interest. The chemosensor including the hydrophobic matrix 102 housing the microparticles 104 including the sensing molecule 106, further including the surfactant system 108, and optionally the buffer system 114 and/or co-solvent 118 may be applicable for detection, measuring, and/or monitoring of various analytes in the media described herein. The chemistry of the chemosensor 100, or its portions, may differ from that described herein based on the type of aqueous media, sample, analyte. Non-limiting example analytes to be detected by the chemosensor described herein may include toxic ions such as Pb, As, Cd, Cr; ions that create “hard water” such as Mg and Ca; sulphuric compounds such as ThS and H2SO4; carbonic compounds such as CO2 and formic acid (HCOOH).

[0079] The analyte may be a part of an aqueous media or an aqueous sample. The term

“sample” is used broadly including a small quantity intended to show what the whole of a tested medium is like as well as a larger volume of the tested medium. The sample includes the analyte and the remainder of the sample also called a sample matrix. The chemosensor disclosed herein is configured or structured to allow access of the analyte to the chemosensing molecules, but prevent entry of the sample matrix to the chemosensing molecules.

[0080] Various samples including the analyte of interest may differ from one another due to the environment the samples come from. For example, individual samples may differ from one another by their biological, biochemical, chemical, and/or physical properties such as pH, temperature, alkalinity, suspended solids, salinity, dissolved gasses, etc.

[0081] In a non-limiting example, the analyte may be an aquacultural analyte or an analyte present in an aquacultural sample. The analyte is to be detected by an aquacultural fluorescence-based chemosensor described herein. The aquacultural sample may originate from an aquacultural environment or media such as aquafarming of fish, crustaceans, molluscs, or the like. As such, the aquacultural sample may contain biological, biochemical, chemical, and/or physical portions typical for the aquacultural farming. The biological portion may include presence of plankton, fish waste, uneaten food. The chemical portion may include pH between about 6.5 and 9.0 if the aquacultural site is healthy or a different pH if the site pH needs to be improved, dissolved gasses such as oxygen, carbon dioxide, nitrogen, ammonia, dissolved oxygen of at least 5 ppm, content of CO2 of about 0 ppm to 5-15 ppm for healthy aquafarming. The physical portion may include clay particles as suspended solids, or the like.

[0082] In another non-limiting example, the analyte may be a farming environment analyte or an analyte in a farming environment sample. The farming environment sample may be a sample originating from an aqueous media at a farm location. The farming environment sample may be a sample from an agricultural runoff or a sample from a water source used as a drinking water for the animals at the farm. The farm may be a location cultivating livestock such as cattle, sheep, horses, goats, poultry such as chickens, geese, ducks, turkeys, pigs, horses, or other animals. The farming environment sample may contain biological, biochemical, chemical, and/or physical portions typical for farming on land including agricultural contaminants. The agricultural contaminants may include nutrients such as nitrogen, phosphorus, pesticides, herbicides, insecticides, fungicides, ammonia, bacteria, and the like.

[0083] The analyte may be a manufacturing analyte or an analyte present in a manufacturing sample. The manufacturing sample may include biological, biochemical, chemical, and/or physical portion typical for a specific manufacturing process conducted at a facility such as a factory. An example facility may be a meat packing plant or a slaughterhouse. The contaminants may include nitrate, nitrite, ammonia, fecal coliform, biproducts of the disinfection processes such as chlorine, etc.

[0084] The analyte may be a wastewater analyte or an analyte present in a wastewater sample.

The wastewater sample may be an industrial or domestic wastewater sample. The wastewater sample may include biological, biochemical, chemical, and/or physical portion typical for wastewater including, but not limited to, organic substances and sulphide compounds. A wastewater sample from petroleum industry may include petroleum, fuel oil, etc. A wastewater sample from chemical plants may include carbonates, hydroxides, sand, organic compounds, salts of acids such as sulfuric acid or hydrochloric acid. A wastewater sample may originate from washing of equipment or surfaces and include acids, ammonia, fluorides, nitrites, methenamine, sulphates, arsenic, vanadium, etc. [0085] The analyte may be a drinking water analyte or an analyte present in a drinking water sample. The drinking water sample may include a fresh water or reservoir water sample for human or animal consumption. The drinking water sample may include biological, biochemical, chemical, and/or physical portion typical for drinking water such as microbes, toxins produced by bacteria, nitrogen, salts, ammonia, pesticides, metals, drug components, etc.

