Underwater analyte sensing using a phononic crystal waveguide-based interferometric acoustic spectrometer

Abstract

Embodiments can relate to an acoustic spectrometer including a phononic interferometer. The phononic interferometer can include a phononic structure having reference arm defined by a defect-based waveguide and a sensing arm defined by a defect-based waveguide. The sensing arm defect-based waveguide can include plural cavities configured to disrupt symmetry of periodicity in the phonic structure. At least one cavity of the plural cavities can be an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm. When analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide can be shifted. The acoustic spectrometer can include a spectrum analyzer configured to detect a phase shift between the phonons propagating through the reference and sensing arms.

Description

UNDERWATER ANALYTE SENSING USING A PHONONIC CRYSTAL WAVEGUIDE-BASED INTERFEROMETRIC ACOUSTIC SPECTROMETERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is related to and claims the benefit of priority of U.S. provisional patent application no. 63 / 637,994, filed on April 24, 2024, the entire contents of which is incorporated herein by reference.FIELD OF THE INVENTION

[0002] Embodiments can relate to cavity -based acoustic spectrometers for detecting and measuring analytes in underwater environments.BACKGROUND OF THE INVENTION

[0003] Phononic crystals for sensing applications (e.g., interferometers) exist. However, existing systems require the entire sensing arm to be filed with analyte, thereby requiring large volumes of analyte. Such volumes pose practical limitations in certain applications due to difficultly controlling uniformity of the analyte.SUMMARY OF THE INVENTION

[0004] An exemplary embodiment can relate to an analyzer. The analyzer can include a phononic structure having a defect-based waveguide. The defect-based waveguide can include plural cavities configured to disrupt symmetry of periodicity in the phonic structure. At least one cavity of the plural cavities can be an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the defect-based waveguide.

[0005] In some embodiments, the phononic structure can be a sonic crystal, a phononic crystal, or an acoustic metamaterial.

[0006] In some embodiments, the phononic structure can be a 2D phononic crystal.

[0007] In some embodiments, when analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide can be shifted.

[0008] An exemplary embodiment can relate to a phononic interferometer. The phononic interferometer can include a phononic structure having a reference arm defined by a defect-based waveguide and a sensing arm defined by a defect-based waveguide. The sensing arm defectbased waveguide can include plural cavities configured to disrupt symmetry of periodicity in thephonic structure. At least one cavity of the plural cavities can be an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm.

[0009] In some embodiments, the phononic structure can be a sonic crystal, a phononic crystal, or an acoustic metamaterial.

[0010] In some embodiments, the phononic structure can be a 2D phononic crystal. In some embodiments, when analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide can be shifted.

[0011] In some embodiments, the phononic interferometer can include a detector configured to detect a phase shift between phonons propagating through the reference arm and phonons propagating through the sensing arm.

[0012] An exemplary embodiment can relate to an acoustic spectrometer. The acoustic spectrometer can include a phononic interferometer. The phononic interferometer can include a phononic structure having a reference arm defined by a defect-based waveguide and a sensing arm defined by a defect-based waveguide. The sensing arm defect-based waveguide can include plural cavities configured to disrupt symmetry of periodicity in the phonic structure. At least one cavity of the plural cavities can be an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm. The acoustic spectrometer can include a phonon generator including a phononic splitter. The phonon generator can be configured to generate first phonons to be propagated through the reference arm and second phonons to be propagated through the sensing arm, wherein the phononic interferometer is configured to allow the first phonons to propagate through the reference arm, the second phonons to propagate through the sensing arm, and to combine the first phonons with the second phonons after propagating through the reference arm and the sensing arm, respectively, to generate combined phonons. The acoustic spectrometer can include a phonon transducer configured to measure phonon energy associated with the combined phonons. The acoustic spectrometer can include a spectrum analyzer coupled to the phonon transducer. The spectrum analyzer can be configured to detect a phase shift between the first phonons and the second phonons of the combined phonons.

[0013] In some embodiments, the phononic structure can be a sonic crystal, a phononic crystal, or an acoustic metamaterial.

[0014] In some embodiments, the phononic structure can be a 2D phononic crystal.

[0015] In some embodiments, when the analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide can be shifted.

[0016] In some embodiments, the analyte cavity holder of the analyzer can be configured to confine blood analyte.

[0017] In some embodiments, the analyte cavity holder of the phononic interferometer can be configured to confine blood analyte.

[0018] In some embodiments, the acoustic spectrometer is Erythrocyte Sedimentation Rate (ESR) spectrometer. The analyte cavity holder can be configured to confine blood analyte. The spectrum analyzer can be calibrated to correlate instantaneous spectral shifts to sedimentation.

[0019] Further features, aspects, objects, advantages, and possible applications of the present invention will become apparent from a study of the exemplary embodiments and examples described below, in combination with the Figures, and the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, aspects, features, advantages and possible applications of the present innovation will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings. Like reference numbers used in the drawings may identify like components.

[0021] FIG. 1 shows exemplary embodiments of an analyzer, interferometer, and spectrometer using an embodiment of the phononic structure.

[0022] FIG. 2 shows exemplary acoustic spectrometer models created for sensing applications. Panel (a) shows an exemplary symmetric acoustic spectrometer indicating the number of induced defects, panel (b) shows an exemplary acoustic spectrometer with disruption in the 6thdefect site with neither a steel cylinder nor a glass tube tube in the left model can be included, panel (c) shows an acoustic pressure map from COMSOL simulation for the symmetric acoustic spectrometer at 432 kHz, and panel (d) shows a pressure map for the disrupted spectrometer when the 6thdefect was not induced.

[0023] FIG. 3 shows transmission features of the perfect AS and related arrays under analysis were simulated in COMSOL, experimentally recorded, and theoretically calculated. Panel (a) shows an exemplary band structure in the TX directions was calculated using the LinearizedNavier-Stokes through COMSOL Multiphysics with the supercell approach for the five different configurations (perfect PnC, AS, SS, GA-A, and GT-W). Panel (b) shows COMSOL transmission spectra of the interferometric models showing spectral shifting. Panel (c) shows experimental ttransmission response compared with the Tight-binding calculations for the GT-A and GT-W models.

[0024] FIG. 4 shows experimental analyses for the aqueous sucrose solutions sensing applications. Panel (a) shows an actual picture of the used AS spectrometer for sensing applications, with disruption in the 6thdefect site with neither the steel cylinder nor the glass tube in the upper pictures and the experimental setup in the lower sketch. Panel (b) shows an experimental acoustic transmission for the different sucrose concentrations where the blue shifting can be appreciated.

[0025] FIG. 5 shows tight-binding calculations for experimentally detrermined different sucrose concentrations. Panel (a) shows 0 % of sucrose concentrations, which means pure water, panel (b) shows 10 % of sucrose wt. concentration, and panel (c) shows 20 % of sucrose wt. concentration, and (d) 50 % of sucrose wt. concentration.

[0026] FIG. 6 shows that numerical simulation using COMSOL Multiphysics successfully reproduces these results. Panel (a) shows transmission spectra for different sucrose concentrations. Panel (b) shows an effect of changes in the sound velocity and density of the sucrose solutions, highlighting the greater impact of sound velocity on the observed blue-shifting phenomenon.

[0027] FIG. 7 illustrates a typical Modified Westergren test set up, wherein panel a) shows a typical Westergren tube and panel b) shows a typical set up of a Westergren tube on a rack.

