Optical sensor for detecting beryllium ions and / or measuring beryllium ion concentration

Abstract

The invention relates to an optical sensor for detecting beryllium ions and / or measuring the concentration of beryllium ions in a fluid medium, comprising a resonant structure (1), the surface of which is covered by a layer (2) of a macrocyclic compound. The invention also relates to a method for covering the surface of a resonant structure (1) of an optical sensor with a layer (2) of a macrocyclic compound such that said optical sensor can detect beryllium ions and / or measure the concentration of beryllium ions in a fluid medium.

Description

Technical Field

[0001] The present invention relates to optical sensors for detecting beryllium ions and / or measuring beryllium ion concentrations, and methods for enabling optical sensors to perform said functions. Background Art

[0002] Beryllium ("Be") is an alkali metal that is indispensable in various high-tech industries, such as automobile manufacturing, aerospace, nuclear energy, electronics and communications. Contrary to the utility provided by Be, it is classified as a Class A carcinogen and is known to be one of the most toxic elements that is extremely harmful to human health. With the prosperity of the above-mentioned industries, more and more workers in the industry or civilians living nearby are exposed to the dangers of Be. This exposure may occur during the manufacture, production or disposal of waste, leading to chronic beryllium disease (CBD), acute clinical pneumonia, and lung or bone cancer. Therefore, it is necessary to detect Be and remove it from the environment where it is disposed.

[0003] Various techniques have been introduced for the detection of Be. These techniques include gas spectroscopy, atomic absorption spectroscopy ("AAS"), inductively coupled plasma mass spectrometry ("ICP-MS"), and inductively coupled plasma atomic emission spectroscopy ("ICP-AES"). However, the above techniques have many disadvantages, including the need for very expensive instrumentation and the need for relatively long times to complete. The disadvantages further hinder the use of this technique for on-site, in-situ detection and measurement of Be.

[0004] In patent application CN104003370A, a method for preparing a fluorescent carbon quantum dot probe for detecting beryllium in water is disclosed. In addition to fluorescent carbon quantum dots, macrocyclic compounds are known to bind metal cations in contaminated media. However, it is difficult to apply specific macrocyclic compounds on test structures, especially on compact test structures that can be used to detect Be and measure Be concentration in an on-site, in-situ manner. Summary of the invention

[0005] The above-mentioned disadvantages and difficulties are overcome by the present invention as described in detail in the following paragraphs.

[0006] One aspect of the present invention provides an optical sensor for detecting beryllium ions and / or measuring the concentration of beryllium ions in a fluid medium, comprising a resonant structure, at least a portion of the surface of the resonant structure being covered by a layer of a macrocyclic compound, characterized in that the macrocyclic compound is diamino-benzo-9-crown-3, and its material index varies depending on the amount of beryllium ions bound thereby.

[0007] Advantageously, diamino-benzo-9-crown-3 is an ionophore capable of chemically binding to beryllium ions in the medium, allowing the corresponding change in the material index to be detected and / or measured.

[0008] Advantageously, the resonant wavelength of the resonant structure shifts according to a change in the material index.

[0009] In one embodiment, the resonant structure comprises a test waveguide and a reference waveguide, the test waveguide being exposed to the medium and the reference waveguide being sealed from any contact with the medium. Typically, the resonant structure is formed in silicon or silicon dioxide.

[0010] In one embodiment, the light source is configured to emit light of at least one wavelength, the light is directed through the test waveguide and the reference waveguide, and a shift in the resonant wavelength is determined by comparing the patterns generated from the respective test waveguide and reference waveguide, the shift corresponding to the concentration of beryllium ions in the medium. Advantageously, the comparison allows accurate measurement of shifts of <500 pm, enabling sensitivities as low as 10 ppb beryllium ions to be achieved.

[0011] In yet another embodiment, the optical sensor further comprises a spectral interrogator connected to the outputs of the test waveguide and the reference waveguide, capable of providing a reading of the wavelength or phase of the light.

[0012] Typically, the test waveguide and reference waveguide each have a width of 15-1000 nm and a length of 200 μm to 1 cm.

[0013] Typically, the light source comprises at least one laser source and is capable of emitting light in the wavelength range from 1500 to 1600 nm. Typically, the laser source is capable of scanning and emitting light in the aforementioned wavelength range in less than one second.

[0014] Typically, during testing, the exposable resonant structure is exposed to the medium for a time interval of 30 seconds to 2 minutes.