[0086] The analyte may be a bodily fluid analyte or an analyte present in a bodily fluid. An example bodily fluid sample may be blood, plasma, urine, sweat, saliva, mucus, etc. The bodily fluid sample may originate in a human or an animal. The bodily fluid sample may include biological, biochemical, chemical, and/or physical portion typical for individual bodily fluid, including water, salts, protein such as enzymes like amylase, ammonia, sugars, urea, uric acid, red blood cells, white blood cells, platelets, electrolytes such as potassium, phosphorus, etc.

[0087] The analyte may be an aqueous analyte from an aqueous media to be reprocessed or which was reprocessed or converted for further use or an analyte from a sample including the same. The reprocessing sample may include a recycled water sample, brackish water sample, or sea water sample.

[0088] The chemosensor may be used for indication of ammonia, measuring of NTk/NTfri content, and/or monitoring in various environments. The chemosensor may be used for real-time indication of ammonia in various aqueous media including fresh water, brackish water, sea water, recycled water, reservoir water, wastewater in a water treatment facility or processing facility, bodily fluid, animal fluid, blood, or the like. The chemosensor may be used in aquaculture such as farming of fish such as salmon, trout, crustaceans such as shrimp, lobster, crabs, crayfish, molluscs such as clams, oysters, mussels, scallops, the like, or a combination thereof. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish. The chemosensor may be used for indication and/or monitoring of the aquatic health of a reservoir. The chemosensor may be also used for detection of ammonia in drinking water, wastewater, treatment water, sewage, household wastewater, municipal water sources. The chemosensor may be used in agriculture such as animal farming. The chemosensor may be used in industrial environments such as chemical plants, farm animal processing plants, or the like.

[0089] EXAMPLE

[0090] An ammonia chemosensor made by the method described above, and including tris buffer and glycerol co-solvent, was tested in a titration experiment using sea water as the aqueous medium. The results of the real-time NEE sensing in sea water in 0-5 ppm concentration range is shown in Fig. 5. As can be seen, Fig. 5 shows an increasing linear trend in the range of 0-5 ppm range.

[0091] In another embodiment, the chemosensor 100 may be incorporated into a device configured to detect the analyte. The device may be an optical device or optical system.

[0092] Typically, optical systems designed to identify analytes include complicated arrangements, but are faced with many drawbacks. For example, many optical systems struggle with providing and preserving a sufficient amount of light, a strong enough signal for detection, and loss of sensitivity.

[0093] Among the optical systems are optical chemosensor systems, for example utilizing fluorescence. A fluorescence-based sensing of an analyte requires a minimum irradiance with a maximum signal which is as strong and non-noisy as possible. If the irradiance of the input light is too strong, it contributes to degradation of the chemosensor. The irradiance may photobleach the molecules by creating unwanted side reactions that damage the ability of the molecules to fluoresce. Additionally, hydrolysis or chemical stress may cause a failure resulting in degradation of the sensor phase from the film. As a result, the sensor molecules or microparticles may detach from the sensing layer, reducing overall concentration of the sensing molecules in the light path and decreasing the output signal and damaging the calibration.

[0094] Some of the optical systems try to overcome drawbacks by introducing signal strengthening items such as fiber optic cables for signal multiplication. Other systems may incorporate multiple detectors. Some of the systems also implement waveguides for light transmission. All of these items make the traditional systems more complex, expensive, and sensitive to transportation. As a result, the optical systems are quite large in dimensions and traditionally stationary.

[0095] Yet, there is a need for an optical analytical detection system which is relatively inexpensive, portable, and capable to withstand various environments including corrosive environment associated with the tested aqueous media.

[0096] In one or more embodiments, an analytical optical detection system is disclosed. The system may be designed as a portable or point-of-use system. The terms portable and point-of-use relate to the system which is not bound to a single location such as a laboratory, a system which does not need to be secured to a table or another working surface in a laboratory, building, or a vehicle, a system which may be carried to a testing site and used at the site. The portable or point-of-use system may be easily transported from one location to another. The portability makes the system suitable for various applications and locations. The portability further allows faster and more economical analyses than traditional systems because an analysis may be conducted at the location where results are needed instead of transportation of samples to a lab.

[0097] The portable system is designed to analyze one or more analytes. An example analyte may include ammonia. Other analytes, especially those named above, are contemplated. The system may thus be an ammonia analytical system. Non-limiting examples of the system 200, 200’ are shown in Figs. 6 and 7. The system 200, 200’ may be incorporated into a device, non-limiting example of which is shown in Figs. 8 and 9.