[0028] FIGS. 8 A illustrates an exemplary cavity configuration within a defect waveguide based interferometric phononic crystal that can be used for an embodiment of an ESR acoustic spectrometer. FIG. 8B shows the defect based waveguide with microliter volume of blood.

[0029] FIG. 9 shows an exemplary simulation of acoustic waves propagating through the device of FIG. 8.

[0030] FIG. 10 shows an actual prototype of the device of FIG. 8.

[0031] FIG. 11 (panel a) is an actual picture of nanofluids after its preparation within a glass container, for both A (25 nm) and B (60-80 nm) samples. FIG. 11 (panel b) corresponds to the same two samples but after 60 minutes of preparation. FIG. 11 (panel c) is an actual picture ofthe nanofluids in the pipettes approximately 2 min after the samples were taken. FIG. 11 (panel d) is an actual picture of the nanofluids in the pipettes approximately 60 min after the samples were taken. FIG. 11 (panel e) is an enlarged view of the pipettes after two minutes, and FIG. 11 (panel f) is the same for the samples after 60 min.

[0032] FIGS. 12A and 12B show instantaneous spectral shift that had occurred due to sedimentation.

[0033] FIG. 13 shows a schematic of an exemplary automated ESR acoustic spectrometer system that can be used for ESR testing.DETAILED DESCRIPTION OF THE INVENTION

[0034] The following description is of exemplary embodiments that are presently contemplated for carrying out the present invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles and features of the present invention. The scope of the present invention is not limited by this description.

[0035] Referring to FIG. 1, any of the components (e.g., analyzer 100, phononic interferometer 102, acoustic spectrometer 104, detector 106, phonon generator 108, etc.) disclosed herein can include one or more processors 110 and one or more memories 112. The processor(s) 110 can be configured to execute instructions to facilitate signal processing, data manipulation, data storage, execution of algorithms, etc. For instance, any of the processors 110 can be in operative association with memory 112 which includes instructions (e.g., logic, algorithms, models, etc.) stored thereon that when executed by the processor 110 will cause the processor 110 to carry out one or more of the functions disclosed herein. It is contemplated for the processors to receive electrical, optical, electro-optical, and / or phononic signals, process those signals, perform computations with the processed signals, and transmits information and / or commands to other components. Thus, the processors 110 can be equipped with lead lines, waveguides, electrical / optical connectors / couplers, switches / circuity, processing blocks, analog-to-digital converters (ADC), digital-to-analog converters (DAC), filters, processing blocks, transceivers, antennas, and so forth to facilitate receiving / transmitting, processing, and storing signals and data.

[0036] Any of the processors 110 can include or be operatively associated with a memory 112. The memory 112 can store instructions thereon which can be executed by the processor 110 toperform any of the functions disclosed herein. The instructions can be in the form of computer logic, algorithms, models, etc. and stored as a computer program, a data structure, and so forth. While exemplary embodiments may be described and / or illustrated with one processor 110 and one memory 112, it is understood that any of the components can include any number of processors 110 and memories 112 within the single processor 110 or memory 112.

[0037] The processor 110 can be part of or in communication with a machine (logic, one or more components, circuits (e.g., modules), or mechanisms). The processor 110 can be hardware (e.g., processor, integrated circuit, central processing unit, microprocessor, core processor, computer device, etc.), firmware, software, or any combination thereof configured to perform operations by execution of instructions embodied in algorithms, data processing program logic, artificial intelligence programming, automated reasoning programming, etc. Use of processors 110 herein can include any one or combination of a Graphics Processing Unit (GPU), a Field Programmable Gate Array (FPGA), a Central Processing Unit (CPU), and so forth. The processor 114 can include one or more operating modules. An operating module can be a software or firmware operating module configured to implement any of the method steps disclosed herein. The operating module can be embodied as software and stored in memory 112, the memory 112 being operatively associated with the processor 110. An operating module can be embodied as a web application, a desktop application, a console application, and so forth.

[0038] The processor 110 can include or be associated with a computer or machine-readable medium. The computer or machine-readable medium can include memory. The computer or machine-readable medium can be configured to store one or more instructions thereon. The instructions can be in the form of algorithms, program logic, a model, or any combination therefor that cause the processor 110 to perform any of the functions described herein.

[0039] Any of the memory 112 discussed herein can be computer readable memory configured to store data. The memory 112 can include a volatile or non-volatile, transitory or non-transitory memory, and be embodied as an in-memory, an active memory, a cloud memory, or any combination thereof. Embodiments of the memory 112 can include an operating module and other circuitry to allow for the transfer of data to and from the memory 112, which can include to and from other components of a communication system. This transfer can be via hardwire or wireless transmission. The communication system can include transceivers, which can be used in combination with switches, receivers, transmitters, routers, gateways, waveguides, etc. tofacilitate communications via a communication approach or protocol for controlled and coordinated signal transmission and processing to any other component or combination of components of the communication system. The transmission can be via a communication link. The communication link can be electronic-based, optical-based, opto-electronic-based, quantumbased, phononic-based, etc.

[0040] The processor 110 can be in communication with other processors of other devices (e.g., a computer device, a desktop computer, a laptop computer, a computer system, etc.). Any of those other devices can include any of the exemplary processors 110 disclosed herein. Any of the processors 110 can have transceivers or other communication devices / circuitry to facilitate transmission and reception of wireless signals. Any of the processors 110 can include an Application Programming Interface (API) as a software intermediary that allows two applications to talk to each other. Use of an API can allow software of the processor 110 of the system to communicate with software of the processor of the other device(s), if the processor 110 of the system is not the same processor 110 of the device.

[0041] Any data transmission between a processor 110 and a memory 112, between a processor 110 and a database, between a processor 110 and processors 110 of other devices, between a processor 110 of one operating module and a processor 110 of another operating module, etc. can be via a pull operation (e.g., the processor 110 can pull the data) or a push operation (e.g., the data can be pushed to the processor 110). The processor 110 can receive and process the data in steaming format, store it in memory before being processed, etc.

[0042] The processor 110 can be configured to be a component of, used in combination with, or in communication with another device / system - e.g., this can include the processor being part of the device / system, the device / system being part of the processor, the processor in communication with the device / system, etc. “Being part of’ can include being on a same substrate or integrated circuit.

[0043] A processor 110 can be a component of, used in combination with, or in communication with a predictive modeling system, a decision support system, an automated control system, etc. A processor 110 can use the techniques disclosed herein to assist with or augment the performance of these devices / sy stems.

[0044] Embodiments can relate to an analyzer 100. The analyzer 100 can be configured to detect presence of a substance and / or measure characteristics of the substance (e.g.,concentration, chemical composition, etc.), it is contemplated for the substance to be in solution form. The analyzer 100 can be configured to receive the solution and analyze it as an analyte, for example. The analyzer 100 can include a phononic structure 114. For instance, the analyzer 100 can include media engineered to control or manipulate phonons propagating through the media. For instance, the media can be a sonic crystal(s), a phononic crystal(s), and / or an acoustic metamaterial(s) exhibiting variation in periodic structure (e.g., material properties, geometries, etc.) so as to form one or more acoustic band gaps (e.g., booking or attenuating phonon frequencies) and one or more acoustic wave guide channels (e.g., permitting phonon frequencies). This can be achieved by engineering properties such as bulk modulus, mass density, chirality, etc. to allow portions of the phononic structure to interact with (e.g., transmit, trap, amplify, attenuate, etc.) phonons of certain phonon frequencies. The engineered properties can exhibit a periodicity, and the periodicity can be engineered to generate one or more propagation channels and one or more band gaps. The variation in periodicity can be in ID, 2D, and / or 3D. Exemplary phononic structures can be pillar arrays formed on a substrate, acrylic polymers, Helmholtz resonators, space-coiling structures, split-ring resonators, etc.