[0015] In yet another embodiment, the optical sensor further comprises a pair of multimode interferometers, wherein one multimode interferometer is connected to the input end of the resonant structure for diverging light, and the other multimode interferometer is connected to the output end of the resonant structure for converging light.

[0016] In yet another embodiment, the optical sensor further comprises: a silicon slab interposer and a spot size converter connected to the multimode interferometer at the input end; and a waveguide having its input connected to the light source and its output connected to the silicon slab interposer.

[0017] In yet another embodiment, the spectral interrogator includes: a pair of multi-mode interferometer-based reflectors and two pairs of micro-ring resonators.

[0018] Typically, when the macrocyclic compound is exposed to a medium having a combination of different metal ions, the resonant wavelength of the resonant structure shifts over time.

[0019] Typically, the shift in resonant wavelength is a superposition of resonant wavelength versus time curves for each metal ion in the composition, wherein the superposition can be used to train an artificial neural network to determine the presence of beryllium ions and / or the concentration of beryllium ions in a medium.

[0020] Advantageously, the macrocyclic compound has unique kinetics in absorbing beryllium ions, so that when the macrocyclic compound is exposed to a medium having a certain concentration of beryllium ions, the resonant structure provides a unique curve of resonant wavelength relative to time, wherein the unique curve can be used to identify the beryllium ions and / or measure the concentration of beryllium ions in the medium.

[0021] Another aspect of the present invention provides a method for covering the surface of a resonant structure of an optical sensor with a layer of a macrocyclic compound so that the sensor can detect beryllium ions and / or measure the concentration of beryllium ions in a fluid medium, the method comprising the steps of: plasma treatment on the surface using oxygen; and treating the surface at room temperature using a 2% (v / v) 3-aminopropyltriethoxysilane (APTES) solution diluted in pure ethanol for a first predetermined time interval, characterized in that the surface is treated with 50 ml of a 100 mM diamino-benzo-9-crown-3 (DAB9C3) solution diluted in a solvent; and leaving the surface undisturbed so that the solvent in the DAB9C3 solution evaporates, so that a layer of the macrocyclic compound is formed on the surface.

[0022] Typically, the macrocyclic compound is diamino-benzo-9-crown-3.

[0023] Diamino-benzo-9-crown-3 is an ion carrier capable of chemically binding beryllium ions in a medium, so that the material index of diamino-benzo-9-crown-3 changes depending on the amount of beryllium ions thus bound.

[0024] In one embodiment, the method further comprises the steps of: drying the surface at 80°C for the first predetermined time interval; and treating the surface with a 0.1% (v / v) glutaraldehyde (GA) solution diluted in deionized water at room temperature for a second predetermined time interval.

[0025] Typically, the first predetermined time interval is 1 hour and the second predetermined time interval is 20 minutes.

[0026] Typically, the solvent is methanol.

[0027] Typically, the optical sensor comprises a Mach-Zehnder interferometer.

[0028] Yet another aspect of the present invention provides an optical sensor manufactured by the above method.

[0029] Advantageously, the resonant wavelength of the resonant structure shifts according to a change in the refractive index of the material.

[0030] Typically, when the macrocyclic compound is exposed to a medium having a composition of different metal ions, the resonant wavelength of the resonant structure shifts over time, and the shift in the resonant wavelength is a superposition of the resonant wavelength curves of each metal ion in the composition relative to time, wherein the superposition can be used to train an artificial neural network to determine the presence of beryllium ions and / or the concentration of beryllium ions in the medium.

[0031] Advantageously, the macrocyclic compound has unique kinetics in absorbing beryllium ions, so that when the macrocyclic compound is exposed to a medium having a certain concentration of beryllium ions, the resonant structure provides a unique curve of resonant wavelength relative to time, wherein the unique curve can be used to identify the beryllium ions and / or measure the concentration of beryllium ions in the medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

[0033] Figure 1 shows the mechanism according to the invention by which beryllium cations are trapped by a macrocyclic compound layer coated on the surface of a resonant structure;

[0034] Figure 2 shows that when the macrocyclic compound is exposed to a medium having a composition of different metal ions, the resonant wavelength of the resonant structure shifts over time;

[0035] Figure 3 shows a wavelength of light waves that is higher than the wavelength of light waves required to cause the resonant structure to resonate when the resonant structure is not coated with the macrocyclic compound layer;

[0036] Figure 4 is a plan view of a dielectric planar lightwave circuit (PLC) having waveguide segments of different widths;

[0037] Figure 5 is a top view of the sensor chip with its input connected to a laser source and its output connected to a spectral interrogator;

[0038] Figure 6 is a top view of a Mach-Zehnder interferometer system built on a silicon-on-insulator platform; and