[0098] Based on the type of analyte and sample, the optical system and sensing device disclosed herein may include structural differences to reflect the environment the optical system and sensing device would be used in. For example, the housing for the aquacultural chemosensor and sensing device for the aquacultural environment/analyte would be made to withstand the aquacultural environment. An example of such features may include a water-proof, anti-corrosive housing, and/or seals, gaskets preventing seawater ingress into the optical system. [0099] The optical system 200, depicted in Fig. 7, includes a source of light 202. The light source 202 may be an LED such as a blue LED, laser, modulatable lamp, or modulatable light device. The light source 202 may be a modulated LED light source 202. The light source 202 may be a direct optical modulator. The light source 202 emits light having a wavelength depending on or in response to the excitation wavelength of the chemosensor included in the system 200. A non-limiting example wavelength may be about 450 to 490, 460 to 480, or 470 to 475 nm. Other wavelengths are contemplated. The wavelength emitted by the light source 202 may be a first wavelength. The light source 202 may be a monochromatic light source. The light source 202 may be an excitation source. The light source 202 is modulated at a certain frequency (f_m) which causes intensity of the excitation light to be modulated. The modulated excitation intensity gives rise to emissions at the chemosensor that are modulated at the same frequency (fm). The modulated light source 202 generates a beam of light carried over free space. The light is thus not propagated through an optical waveguide such as optical fibres.

[0100] The system 200 further includes a lens 204. The lens 204 may be a collimating lens or a collimator. Collimating is the process of accurately aligning light or particles in a parallel fashion. A collimating lens 204 may ensure that the incoming light has minimal spread as it propagates. The lens 204 may be an aspheric condenser lens. The lens 204 may include a diffuser. The lens 204 is configured to collimate and/or diffuse the light from the light source 202. The lens 204 collimates the light beam to maximize the beam diameter of the excitation light on the chemosensor included in the system 200. The lens 204 is arranged downstream from the light source 202. The lens 204 may be located adjacent to the light source 202.

[0101] The system 200 may further include one or more filters. The one or more filters may be colored filters. An example filter may be a first filter 206. The first filter 206 may be an excitation filter. The excitation filter 206 may limit the irradiance to the spectroscopic window that causes florescence. The filter 206 may be placed downstream from the lens 204 and the light source 202. The filter 206 is arranged between the lens 204 and the mirror 208. In one or more embodiments, the filter 206 is omitted. [0102] Following the lens 204 and/or the filter 206, the system 200 includes a mirror 208. The mirror may be a dichroic mirror. The mirror 208 may be a high or long pass dichroic mirror or beam splitter. A dichroic mirror allows a light of certain wavelength(s) to pass through while light of other wavelength(s) is reflected.

[0103] After passing through the lens 204 and/or the excitation filter 206, the excitation light is directed to the dichroic mirror 208. The light is reflected at an angle downward to the chemosensor 210. The reflection angle may be 45 degrees. The chemosensor 210 may be the chemosensor 100 described above and shown in Figs. 3 A-4.

[0104] The chemosensor 210 may be applied onto a film or layer(s). The film or layer(s) may include a dark portion, for example including carbon black, or a layer to prevent ambient light from entering the optical system 200. The film or layer(s) may allow ingress of water to the chemo sensing portion of the chemosensor 210. The chemosensor 210 is in contact with the liquid media to be analyzed. The chemosensor 210 reacts with the media, and if the analyte is present in the media, the chemosensor 210 causes fluorescence as the chemo sensing molecule reacts with the analyte. The chemosensor 210 may give rise to fluorescence in proportion to the concentration of the analyte in the media.

[0105] Fluorescence generated by the chemosensor has a different wavelength than the excitation light which arrived at the chemosensor via reflection at the mirror 208. The excitation wavelength is thus very different from the detection wavelength. Fluorescence is thus not reflected by the dichroic mirror 208, but instead, fluorescence passes through the dichroic mirror 208 as it travels upward and is transmitted through the dichroic mirror 208 into a detection/photodetection portion 212 of the system 200. An example detection wavelength may be about 520 to 550 nm, 525 to 545, or 530 to 535 nm. Other wavelengths are contemplated. Fluorescence may be a light having a second wavelength. The second wavelength is different from the first wavelength.