[0045] The phononic structure 114 can have one or more defect -based waveguides 116. A defect-based waveguide 116 can be a variation in the periodicity of the structure so as to generate a phononic channel. One or more of the defect-based waveguides 116 can include plural cavities 118. One or more of the cavities 118 can be configured to disrupt symmetry of periodicity in the phononic structure 114. At least one cavity 118 of the plural cavities 118 can be an analyte cavity holder. For instance, the analyte cavity holder can be configured to confine analyte fluid therein when analyte fluid is introduced into the defect-based waveguide 116. When analyte fluid is confined to the analyte cavity holder 118, phonon propagation characteristics of the defect -based waveguide 116 is shifted (e.g., the path, speed, frequency, amplification, attenuation, etc. of the phonon(s) propagating through the defect-based waveguide 116 changes).

[0046] It should be noted that only a volume of analytic fluid necessary to be confined within the analyte cavity holder 118 is required to provide a shift in phonon propagation characteristics for the entire waveguide 116. This is in contrast to conventional analyzers that require analyte to occupy the entire waveguide structure to induce a shift in phonon propagation characteristics.

[0047] Building on the basis of the analyzer 100, embodiments can relate to a phononic interferometer 102. The phononic interferometer 102 can include a phononic structure 114having a reference arm(s) 120 defined by a defect-based waveguide(s) 116 and a sensing arm(s) 122 defined by a defect-based waveguide(s) 116. One or more of the sensing arm defect-based waveguides 116 can include plural cavities 118 configured to disrupt symmetry of periodicity in the phononic structure 114 . At least one cavity 118 of the plural cavities 118 can be an analyte cavity holder 118 configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm 112. When analyte fluid is confined to the analyte cavity holder 118, phonon propagation characteristics of the defect-based waveguide is shifted. The phononic interferometer 102 can include a detector 106 (e.g., transducer, spectral analyzer, etc.) configured to detect a phase shift between phonons propagating through the reference arm 120 and phonons propagating through the sensing arm 112.

[0048] Building on the basis of the phononic interferometer 102, embodiments can relate an acoustic spectrometer 104. The acoustic spectrometer 104 can include one or more phononic interferometers 112. Any of the phononic interferometers 112 can be any of the phononic interferometers 112 disclosed herein. For instance, the phononic interferometer 102 can include a phononic structure 114 having a reference arm 120 defined by a defect-based waveguide 116 and a sensing arm 112 defined by a defect-based waveguide 116. The sensing arm defect-based waveguide 116 can include plural cavities 118 configured to disrupt symmetry of periodicity in the phononic structure 114 . At least one cavity 118 of the plural cavities 118 can be an analyte cavity holder 118 configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm 112.

[0049] The acoustic spectrometer 104 can include a phonon generator 108. The phonon generator 108 can be an electronic hardware and / or software device configured to generate phonons at desired frequencies and amplitudes (e.g., an acoustic frequency generator, a tone generator, microphone, audio transducer, etc.). The phonon generator 108 can include a phononic splitter 124 (e g., phonon beam splitter) configured to split a phonon beam into two phonon beams, which can be equal or matched in amplitude, frequency, phase, etc.). The phonon generator 108 can be configured to generate first phonons (e.g., a first phonon beam) to be propagated through the reference arm 120. The phonon generator 108 can be configured to generate second phonons (e.g., a second phonon beam) to be propagated through the sensing arm 112. The phononic interferometer 102 can be configured to allow the first phonons to propagate through the reference arm 120, the second phonons to propagate through the sensing arm 112,and to combine the first phonons with the second phonons after propagating through the reference arm 120 and the sensing arm 112 , respectively, to generate combined phonons. For instance, the phononic structure 114 can be coupled to the phonon generator 108 as the phononic splitter 124 so that the firs phonons are directed to the reference arm 120 and the second phonons are directed to the sensing arm 112. The phononic structure 114 can also include an analyte input port configured to receive analyte fluid and direct it to the sensing arm 112. The reference arm 120 can be a path having a length Lr and the sensing arm 112 can be a path having a length Ls. The reference arm 120 path, at some point, coincides with the sensing arm 112 path such that the first phonons combine with the second phonons to generate combined phonons. The combined phonons interact to constructively interfere, destructively interfere, or a combination of both.

[0050] The acoustic spectrometer 104 can include a phonon transducer 106. The phonon transducer can be configured to measure phonon energy associated with the combined phonons (e.g., convert pressure to electrical, optical, opto-electrical, etc. signals). These signals can be transmitted to a detector 106 (e.g., spectrum analyzer 106 coupled to the phonon transducer 106). The spectrum analyzer 106 can be configured to detect a phase shift between the first phonons and the second phonons of the combined phonons. For insurance, the spectrum analyzer 106 can include software or be calibrated to detect a deviation of phonon energy that is expected of the combined phonons. As an example, suppose the acoustic spectrometer 104 is intended to measure concentration of compound A in a solution. The solution can be introduced into the acoustic spectrometer 104 at the analyte input port to allow the solution to flow into the sensing arm 112. The phonon generator 108 can then propagate first and second phonons in the reference and sensing arms 120, 122. The propagation characteristics of the phonons travelling through the sensing arm 112 will be modulated based on the presence and / or concentration of compound A within the solution. In particular, when the solution is confined to the analyte cavity holder 118, the presence and / or concentration of compound B in the confined solution will alter phononic propagation characteristics in the sensing arm 112 defect-based waveguide 116. This will change the path, speed, frequency, etc. of the phonons propagating therethrough. When the first and second phonons are recombined, they will be in- or out-of-expected phase based on the presence or concentration of compound B. Suppose the interferometer is designed such that the reference and sensing arms (in the absence of any compound B) will 100%constructively interfere with each other. Then the spectrum analyzer 106 can be calibrated to determine that no compound B is present if it detects a signal from the phonon transducer 106 that is representative of a sum of first and second phonon energies. If it is less than the summation, then compound B is present. The spectrum analyzer 106 can be calibrated such that the degree of deviation from the summation is representative of the degree of concentration of compound B.

[0051] EXAMPLES

[0052] The following examples include exemplary implementations and test results of embodiments disclosed herein.

[0053] EXAMPLE 1

[0054] Examples relate to a 2D PnC-based acoustic spectrometer capable of analyzing small solution volumes (25 pl) in aqueous environments with significative accuracy and reliability, thus addressing key limitations in current acoustic spectroscopic techniques. By optimally introducing rows of defects into the PnC structure, we enable guided acoustic modes to propagate at desired frequencies within the bandgap. Leveraging the properties of acoustic cavities within these waveguides, capable of confining and modulating wave propagation, we construct an acoustic interferometer. Our approach involves harnessing the interference between acoustic waves in the two arms of a defects-based waveguide within a PnC, one arm containing an analyte cavity-holder. We demonstrate that the presence of an analyte (sucrose solutions at various concentrations) induces alterations in the acoustic properties of the cavity, leading to observable shifts in transmission characteristics of the propagating acoustic modes. Through experimentation, we achieve exceptional spectral resolution, facilitating highly sensitive acoustic sensing even with small analyte volumes (< 25 pl). To validate our findings, we utilize finite element method simulations to predict spectral shifts resulting from modified acoustic interference. Additionally, we provide a phenomenological description using tight-binding models. Notably, our approach surpasses conventional PnC sensors like Mach-Zehnder interferometers by overcoming challenges associated with analyte uniformity.