[0039] Figure 7 is a graph of transmittance versus resonant wavelength, showing that as Be in the medium 2+ As the concentration increases, the resonant wavelength shifts. DETAILED DESCRIPTION

[0040] Certain macrocyclic compounds are used as Be cations (“Be 2+ ”) and can therefore be used to separate or remove Be from contaminated media. 2+ . Combined with Be 2+ The ability is attributed to the cavity of the macrocycle and the Be 2+ The ionic radii of Be 2+ Factors that determine the stability and selectivity of the macrocyclic compound include the cavity size, shape, substituent effects, conformational flexibility, type of donor atom, and solvent. 2+ The macrocyclic compound provides Be 2+ A close-fitting cavity and a set of Be 2+ The surrounding oxygen atoms are therefore useful for selectively separating Be from media such as complex water and nuclear waste. 2+ Promising results were achieved.

[0041] refer to Figure 1 , a form of optical sensor, which may be a Mach-Zehnder interferometer, comprises a resonant structure 1, such as a waveguide, the surface of which is coated with a layer 2 of a macrocyclic compound, namely diamino-benzo-9-crown-3 ("DAB9C3"). DAB9C3 is a macrocyclic compound that can react with Be in a fluid medium (such as a liquid or a gas). 2+ Chemically combine and form a 2+ The ion carrier of the complex 3 is composed of.

[0042] The method for coating the surface of the resonant structure 1 with a layer 2 of a macrocyclic compound comprises the following steps. First, in order to hydroxylate the surface, the surface is plasma treated with oxygen. Then, the surface is treated with a 2% (v / v) solution of 3-aminopropyltriethoxysilane ("APTES") diluted in pure ethanol at room temperature for 1 hour. Subsequently, the surface is completely dried at 80°C for 1 hour, after which the surface is treated with a 0.1% (v / v) glutaraldehyde ("GA") solution diluted in deionized water at room temperature for 20 minutes. The surface is then treated with 50 ml of a 100 mM diamino-benzo-9-crown-3 ("DAB9C3") solution diluted in a solvent (i.e., methanol). Finally, the surface is undisturbed so that the solvent in DAB9C3 evaporates, so that a layer 2 of the macrocyclic compound (i.e., DAB9C3) is formed or fixed on the surface.

[0043] The coated resonant structure 1 was functionalized with DAB9C3, which acts as a Be 2+ ligand, and thus can detect divalent cations of Be. 2+ When the medium is DAB9C3, the material index is based on the Be 2+ varies with the amount.

[0044] When the concentration of DAB9C3 immobilized on the surface was increased, Be 2+ In this way, the concentration of DAB9C3 can be adjusted according to the test requirements to optimize the detection range.

[0045] Since the layer of DAB9C3 is heterogeneously integrated with the resonant structure 1, the change in the material index changes the resonant condition of the surface of the resonant structure. Figure 2 As shown, when the macrocyclic compound is exposed to a medium having a composition of different metal ions, the resonant wavelength of the resonant structure shifts over time, and the shift of the resonant wavelength is a superposition of the curves of the resonant wavelength of each metal ion in the composition relative to time. This superposition can be used to train an artificial neural network to determine the presence of beryllium ions and / or the concentration of beryllium ions in the medium. The macrocyclic compound has unique kinetics in absorbing beryllium ions, so when the macrocyclic compound is exposed to a medium having a certain concentration of beryllium ions, it causes the resonant structure to provide a unique curve of resonant wavelength relative to time. The unique curve can be used to identify beryllium ions in the medium and / or measure the concentration of beryllium ions in the medium.

[0046] The higher the concentration of beryllium ions, the faster the resonant structure achieves the maximum resonant wavelength corresponding to the concentration.

[0047] The material index is a set of material properties that affect the properties of the layer. The properties include relative permittivity, thermal resistivity (°C.cm / W) and loss tangent. For silicon photonic sensors, the material index is usually the refractive index.

[0048] Resonance can be defined as a large amplitude vibration in a mechanical, electrical or optical system caused by a relatively small periodic excitation of the same or nearly the same period as the natural vibration of the system.

[0049] For optical sensors, resonance occurs at their resonant structure, and the periodic excitation is a light wave of a specific wavelength. This specific wavelength is called the resonant wavelength, that is, the wavelength of the light wave that causes the resonant structure to resonate.