[0106] The detection portion 212 may include a second filter 214. The second filter 214 may be an emission filter configured to reject any excitation light. The second filter 214 may be a detection filter. The detection filter may limit the detection of the excitation signal, reduce noise, or both. The filter 206 may be located between the mirror 208 and the second lens 216.

[0107] The system 200 includes a second lens 216. The lens 216 may be an asymmetric lens.

The second lens 216 may be a plano-convex lens. A plano-convex lens is flat on one side and outward- curved on the other side. A plano-convex lens is configured to focus parallel rays of light to a single point. The lens 216 may collect the light. The lens 216 may focus the fluorescent light onto a photodetector 218. The lens 216 is located upstream from the filter 206, the mirror 208, and downstream from the photodetector 218.

[0108] The photodetector 218 is configured to convert light photons into current. The photodetector 218 may be a photodiode or a phototransistor. The photodiode is a semiconductor device that converts light into an electrical current. The current is generated when photons are absorbed in the photodiode. The phototransistor is a semiconductor device configured to sense light levels and alter the current flowing between an emitter and a collector according to the level of light it receives. The photodetector 218 may include one or more optical filters, built-in lenses, or the like. The system 200 may include a single photodetector 218.

[0109] The system 200’ shown in Fig. 7 may include the same components as the system 200, but further includes an electrical device or an electronic system 220. The electrical device 220 may include one or more controllers. The electrical device 220 may be a printed circuit board (PCB) 220. The electrical device 220 may include one or more microprocessors enabling data processing, signal amplification, a timing circuit, electrical or electronic components, conductive tracks, conductive pads, data register, and/or other parts.

[0110] The electrical device 220 is configured or programmed to control the light source 202, receive input such as detect signal from the photodetector 218 and/or the photodetection portion 212, provide input to one or more portions of the system 200, provide output to another device, or a combination thereof. The input the electrical device provides to the light source 202 may include a command to initiate analysis, stop the analysis, initiate excitation of light, stop excitation of light, the like, or a combination thereof. The input the electrical device may receive from the photodetector 218 may include a signal. The output the electrical device provides may be a number and/or data associated with the analyte, its quantity, or other information related to the analysis.

[0111] The system 200 and/or 200’ may also include one or more additional devices such as a differential amplifier, high pass filter, or the like. The additional devices may filter out the DC and low frequency component of light. The additional devices may allow only the modulated, high frequency emissions to pass through and be amplified. This ensures that any ambient light or stray light picked up by the photodetector is not amplified. This leads to an improvement in the signal to noise ratio of the fluorescence signal generated by the chemosensor 210.

[0112] The system 200 and/or 200’ may be compatible with various devices and systems. For example, the system may be compatible with a computer and include a converter pluggable into one or more devices including a computer. The system may be wired or wireless, utilizing communication via Bluetooth, WiFi, Zigby, GSM, RFID, or another form of communication to transmit the signal out of the system 200, 200’.

[0113] The system disclosed herein may be incorporated in a housing. A non-limiting example of the housing is schematically shown in Fig. 7. An alternative view of the housing is shown in Fig. 8. The housing 250, the system 200 and/or 200’, and additional items disclosed herein, may form an analytical or sensing device 300.

[0114] The housing 250 may be compact, allowing for portability of the analytical device 300.

The housing 250 may be modulated, molded, injected, extruded, 3D-printed, or otherwise formed around one or more components of the device 300. The housing 250 is designed to carry, protect, or enclose the optical and electrical components of the device system 200 and/or 200’ and the device 300.

[0115] The housing 250 may have one or more layers. For example, the housing 250 may have a first or inner layer 252 enclosing the system 200’, including or excluding the electrical device 220. The first layer 252 may form an inner portion or layer of the housing 250. The housing 250 may also include an outer layer 254 enclosing all internal components, including the system 200’ having the optical components and the electrical device 220 together. The optical components and the electrical device may be mounted or otherwise attached in the housing 250. The attachment may be permanent or temporary, allowing for an exchange of components.

[0116] The outer layer 254 may be waterproof and corrosion resistant. The waterproof feature makes the system 200, 200’, and/or device 300 submersible in an aquatic medium. For example, the outer layer 254 may be made from a corrosion-resistant and water-resistant material. Alternatively, a coating having the desired qualities may be applied onto the outer layer 254. A non-limiting example coating may be a hydrophobic coating. The outer layer 254 and the housing 250 may be water-resistant according to IP67, referring to the Ingress Protection Code, sometimes referred to as International Protection Code, IEC standard 60529 which classifies and rates the degree of protection provided by mechanical casings and electrical enclosures against intrusion, dust, accidental contact, and water. The IP67 rating means that the device disclosed herein can be dropped into a body of water up to a meter deep for half an hour without any changes to the function or durability of the device.