[0055] Phononic crystals (PnCs) have increasingly been utilized for the control of acoustic wave propagation, offering the ability to tailor transmission bandgaps and exhibit anomalous dispersion characteristics. The shapes and symmetries of scatterers and the equifrequency surface of the PnCs, characterized by specific periodicity and lattice parameters, serve as passivestructures for manipulating the propagation of acoustic waves. These PnCs-based structures have found applications in various fields, including acoustic lenses, acoustic demultiplexers, energy harvesting, non-reciprocal acoustic devices, and sensing applications. Additionally, PnCs have conventionally been employed as sensors by monitoring the shift in transmission frequency for a specific bandwidth within their bandgaps. On the one hand, PnCs-based sensors have predominantly been reported in the form of ID periodic structures, where the analyte is confined within a period of the grating-like structure. On the other hand, 2D hollowed plates featuring a resonant cavities or single and periodic defects can be utilized as a means to confine the analyte, resulting in a modification of the acoustic environment that can be exploited for sensing purposes. In these sensor configurations, which utilize either ID or 2D PnCs-based cavities, the design intentionally introduces a holder-containing cavity that disrupts the symmetry of the periodic arrangement. These cavities act as defects, with the sensitivity of the periodic PnC cavities to a specific confined acoustic mode primarily determined by the Q factor. The properties of the analyte, including its viscoelastic, physical, and chemical characteristics, influence the bandwidth and resonant frequency of the cavity.

[0056] For instance, sensors based on ID PnCs consisting of an array of glass and fluid layers have been used to investigate variations in binary mixtures of water and ethanol percentages by confining the fluid within a centered liquid layer with different widths. The design was modified to include temperature dependence, utilizing solely the central layer as the holder analyte. The theoretical exploration of biofuel sensing through such temperature dependent ID PnC sensors has also been explored. The use of the central layer as the sample chamber enables the sensing of diverse analytes and complexes, including glucose, dihydrogen peroxide, and acetone. Additionally, these sensors allow for the measurement of gasoline concentrations and various component percentages. Gas sensing, encompassing gases such as O2, CO2, NH3, and CH4, has also been investigated using one-dimensional PnCs.

[0057] Moreover, 2D PnCs have been more extensively studied for sensing applications. Hollowed metallic plates have been employed to create cavities capable of distinguishing between characteristics of the infilled fluid, such as the distinction between water and ethanol or Dl / propanol mixtures. A hollowed steel plate with apertures (1.8 mm diameter) within a 2D square lattice has been utilized to determine the properties of gasoline with ethanol, and the octane number of gasoline or liquid mixtures with a different molar ratio of DI water / 1 -propanol.Sensors based on 2D PnCs utilize local or linear defects to create multichannel waveguides with tailored resonant frequencies as sensor parameters. These waveguides incorporate cavities that enhance the density of states, serving as analyte holders for detecting molecular or chemical changes in confined fluids within the cavity. Such techniques have been employed to estimate the concentration of hydrogen peroxide (H2O2) in water, sodium iodide concentrations in water, and the temperature of methyl nonafluorobutyl ether within the range of 10-40°C. Additionally, multichannel detection in phononic crystal waveguides for detection of heavy metals pollutions in water has also been demonstrated.

[0058] Furthermore, PnCs have been integrated into acoustic Mach-Zehnder (MZ) interferometer like structures for sensing applications, with one arm functioning as an analyte holder. One example is a structure consisting of a steel background with water-filled holes as inclusions, featuring two unequal pathways to exploit the interferometric advantages of the asymmetric MZ interferometers. This configuration demonstrated frequency changes in resonant modes by varying the material concentration of water-ethanol mixtures filling the MZ array.Another approach involved MZ interferometer configurations using a square lattice composed of the circular water inclusions immersed in an aluminum background, creating a symmetric Y- shape MZ. Results revealed that changes in the properties and temperature of the water inclusions in the sensing arm led to different output phase shifts. Additionally, a PnC sensor utilizing self-collimated beams, constructed with a square array of steel cylinders in a MZ array, exhibited the capability to detect variations in the weight fraction of ethanol in water. It is worth noting that the aforementioned MZ interferometers utilize multiple cavities as holders for sensing the analyte, such as 46 rods of 2mm radius filled or the entire background in the sensing arm which implies a large volume requirement for the analyte. This volume requirement can pose practical limitations in certain applications because the use of a large-volume solution in these MZ interferometers presents challenges in terms of controlling the uniformity of the analyte. Thus, the requirement for a substantial volume of solution can make it difficult to maintain consistent properties throughout the entire sample. This lack of uniformity can introduce uncertainties and limitations in the accuracy and reliability of the sensing measurements.

[0059] To address these challenges, this study presents a novel approach for analyzing small solution volumes (< 25 / / / ) in an aqueous environment using a 2D PnC -based acoustic spectrometer. Embodiments of the disclosed acoustic spectrometer (AS) can operate bymeasuring the variations in the transmission characteristics of analytes within an acoustic cavity. The fabrication process involved leveraging the interference between acoustic waves propagating through the two arms of a defects-based waveguide embedded in a PnC structure. Specifically, an MZ-type interferometric configuration was employed, where the analyte was positioned within a cavity holder located in one arm of the waveguide. The acoustic properties of the cavity were modified by introducing an analyte into a microstructured glass tube. This alteration in the acoustic impedance of the analyte caused a deviation in the path of the acoustic wave traveling through the interferometer arm containing the cavity, resulting in a spectral shift in the interference pattern. This shift correlated with distinct physical and chemical properties of the analyte. To validate the effectiveness of the proposed MZ-type interferometric device, experimental verification was conducted using sucrose water solutions at varying concentrations. The obtained results aligned with numerical simulations employing the Finite Element Method (FEM) and were further phenomenologically described using the tight-binding (TB) model and scattering theory.

[0060] In summary, the examples demonstrate:Artificially engineered acoustic waveguides are used for guided acoustic modes at desired frequencies within the bandgap of a PnC to build a defect-based MZ-like- interferometer.The presence of an analyte alters the acoustic properties of the cavity, leading to a shift in the transmitted acoustic modes, traduced in an acoustic sensing for a low amount of analyte (25 pl).The volume necessity in conventional PnC-based sensor-like MZ-interferometers is a challenge; yet, embodiments disclosed herein provide for analyzing small solution volumes in aqueous environment using PnCs.

[0061] Experimental Methods

[0062] This work aimed to design and demonstrate an interferometric AS for analyte sensing tests using cavities within the defect-based waveguide of a PnC. The spectral properties were analyzed experimentally and verified through numerical simulations. A square lattice PnC was fabricated using 20x 19 stainless steel rods with a radius of 0.8 mm and a length of 100 mm, witha lattice parameter of 2 mm. Acoustic waveguides were created in the PnC through defects' channels induced by removing rods, as shown in FIG. 2 (panel a). An interferometric waveguide in the MZ configuration was fabricated within the PnC. Asymmetric arms were created by introducing an additional defect in one of the waveguides, which acted as a cavity for confining the acoustic modes as depicted in FIG. 2 (panel b). Two immersion transducers (Olympus V301) were used as emitter and receiver, positioned at the two ends of the PnC waveguide approximately 2 mm apart from the facets. The emitter was connected to a broadband signal frequency generator (Teledyne LeCroy, WaveStation 2012), and the receiver was coupled to a spectrum analyzer (Tektronix-MDO3024) to measure the ultrasonic spectrum for each phononic structure within the frequency range of 380-500 kHz.