[0050] Adding a macrocyclic compound layer to the surface of the resonant structure changes the conditions under which the resonant structure resonates. Figure 3 As shown, a higher wavelength of light is required to make the resonant structure resonate than when the resonant structure is not coated with the macrocyclic compound layer. 2+ As the concentration of increases, the material index of the macrocyclic compound layer changes, and the resonant wavelength of the resonant structure increases accordingly.

[0051] The resonant structure is an essential part of an optical sensor, where the macrocyclic compound is able to affect the wavelength of light passing through the structure. When light passes through the structure, the electric field propagates beyond the walls of the structure in the form of an evanescent field. This evanescent field is susceptible to the surrounding environment and therefore to the macrocyclic compound layer located on the outer surface of the structure. When the material index of the macrocyclic compound is due to Be 2+ When the absorption of a structure changes, the evanescent field is affected by the change and the resonant wavelength of the light passing through the structure increases accordingly.

[0052] refer to Figure 4 , the optical sensor can be a dielectric planar lightwave circuit ("PLC") having waveguide segments of different widths, typically arranged in pairs. Each end of the PLC has a fiber array assembly to which a fiber adapter is connected. The fiber adapter adapts the fiber to the PLC and vice versa. The circuit can be mass-produced by semiconductor wafer processing. At least one of the waveguide segments is coated with a layer of a macrocyclic compound. The coated waveguide segment acts as a resonant structure for the PLC.

[0053] refer to Figure 5 , multiple PLCs can be deployed in one or more mm 2 For each PLC, one of the waveguide sections is exposed 5, while the other is sealed 6 to prevent any contact with the medium (or not coated with the macrocyclic compound). During the test, the exposed section 5 provides a Be 2+The concentration wavelength, while the sealed section 6 provides the corresponding Be 2+ The input of the PLC is connected to a plurality of laser sources 7, and the output of the PLC is connected to a spectral interrogator 8, which acts as a Be 2+ Detector.

[0054] refer to Figure 6 , the resonant structure can also be deployed in a Mach-Zehnder interferometer ("MZI") system, which is built on a silicon-on-insulator ("SOI") platform. The input of the MZI system is a III-V waveguide 9, which is connected to a silicon slab interposer and a spot size converter ("SSC") 10. The interposer has a silicon dioxide SiO2 cladding and has a width of 6μm and a thickness of 0.07μm. The output of the interposer and SSC is coupled to a 1×2 multimode interferometer ("MMI") 11, whose output is diverged to an unbalanced MZI 12 and a waveguide sensing section 13, the latter of which is a resonant structure having a surface coated with a DAB9C3 layer. The waveguide sensing section 13 has a silicon dioxide SiO2 cladding and has a width of 15-1000nm, a thickness of 220nm, and a length of 200μm to 1cm. The other end of the unbalanced MZI 12 and the waveguide sensing section 13 converge to a 2×1 MMI 14, which couples them to an interrogator 15 fully integrated in the system. The MMIs 11, 14 deployed at both ends are vertical grating couplers, in which the transverse mode (“TM”) is preferred. The interrogator 15 includes a pair of MMI-based reflectors 16, 17 and 2 pairs of microring resonators (“MRR”) 18, 19, 20, 21. The MZI system provides a readout parameter of phase or λ (i.e., wavelength), a wavelength range of 1500 to 1600 nm, and a minimum resolution of 1 pm.

[0055] When testing with an MZI system, the following sequence can be observed. First, a distilled water droplet is added to the surface of the MZI system as a blank sample. Second, the distilled water droplet is removed from the surface. Third, a liquid with a known Be content is added to the surface. 2+ A drop of a solution of 1000 nm concentration was added. After 30 seconds to 2 minutes, the solution was removed from the surface. Then, a drop of distilled water was added to the surface again. Last but not least, the laser was scanned from a wavelength of 1500 to 1600 nm and the output of the sensor was measured.

[0056] Reference Figure 7 , the output of the sensor can be shown in a graph of transmittance versus resonant wavelength. 2+ As the concentration of Be increases, the resonance wavelength tends to shift to the right, i.e. become higher. This shift can be as high as 500 pm or more, and has been experimentally observed to be in the range of 340 to 430 pm, which can be used to identify Be2+ The presence of and measurement of its concentration in the medium.

[0057] The above method is relatively simple, but produces an optical sensor that is effective in detecting Be in aqueous or non-aqueous environments from 10 ppb to 200 ppm. 2+ The optical sensor is highly sensitive and selective in terms of its ability to detect Be. Multiple DAB9C3-coated resonant structures (e.g., mirror resonators) arranged in a photonic platform (e.g., Mach-Zehnder interferometer) have a much smaller footprint compared to ICP-MS or ICP-OES methods. Despite the smaller footprint, the optical sensor is able to detect Be 2+ And accurately measure its concentration.