[0117] While the first layer 254, the housing 250, or both include the optical components of the system 200 or 200’, the chemosensor 210 is housed separately. The housing 250 is waterproof, protecting the optical and electrical components while the chemosensor 210 has access to the medium to be tested. The waterproof feature makes the system 200, 200’, and/or device 300 submersible in an aquatic medium.

[0118] The chemosensor 210 may be placed in a compartment 260. The compartment 260 may be a barrel, pocket, cylinder, receptable, vessel, enclosure, or a container attached or attachable to the housing 250. The connection between the housing 250 and the compartment 260 is such that the integrity and water-proof quality of the housing and its internal components is not compromised. The connection may include one or more sealing components 262 ensuring water-tight seal, for example one or more O-rings, gaskets, or a combination thereof. A non-limiting example of the compartment 260 is shown in Fig. 9.

[0119] The compartment 260 may have an upper portion 266 and a lower portion 268. The upper portion 266 may be attachable, permanently or temporarily, to the housing 250, and to the lower portion 268. The upper portion 266 may house the sealing component(s) 262 and the chemosensor 210. The lower portion 268 is attachable to the upper portion 266. The lower portion 268 may have an opening and closing mechanism 270 allowing for ingress of the tested medium into the device. The mechanism 270 may feature, for example, one or more slidable portions 272.

[0120] The housing 250, the first layer 252, the second layer 254, the compartment 260, or a combination thereof may be made from the same or different material. For example, the material may include steel such as stainless steel, plastic such as thermoplastic or thermoset, composite material, ceramic, or a combination thereof. The housing 250, the first layer 252, or both may be black in color.

[0121] As can be also seen in Fig. 8, a lead/plug 222 from the electrical device 220 may extend from the housing 250 to accommodate wires such as a data cable.

[0122] The device and the system disclosed herein may be free from fiber optic cable(s), waveguide(s), secondary detector(s), and/or one or more objective(s) configured to focus the light. The system, and thus the device, are thus less complex than traditional systems, more economical, and may be incorporated into devices of smaller dimensions than traditional optical analytical systems. Without limiting the disclosure to a certain range of dimensions, the device and other devices in which the system may be employed, may have such dimensions that the device may be portable and/or handheld.

[0123] The system and the device disclosed herein may be used as an analytical optical instrument for complex media named above in environments named above for identification, monitoring, quantitative and/or qualitative analysis of analytes named herein.

[0124] In one or more embodiments, a method of using the disclosed chemosensor, system, and device is disclosed. The method may include bringing the chemosensor in contact with the media/sample to be tested. Upon contact with the media/sample, the chemosensor may prevent influx of one or more types of interfering ions. The method may include allowing influx of the analyte to the matrix such that microparticles, embedded in the matrix, carrying the chemo sensing molecules with the surfactant system may react with the analyte, generating fluorescence, upon light excitation. [0125] The method may include initiating excitation from the light source. The method may include passing the light beam via free space. The method may include passing the light beam via a lens and/or a first filter. The method may include reflecting the light via a mirror such as a dichroic mirror onto the chemosensor.

[0126] The method may also include generating fluorescence via the reaction of the analyte with the chemo sensing molecule. The method may include transmitting the fluorescent light via the mirror, a second filter, and a second lens to a photodetector. The method may also include converting the light photons in the photodetector into electrical current or signal.

[0127] The method may further include modulating, collimating, reflecting, transmitting, filtering, rejecting, and/or focusing the excitation or fluorescent light, reducing noise via one or more items of the disclosed system, or a combination thereof.

[0128] The method may also include forwarding or transmitting the electrical signal into another device via an electrical device, electronic system, or wirelessly. The method may include controlling the optical system and/or the device via the electrical device. The method may include controlling or commanding the source of light and/or one or more items of the system and/or device via the electrical device. The method may include transmitting the electrical signal wirelessly or via one or more wires into a different device, system, or a database.