[0063] Numerical Simulations

[0064] The band structure of superlattices and the transmission of the AS were numerically calculated using COMSOL Multiphysics software. The Linearized Navier-Stokes model coupled with Solid Mechanics physics was utilized to determine the frequency dependence of the transmission, averaged over an area of the output. The stainless-steel rods in water were treated as elastic, and no-slip boundary conditions were applied to the surface of the rods. To ensure accuracy, the maximum grid size was set to one-twentieth of the wavelength. Additionally, perfectly matched layers were introduced around the AS in the simulations to account for the absorption of reflections from outside the boundaries.

[0065] Results and Discussion

[0066] The PnC-based AS utilizes square arrays of stainless-steel cylinders (0.8 mm radii) arranged in a 2 mm lattice parameter within a water medium. The AS configuration included 20x 19 2D arrays as shown in FIG. 2 (panel a). This AS is a conventional MZ interferometric waveguide-like device in two dimensions with an input port located at the 1stdefect site on the PnC, as illustrated in FIG. 2 (panel a). The input signal at the waveguide is split into two pathways at the 2nddefect leading to propagation through the two symmetric arms to be recombined at the 14thdefect site. The resulting interfering signal is eventually extracted through the defect waveguide at the output port (15thdefect site). Due to the symmetry of the waveguiding interferometric arms, the waves propagating through the two channels of the interferometric waveguide exhibit identical characteristics for any frequency supported by the waveguide. The spectral characteristics of the perfect PnC have been previously reported andhave a functional phononic bandgap between 380-480 kHz. The defect waveguides modify the band gap and contribute to additional transmission minibands. The symmetry of the interferometric waveguide can be disrupted by altering the defect states in one of the waveguide arms with a cavity filled with analyte along the defect array row, as sketched in FIG. 2 (panel b). FIG. 2 (panel c) illustrates the acoustic pressure map at 432 kHz of the non-disrupted acoustic spectrometer (termed as a perfect AS), while FIG. 2 (panel d) is the map at the same frequency but when the 6thdefect site was not induced, e.g., keeping the steel rod at that position. Both acoustic pressure maps were obtained through the FEM, COMSOL-Multiphysics. These acoustic pressure distributions show that the waves travel along the designed acoustic waveguide and are perfectly symmetric for the AS without broken symmetry. However, the presence of the analyte in the 6thsite modifies the transmission features, decreasing the transmitted power, as can be interpreted from the color scale.

[0067] In the acoustic spectrometer, each defect functions as a resonator, allowing a resonant mode with its frequency within the bandgap interval. The collective behavior due to the coupling between the allowed modes results in the formation of new transmission bands within the bandgap. The band structure features for the AS were calculated using COMSOL. The multiphysics, the linearized Navier-Stokes coupled to the solid mechanics, and eigenfrequency solver were used with the superlattice approaches to calculating the bandstructure along TX direction in the Brillouin zone of the superlattice, i.e., 7><3 array, shown in the upper unit cells of FIG. 1 (panel a). The phononic crystal’s symmetric condition is considered as the perfect AS configuration (without any modification at the 6thdefect site). The calculations were performed for the perfect AS and intentionally induced asymmetric configurations.

[0068] The band structure of the perfect PnC supports a bandgap between 380-475 kHz approximately, as represented by the gray-shaded region in the first band structure of FIG. 3 (panel a). The symmetric spectrometer (AS) asymmetric MZ interferometer was simulated when the 6thdefect site was considered to be replaced by a solid steel cylinder (SS cavity), an air-filled hollow glass tube (GT-A cavity), and a water-filled hollow glass tube (GT-W cavity). All the calculations show that the presence of the defects array forming the AS yields eigenstates solutions for frequencies within the bandgap, allowing new transmission bands between 404-461 kHz, approximately. The band structures in FIG. 3 (panel a) depict that various non-degenerate eigenmodes are supported within this particular interval of the band structure represented for thesteel arrays, with and without the glass tube filled with the analytes (air or water). It should be noted that the supercell approximation has complete information on the phononic environment and the material properties for the glass, and is influenced by the material properties and geometry of the periodic structure. Thus, the change in the material properties of the component contained in the 6thsite has been used to induce a spectral shifting in the resonant modes and applied as a parameter for analyte sensing.

[0069] The designed acoustic spectrometers induced several resonant (absorption) peaks at different frequencies. As described in the Methods section, the AS spectrometer was built within a PnC and experimentally characterized through ultrasonic spectroscopy. FIG. 3 (panel b) shows the simulated spectra for the four different configurations that were designed. Several absorption dips in transmission were recorded for the SS cavity configuration (black line). These absorption peaks occurred due to destructive interference when both waves were mixed in the 14thdefect with the path difference in the presence of dephasing effects because of the avoided 6thdefect site, which contributed to the spectrum’s bandwidth. A specific absorption peak was recorded for the SS cavity at 437.4 kHz. The air-filled glass tube (GT-A cavity) resulted in an absorption peak centered at 436.00 kHz, which shifted to 435.80 kHz when it was water-filled (GT-W cavity), accompanied by a slight increase in absorption intensity, as seen in FIG. 3 (panel b). These results confirm that the absorption peak characteristics depend on the material inside the glass tube.

[0070] The emergence of the new transmission band in the AS and related configurations is a result of mode coupling. The tight-binding (TB) approximation was used to phenomenologically support the experimental results of the acoustic interferometer in various configurations and confirm to the numerical simulation. The TB analysis is based on the fact that the defect-based configuration forming the acoustic spectrometer, can be assumed as Coupled Resonator Acoustic Waveguides (CRAWs). According to the TB approximation, the unoccupied sites (defect sites) embedded in a two-dimensional local periodic structure or finite PnC correspond to defect cavities or impurities. Those defect cavities are designed so that their corresponding resonant frequencies lie within the bandgap of the finite PnC, allowing the localization of the resonant modes of the respective impurities. The schematics based on steel cylinders in water with and without defects have already been described in FIG. 2 (panels a and b). The weak coupling between neighboring resonators, via evanescent Bloch waves, yields the nearest-neighbor tight-binding approximation usually found in solid-state physics. This description is similar to the one to optical coupled-resonators, acoustical, and phononic waveguides. The following nearest- neighbor TB Hamiltonian can describe the model depicted in FIG. 2:

[0071] f^nis the resonance frequency of the defect (site) cavities at positions |n, m) and v^mis the hopping frequency to nearest neighbors. Furthermore, for the tight-binding model of FIG.1 (panel b), an additional defect at the position |6, 6) is considered, assigned with red color in FIG. 2 (panel b). This defect has, in general, a site frequency fcand hopping frequency to the nearest neighbors vcdifferent than those of the rest of the other defect cavities.