[0058] In addition, the above method uses non-toxic solvents. The optical sensor fabricated by this method is compact and can be used for Be 2+ On-site, in-situ detection and measurement have great commercial value, especially in the fields of rare earth mining, aerospace, nuclear industry and ceramic industry.

[0059] Those skilled in the art will appreciate that the present invention may also include additional modifications that do not affect its overall functionality.

Claims

1. An optical sensor for detecting beryllium ions and / or measuring the concentration of beryllium ions in a fluid medium, comprising: a resonant structure (1), at least a portion of the surface of which is covered by a layer (2) of a macrocyclic compound, Characteristically, the macrocyclic compound is diamino-benzo-9-crown-3, and its material index varies depending on the amount of beryllium ions bound thereto.

2. The optical sensor according to claim 1, wherein: Diamino-benzo-9-crown-3 is an ion carrier that can chemically bind to beryllium ions in the medium, so that the resonant wavelength of the resonant structure (1) shifts over time according to the corresponding change in the material index, and this shift can be detected and / or measured.

3. The optical sensor according to claim 2, wherein: The resonant structure comprises a test waveguide (5) and a reference waveguide (6), the test waveguide (5) being exposed to the medium and the reference waveguide (6) being sealed to avoid any contact with the medium.

4. The optical sensor according to claim 3, wherein: A light source (7) is configured to emit light of at least one wavelength, the light being guided through the test and reference waveguides (5, 6), and a shift in the resonant wavelength is determined by comparing the patterns generated from the respective test and reference waveguides (5, 6), the shift corresponding to the concentration of beryllium ions in the medium.

5. An optical sensor as claimed in claim 4, further comprising a spectral interrogator (8) connected to the outputs of the test and reference waveguides (5, 6) capable of providing a reading of the wavelength or phase of the light.

6. The optical sensor according to claim 5, wherein: The test waveguide and the reference waveguide (5, 6) each have a width of 15-1000 nm and a length of 200 μm to 1 cm.

7. The optical sensor according to claim 6, wherein: The light source (7) comprises at least one laser source and is capable of emitting light with a wavelength ranging from 1500 nm to 1600 nm.

8. The optical sensor according to claim 5, wherein: During the test, the test waveguide (5) is exposed to the medium for a time interval of 30 seconds to 2 minutes.

9. The optical sensor of claim 8, further comprising a pair of multimode interferometers (11, 14), wherein one multimode interferometer is connected to an input end of the resonant structure (1) for diverging light, and the other multimode interferometer is connected to an output end of the resonant structure (1) for converging light.

10. The optical sensor of claim 9, further comprising: A silicon interposer and spot size converter (10) connected to the multimode interferometer (11) at the input end; as well as A waveguide (9) having an input connected to the light source and an output connected to the silicon slab interposer.

11. The optical sensor according to claim 10, wherein: The spectral interrogator comprises: a pair of reflectors (16, 17) based on a multi-mode interferometer and two pairs of micro-ring resonators (18, 19, 20, 21).

12. A method for covering the surface of a resonant structure (1) of an optical sensor with a layer (2) of a macrocyclic compound so that the sensor can detect beryllium ions and / or measure the concentration of beryllium ions in a fluid medium, the method comprising the following steps: performing a plasma treatment on the surface with oxygen; and treating the surface with a 2% (v / v) 3-aminopropyltriethoxysilane (APTES) solution diluted in absolute ethanol at room temperature for a first predetermined time interval; Characterized in that the surface is treated with 50 ml of 100 mM diamino-benzo-9-crown-3 (DAB9C3) diluted in a solvent; and The surface is left undisturbed to allow the solvent in the DAB9C3 solution to evaporate, resulting in the formation of a layer of the macrocycle on the surface (2).

13. The method of claim 12, wherein: The macrocyclic compound is diamino-benzo-9-crown-3, and its material index varies depending on the amount of beryllium ions bound thereto.

14. The method of claim 13, further comprising the steps of: drying the surface at 80° C. for the first predetermined time interval; and The surface is treated with a 0.1% (v / v) glutaraldehyde (GA) solution diluted in deionized water at room temperature for a second predetermined time interval.

15. The method of claim 14, wherein: The first predetermined time interval is 1 hour, and the second predetermined time interval is 20 minutes.

16. The method of claim 14, wherein: The solvent is methanol.

17. The method of claim 14, wherein: The optical sensor includes a Mach-Zehnder interferometer.

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