[0129] The processes, methods, or algorithms disclosed herein may be deliverable to or implemented by a processing device, controller, or computer, which may include any existing programmable electronic control unit or dedicated electronic control unit. Similarly, the processes, methods, or algorithms may be stored as data and instructions executable by a controller or computer in many forms including, but not limited to, information permanently stored on non-writable storage media such as ROM devices and information alterably stored on writeable storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media. The processes, methods, or algorithms may also be implemented in a software executable object. Alternatively, the processes, methods, or algorithms may be embodied in whole or in part using suitable hardware components, such as Application Specific Integrated Circuits (ASICs), Field- Programmable Gate Arrays (FPGAs), state machines, controllers or other hardware components or devices, or a combination of hardware, software and firmware components.

[0130] The following application is related to present applications: U.S. Pat. Appl. Ser. Nos.

_ (RBPA 0327 PCT, RBPA 0329 PCT, and RBPA 0330 PCT), filed on February

10, 2021, which are incorporated by reference in their entirety herein.

[0131] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the disclosure that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.

Claims

WHAT IS CLAIMED IS:

1. An optical system comprising: a fluorescence-based chemosensor configured to emit fluorescence upon reaction of a chemo sensing molecule with an aquacultural analyte and upon light excitation; a source of modulated light configured to generate a beam of light having a wavelength in response to an excitation wavelength of the chemosensor, the light being carried over free space; a collimating lens configured to collimate and diffuse the modulated light; a dichroic mirror arranged to reflect the modulated light onto the chemosensor and transmit re-emitted light from the chemosensor onto a photodetector; and a lens located upstream from the photodetector configured to focus the re emitted light onto the photodetector, the optical system being enclosed in a waterproof, corrosion-resistant housing.

2. The optical system of claim 1, wherein the aquacultural analyte is ammonia.

3. The optical system of claim 1, wherein the optical system is a real-time analytical sensor.

4. The optical system of claim 1, wherein the lens is an asymmetric lens configured to focus the re-emitted light before the re-emitted light enters the photodetector.

5. The optical system of claim 1, further comprising one or more colored filters.

6. The optical system of claim 1, wherein the optical system is housed in a portable aquacultural aqueous media sensing device.

7. A real-time ammonia sensing device for aquacultural aqueous media, comprising: an optical system having a source of light configured to generate a beam of light having a first wavelength to be carried over free space; a collimator configured to collimate the light, a dichroic mirror configured to reflect the collimated light at the first wavelength onto a fluorophore-containing chemosensor configured to react with an analyte within an aquacultural aqueous media sample and transmit a light re-emitted from the chemosensor having a second wavelength onto a photodetector; and an electronic system having a microprocessor programmed to receive a signal corresponding to the re-emitted light from the photodetector and to provide information based on the signal in real-time.

8. The sensing device of claim 7, wherein the first wavelength is an excitation wavelength of the chemosensor.

9. The sensing device of claim 7, wherein the second wavelength is different from the first wavelength.

10. The sensing device of claim 7, wherein the optical system and the electronic system are sealed from contact with the aquacultural aqueous media.

11. The sensing device of claim 7, wherein the device is portable.

12. The sensing device of claim 7, wherein the device includes a waterproof, corrosion resistant housing.

13. The sensing device of claim 7, wherein the chemosensor is housed in a compartment accessible by the aquacultural aqueous media.

14. An aquacultural media ammonia sensing device comprising: a housing including a source of modulated light configured to generate a beam of light having a first wavelength depending on an excitation wavelength of a fluorescence-based chemosensor, the light being carried over free space; a collimating lens configured to collimate and diffuse the modulated light; a dichroic mirror configured to reflect the modulated light onto the chemosensor and transmit re-emitted light from the chemosensor onto a photodetector; and a lens located upstream from the photodetector configured to focus the re-emitted light onto the photodetector; and a compartment attached to the housing and including the fluorescence-based chemosensor configured to re-emit the light upon reaction of a chemo sensing molecule with ammonia in an aquacultural aqueous media sample.

15. The device of claim 14, wherein the housing is waterproof and corrosion resistant.

16. The device of claim 14, wherein the compartment is configured to enable contact of the chemosensor with the aquacultural aqueous media.

17. The device of claim 14, wherein the housing further comprises an electronic system including a microprocessor programmed to receive a signal from the photodetector.

18. The device of claim 17, wherein the microprocessor is programmed to communicate with another electronic device.

19. The device of claim 14, wherein the device is a portable device.

20. The device of claim 14, wherein the device is a real-time aquacultural ammonia sensor.