[0072] FIG. 2 (panels a and b) can be opened by attaching two semi-infinite single modes to them. These modes correspond to the perfect system with coupling strength FL,Rfrom the left (L) and right (R) sites, respectively, or at the 1stand 15thpositions. Since in the experiments, the coupling losses can lead to a certain drop in the transmitted intensity, the 2*2 scattering matrix in the presence of absorption, S-matrix, can be written as:

[0073] r(r') and t(t') are the reflection and transmission amplitudes when the incidence is from the left (right), 12is the unit matrix of dimension 2, k = arccos (f / 2) is the wavevector at frequency f supported in the leads, andis the effective non-Hermitian Hamiltonian given by:

[0074] H is the N x N Hamiltonian matrix that describes the model in the presence of absorption y with N resonant states, Htlv— Htlv— iyS^, where Sfi vis the usual Kronecker delta. In equations (2) and (3), the matrix W, where the super-script T indicates the matrix transposition operation, is an A x 2 matrix that couples the N resonant states of the closed sample to the two propagating modes in the channels. Its elements are defined by:with the coupling amplitudes given by:

[0075] Furthermore, the frequency dependence in Heff can be neglected since arccos (J / 2) changes slightly at the center of the band. Then, from the two-channel S(f) -matrix of equation (2), the transmission is obtained from the transmission amplitude as |t|2= 11' |2.

[0076] Before applying the tight-binding model and the scattering approach described above, further simplifications of Hamiltonian (1) can be made. On the one hand, for the AS, all the defect cavities except the one at the position |6, 6), are roughly equivalent and have the same resonance frequency, i.e.,= fswith hopping frequency v = Vjt= Vs. On the other hand, for the defect at the position |6, 6), f6= fcwith hopping frequency given by v6= vc. Since fsand vsdetermine the center and width of the band (the bandwidth is four times vs)

[0053] , those parameters can be obtained directly from the experimental data. Furthermore, in experimental setup, various sources of power losses can occur, such as losses at the solid liquid interface or due to the viscosity of the liquid used. However, when modeling these systems using TB model, these losses are conveniently incorporated as an effective absorption parameter denoted by y. Interestingly, an estimation of absorption can be derived from the experimental data, as y is half the peak resonance width associated with the defect cavity.

[0077] In FIG. 3 (panel c), the experimental transmitted power for the AS with the described crystal tube filled with air (red), and water (blue), as defect cavities, compared with the tight- binding model (black continuous lines), is shown. As stated above, for the TB model, the defectcavities have, in general, a site frequency fcand hopping frequency to the nearest neighbors vcdifferent than those of the rest of the other site cavities. Those parameters, such as site and hopping frequencies for the site and defect cavities, are determined by adjusting the calculations to the experimental data.

[0078] The TB model has been estimated for the defect cavity with the glass tube filled with water. The site cavity related to the water-filled (GT-W cavity) glass tube (assigned by s) results in the resonant and hopping frequencies fs= 436.25 kHz and Vs= 12.62 kHz, respectively. The resonant frequency of the water-filled glass tube is fc= 436.25 kHz with a hopping frequency to nearest-neighbors of vc= 0.05 kHz. In this case, the absorption parameter is y = 0.30 kHz. On the other hand, for the TB model with an air-filled glass tube (GT-A cavity), the resonant and hopping frequencies of the site cavities are fs— 436.40 kHz and vs= 12.50 kHz, respectively, while the resonant frequency of the air-filled glass tube is fc= 436.40 kHz with a hopping frequency to the nearest-neighbors of vc= 0.05 kHz, with an absorption parameter y = 0.65 kHz. Notice that the glass tube or defect cavities slightly change the site frequency of the AS and are almost decoupled to its nearest-neighbor-site cavities. Furthermore, water or air in the glass tube produces further losses of the transmitted intensity. Even though some deviations between the TB model (black continuous lines) and the experimental spectra (red and blue continuous lines) are observed at the edge of the spectrum, the TB model qualitatively conforms to the experimental data. The central frequency, including the transmission spectrum splitting, is in complete agreement with the experiment. The coupling strength at the left and right cavities, e.g., at the 1stand 15thimpurity, respectively, is 15.0 kHz. A summary of the discussed TB parameters for this analysis is shown in the first two rows of Table I:TABLE IPARAMETERS FOR CONSTRUCTING HAMILTONIAN (1) AND S-MATRIX (2) ALONG WITH EQUATIONS (3)-(5) FOR THE CORRESPONDING ANALYTE STUDIED

[0079] The agreement of the resonant frequency shift due to the modification of the material characteristics of the fluid in the cavity from theoretical and experimental results was used as the basis for analyte sensing. Both FEM and TB analysis can be applied to predict those resonant modes. In the 6thdefect position, as described, a hollow glass tube was experimentally (Pasteur pipette) inserted in the place of the steel cylinder, as shown in FIG. 4 (panel a), which is an actual picture of the designed AS. The tube is used to hold the analyte being tested. The glass tube was sealed from the top and bottom and filled with red-colored water for better visualization. The analyte of interest was injected into the glass tube using a micropipette. Sucrose solutions of various concentrations were prepared by varying the weight in mass percentages. A 0% wt sucrose mass indicated a pure water sample. In comparison, the 10% wt sample contained 1 g of sucrose in 10 ml of solution (9 ml water), the 20% wt sample contained 2 g of sucrose in 8 ml of water, and the 50 % wt sample contained 5 g of sucrose in 5 ml of water. FIG. 4 (panel a) bottom illustrates the experimental setup.

[0080] The plot in FIG. 4 (panel b) shows the experimental transmission for each sample in the 432-440 kHz range. The green line representing the perfect AS can be considered as the reference where no absorption peak is recorded. The glass tube filled with water (0 % wt. sucrose mass) induced an absorption peak at 437.08 kHz, serving as the baseline. As seen in FIG. 4 (panel b), the absorption peak is influenced by an increase in sucrose content in the solution, mainly due to the intrinsic changes in its acoustic properties, such as density and sound velocity. In the case of the 10 % wt sucrose mass solution, the absorption peak shifted to 436.92 kHz, indicating a A / = —0.16 kHz spectral shift (A / ) relative to the reference (pure water). For the 20 %, the peak at 436.84 kHz with a A = —0.24 kHz shift compared to pure water. The absorption peak consists of two well-defined peaks for the highest sucrose weight with a mass of 50 %. The first peak corresponds to the previously observed peaks, similar to the previous two samples (436.80 kHz with a A) = —0.28 kHz). The second peak was observed at 436.40 kHz( f = —0.68 kHz). An increase in the sucrose content induces a blue shift of the absorption peak by approximately -0.68 kHz for the highest weight mass.

[0081] A similar blue shift behavior was theoretically predicted for Nal-water mixtures using 2D stainless steel hollowed plates. The blue shift in our case is lower than that reported in previous work (1.7 kHz), which is attributed to the small interaction volume of the analyte in the cavity. The glass tube in our AS-based sensor device was a Pasteur pipette (ESBE Scientific) with approximately 0.80 mm outer radii, as the steel cylinders, and 0.50 mm inner radii, with 0.30 mm thin wall. The micropipette contains a small volume of the analyte 0.078 cm3(78 « / ) as the pipette height is 10 cm. Despite the small volume of the analyte, a significant shift was still observed, indicating the high sensitivity of the acoustic spectrometer for measuring the small volume of the analyte. Moreover, considering the emitter is 2.54 cm, the real analyte necessary volume could be 19.94 / / / .

[0082] Based on the experimental results, the FWHM was observed to be 2 kHz for 0% and 10% wt sucrose mass solutions. For 20% and 50% wt, the FWHM values were 2.36 and 2.5 kHz, respectively, slightly reducing the quality factor (Q). Additionally, as depicted in FIG. 4 (panel b), the absorption intensity decreases by approximately 3.5 dBm as the % wt sucrose mass increases from 0% wt to 50 %wt. Consequently, the increase in sugar concentration leads to an increment in FWHM and a decrease in the absorption strength. Furthermore, the absorption peaks exhibit a blue shift and split into two resonances for higher concentrations, with a separation of 0.4 kHz. Table II summarizes these useful parameters for sensing analysis. The absorption intensity was obtained by subtracting the power at the central frequency fQfrom their corresponding transmitted power for the AS (green line in FIG. 4 (panel b).TABLE IISENSING PARAMETERS AS RESULT OF THE SUGAR CONCENTRATION CHANGES IN THE ANALYTESSucrose FWH Absorp / o A / Concentr M tion(kHz) (kHz) ation (%) (kHz) (dBm)0 Z0 437.08 - 20.71710 2.0 436.92 -0.16 19.90720 2.36 436.84 -0.24 19.253436.80 -0.28 18.10150 2.40436.40 -0.68 17.945

[0083] The spiting phenomenon could be explained by considering that the sugar become compressed against the pipette walls as the acoustic wave propagates, similar to dust on a speaker. However, a more comprehensive experimental analysis is necessary to convincingly explain all these insights. These observations may arise from an increase in the viscosity of the sugar-based analytes, leading to losses or scattering effects. Scattering could be responsible for the decrease in the absorption intensity.

[0084] The above-described tight-binding theory was carried out to investigate the effect of the sucrose solutions' acoustic properties on the AS's spectral features. In all those cases, the hopping frequency of the defect cavities and the water-glass tube defect cavity are 9.5 and 0.11 kHz, respectively. At the same time, the absorption strength is y=0.15 kHz, and the coupling strength at the left and right impurities, 1stand 15thimpurity (see FIG. 2 (panel b), is 12.5 kHz. Note the AS is highly sensitive to the sucrose concentration of the water-filled glass tube defect cavity, which triggers a linear shift in the site frequency of the defect cavities. Furthermore, a good agreement between the TB and the experiment is observed, as described in FIG. 5 (panels, a, b, c, and d) for each sucrose concentration 0, 10, 20, and 50 %, respectively. The last four rows of Table I summarized the TB parameters for the sucrose analysis.

[0085] COMSOL simulations were performed to identify the effect of the changes in the sucrose concentration’s density and sound velocity in water. The simulations were performed using the experimentally measured acoustic properties of DI water with different sucrose concentrations (ranging from 1-4 g) mixed at room temperature. The speed of sound and density of the sucrose solutions were proportional to the amount of sucrose in the solution. For instance, the highest sucrose concentration (4 g of sucrose in 14 ml) corresponds to a weight percentage of 22.22 %. In the calculations, the acoustic properties were varied with a smaller interval based on the maximum concentration of sucrose to determine the sensitivity of the AS. The sound velocity for the sucrose aqueous solutions was measured using a Fabry -Perot cavity and the time- of-flight measurement technique. The densities of each solution were also calculated, withvalues of 1,024, 1,048, 1,072, and 1,096 kg / m3for 1, 2, 3, and 4 g of sucrose, respectively. The sound velocity was 1,498, 1,513, 1,526, and 1,540 m / s, respectively.

[0086] As described above, the analyte in the pipette is added in the 6thdefect of the upper side while keeping the 6th defect of the bottom. The simulations were performed using the sound velocity and density shown above, considering that the source emits the plane wave being recorded at the receiver. FIG. 6 (pane a) shows a transmission spectrum.

[0087] When the sucrose concentration is increased, the absorption peak redshifts (clear gray arrow) until 10.26 % of the maximum concentration, followed by a broadening of the absorption spectrum (dark gray arrow) at higher concentrations. In order to understand the effect of each parameter, a parametric study was carried out by varying the density at a fixed velocity or by varying the density at a fixed velocity in the medium. FIG. 6 (panel b) exhibits that an increase in the velocity (blue line) induced the redshift at a constant density. However, a blueshift is observed due to an increase in density for a fixed velocity (pink line). Those results indicate that, physically, the increase in the density due to changes in the sucrose concentration has more impact on the observed behavior and also indicates the sensitivity of the proposed AS could decrease for high concentrations.

[0088] As observed, COMSOL results significantly reproduce the finding when considering the density has more physical impact, which increase as the sugar concentration increases. Besides that, the adaptation of the TB theory in defect-based acoustic spectrometer has been previously reported in previous work. It shows the effectiveness of both methods to predict the experimental frequency of the induced resonant modes by the defects and how their shifts when changing the material properties of one the defects used as analyte holder for sensing applications. However, as observed, the incorporation of extra physical information in the TB model is necessary to increase the accurate.

[0089] Conclusion

[0090] A novel ultrasonic MZ-based interferometric technique is used to develop an analyte detection system. The defect-based cavities within the arms of the interferometric waveguide have been used to analyze the physical properties of the microfluidic volume of analytes underwater. The modification of density or viscosity due to the change in concentration of the chemical composition of an analyte can lead to a significant shift in the absorption characteristics of the acoustic wave transmitted through the fluidic channel of the interferometer. Theinterferometric spectrometer shows a high detection sensitivity for lower concentrations of analytes within the acoustic cavity. The absorption characteristics of the analytes within the defect cavity of the periodic phononic crystal can be analyzed using the tight-binding approximation. The density-dependent transmission characteristics of the spectrometer were analyzed due to the modification of the concentration acoustic characteristics of the medium within the finite-element analysis. The MZ-acoustic spectrometer provides a unique technique for analyzing the concentration of solute from a micro-volumetric droplet of an analyte.

[0091] EXAMPLE 2

[0092] Example 2 describes and illustrates an exemplary biomedical acoustic spectrometer. Specifically, Example 2 relates to an acoustic spectrometer configured for Erythrocyte Sedimentation Rate (ESR) testing. Use of inventive aspects of the acoustic spectrometer can generate an ESR test device exhibiting significant increase in sensitivity. In addition, ESR testing using inventive aspects of the acoustic spectrometer can generate ESR analyses and / or test results much faster than the currently used clinical process.

[0093] ESR testing is a blood test commonly used to measure the rate at which red blood cells sediment or settle down within a tube. This sedimentation rate is typically referred to as the “Sed Rate”. The Sed Rate can be used as an indirect measure of inflammation in the body - e.g., a faster Sed Rate can suggest higher levels of inflammation. An increase in inflammation beyond a threshold in can be caused by conditions such as infection, autoimmune disease, cancer, etc. A low Sed Rate can be an indicator of conditions such as polycythemia, hemoglobin abnormalities, etc. Thus, ESR testing can be useful for diagnosing and monitoring conditions associated with inflammation, assessing severity of inflammation in various diseases, monitoring effectiveness of treatment for inflammatory conditions, etc.

[0094] Current methods for measuring Sed Rate involve the Modified Westergren test. FIG. 7 illustrates a typical Modified Westergren test set up, wherein panel a) shows a typical Westergren tube and panel b) shows a typical set up of a Westergren tube on a rack. The Modified Westergren test, however, suffers from a lack of sensitivity and from slow response time. Regarding sensitivity, the Modified Westergren test may not be able to detect elevated ESR in all individuals with inflammatory conditions, especially those with mild or localized inflammation. Regarding slow response time, the Modified Westergren test can take up to one hour to generate results which can render results less useful for monitoring treatmenteffectiveness in some cases - see, e.g., https: / / doi.org / 10.1016ZS 1078-1439(00)00064-8. Moreover, blood clotting becomes an issue at this one-hour processing time, which must be addressed when using the Modified Westergren test.

[0095] FIG. 8A illustrates an exemplary cavity configuration within a defect waveguide based interferometric phononic crystal that can be used for an embodiment of an ESR acoustic spectrometer. FIG. 9 shows an exemplary simulation of acoustic waves propagating through the device of FIG. 8. FIG. 10 shows an actual prototype of the device of FIG. 8.

[0096] With the ESR acoustic spectrometer, acoustic interferometry can be used to detect sedimentation because there is a time-dependent shift in acoustic interference spectrum due to sedimentation. FIG. 11 illustrates optical monitoring of the sedimentation process for two samples. FIG. 11 (panel a) is an actual picture of nanofluids after its preparation within a glass container, for both A (25 nm) and B (60-80 nm) samples. FIG. 11 (panel b) corresponds to the same two samples but after 60 minutes of preparation. FIG. 11 (panel c) is an actual picture of the nanofluids in the pipettes approximately 2 min after the samples were taken. FIG. 11 (panel d) is an actual picture of the nanofluids in the pipettes approximately 60 min after the samples were taken. FIG. 11 (panel e) is an enlarged view of the pipettes after two minutes, and FIG. 11 (panel f) is an enlarged view for the samples after 60 min. FIGS. 12A and 12B show instantaneous spectral shift that had occurred due to sedimentation. This spectral shift profile demonstrates that the device exhibits high sensitivity. Furthermore, only a very small volume of blood is needed to provide adequate analytical results - FIG. 8B shows the defect based waveguide with only a microliter volume of blood.

[0097] FIG. 13 shows a schematic of an exemplary automated ESR acoustic spectrometer system that can be used for ESR testing. The ESR acoustic spectrometer system can include one or more phononic interferometers, each having a phononic structure with a reference arm defined by a defect-based waveguide and a sensing arm defined by a defect-based waveguide. The sensing arm defect-based waveguide can include plural cavities configured to disrupt symmetry of periodicity in the phonic structure. At least one cavity of the plural cavities can be an analyte cavity holder configured to confine blood analyte fluid therein when blood analyte fluid will be introduced into the sensing arm. The acoustic spectrometer can include a phonon generator including a phononic splitter, wherein the phonon generator is configured to generate first phonons to be propagated through the reference arm and second phonons to be propagatedthrough the sensing arm. Again, the phononic interferometer is configured to allow the first phonons to propagate through the reference arm, the second phonons to propagate through the sensing arm, and to combine the first phonons with the second phonons after propagating through the reference arm and the sensing arm, respectively, to generate combined phonons. The acoustic spectrometer includes one or more phonon transducers, each configured to measure phonon energy associated with the combined phonons. A spectrum analyzer is coupled to the phonon transducer(s). With the ESR embodiment, the spectrum analyzer is configured to detect a phase shift between the first phonons and the second phonons of the combined phonons, wherein the spectrum analyzer is calibrated to correlate instantaneous spectral shifts to sedimentation.

[0098] An exemplary method for employing the system can involve:1. Draw 2.0 ml of venous blood.2. Transfer the blood to into a vial containing 0.5 ml of 3.8% sodium citrate solution.3. Circulate the blood to homogenize it using microfluidic pumps.4. It is preferred to not shake the blood, as it will cause frothing.5. Fill the desired defect cavity with blood leaving the others empty.6. Measure the change in the transmission spectrum through the interferometer with and without the RBC.7. Record the change in spectrum with time for 30 minutes.8. Analyze the data after due normalization.

[0099] References

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[0101] It should be understood that the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points. It should also be appreciated that some components, features, and / or configurations may be described in connection with only one particular embodiment, but these same components, features, and / or configurations can beapplied or used with many other embodiments and should be considered applicable to the other embodiments, unless stated otherwise or unless such a component, feature, and / or configuration is technically impossible to use with the other embodiment. Thus, the components, features, and / or configurations of the various embodiments can be combined together in any manner and such combinations are expressly contemplated and disclosed by this statement.

[0102] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible considering the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof.

[0103] It should be understood that modifications to the embodiments disclosed herein can be made to meet a particular set of design criteria. Therefore, while certain exemplary embodiments of the systems, compositions, materials, apparatuses, and methods of using and making the same disclosed herein have been discussed and illustrated, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. An analyzer, comprising: a phononic structure having a defect-based waveguide; wherein the defect-based waveguide includes plural cavities configured to disrupt symmetry of periodicity in the phonic structure; and wherein at least one cavity of the plural cavities is an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the defectbased waveguide.

2. The analyzer of claim 1, wherein: the phononic structure is a sonic crystal, a phononic crystal, or an acoustic metamaterial.

3. The analyzer of claim 1, wherein: the phononic structure is a 2D phononic crystal.

4. The analyzer of claim 1, wherein: when analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide is shifted.

5. A phononic interferometer, comprising: a phononic structure having a reference arm defined by a defect-based waveguide and a sensing arm defined by a defect-based waveguide; wherein: the sensing arm defect-based waveguide includes plural cavities configured to disrupt symmetry of periodicity in the phonic structure; and at least one cavity of the plural cavities is an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm.

6. The phononic interferometer of claim 5, wherein:the phononic structure is a sonic crystal, a phononic crystal, or an acoustic metamaterial.

7. The phononic interferometer of claim 5, wherein: the phononic structure is a 2D phononic crystal.

8. The phononic interferometer of claim 5, wherein: when analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide is shifted.

9. The phononic interferometer of claim 5, further comprising: a detector configured to detect a phase shift between phonons propagating through the reference arm and phonons propagating through the sensing arm.

10. An acoustic spectrometer, comprising: a phononic interferometer, comprising: a phononic structure having a reference arm defined by a defect-based waveguide and a sensing arm defined by a defect-based waveguide; wherein: the sensing arm defect-based waveguide includes plural cavities configured to disrupt symmetry of periodicity in the phonic structure; and at least one cavity of the plural cavities is an analyte cavity holder configured to confine analyte fluid therein when analyte fluid will be introduced into the sensing arm; a phonon generator including a phononic splitter, the phonon generator configured to generate first phonons to be propagated through the reference arm and second phonons to be propagated through the sensing arm, wherein the phononic interferometer is configured to allow the first phonons to propagate through the reference arm, the second phonons to propagate through the sensing arm, and to combine the first phonons with the second phonons after propagating through the reference arm and the sensing arm, respectively, to generate combined phonons;a phonon transducer configured to measure phonon energy associated with the combined phonons; a spectrum analyzer coupled to the phonon transducer, the spectrum analyzer configured to detect a phase shift between the first phonons and the second phonons of the combined phonons.

11. The acoustic spectrometer of claim 10, wherein: the phononic structure is a sonic crystal, a phononic crystal, or an acoustic metamaterial.

12. The acoustic spectrometer of claim 10, wherein: the phononic structure is a 2D phononic crystal.

13. The acoustic spectrometer of claim 10, wherein: when analyte fluid is confined to the analyte cavity holder, phonon propagation characteristics of the defect-based waveguide is shifted.

14. The analyzer of claim 1, wherein: the analyte cavity holder is configured to confine blood analyte.

15. The phononic interferometer of claim 5, wherein: the analyte cavity holder is configured to confine blood analyte.

16. The acoustic spectrometer of claim 10, wherein: the acoustic spectrometer is Erythrocyte Sedimentation Rate (ESR) spectrometer; the analyte cavity holder is configured to confine blood analyte; and the spectrum analyzer is calibrated to correlate instantaneous spectral shifts to sedimentation.

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