Integrated evanescent wave spectrum detection device

Abstract

An embodiment relates to an integrated, compact attenuated total internal reflection (ATR) spectral detection device (200). The spectral detection device (200) includes a substrate (202), a spectrometer (204), and a detector (206). The substrate (202) includes an ATR element (214), a microfluidic channel (208), and a channel interface (216) at a boundary between the ATR element (214) and the microfluidic channel (208) formed therein. The ATR element (214) is configured to receive input light (220) and direct the input light (220) to the channel interface for total internal reflection of the input light (220) at the channel interface. Evanescent waves generated by a sample contained within the microfluidic channel upon total internal reflection of the input light (220) attenuate the output light from the ATR element (214), and the resulting output light (222) may be analyzed using a spectrometer (204) and a detector (206).

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of nonprovisional application No. 17 / 671,983, filed in the U.S. Patent and Trademark Office on February 15, 2022, and provisional application No. 63 / 150,016, filed in the U.S. Patent and Trademark Office on February 16, 2021, the entire contents of which are incorporated by reference into this specification as if fully set forth below and for all applicable purposes.

[0002] The technology described below relates generally to attenuated total internal reflection (ATR) and, more particularly, to mechanisms for integrating ATR elements within spectral sensing devices. [Background technology]

[0003]

[0003] Infrared spectroscopy provides characterization of the vibrational and rotational energy levels of molecules in various materials. When the material is exposed to infrared light, transitions between vibrational levels cause the absorption of photons at specific wavelengths. In general, there are two mechanisms for performing spectral measurements; transmission mode, where infrared light is passed through a specimen, or reflection mode, where infrared light is reflected from the specimen.

[0004]

[0004] Attenuated total internal reflection (ATR) spectroscopy is a type of reflection coupling that relies on the internal reflection of light inside a high refractive index material while the sample is in close contact with the material. ATR spectroscopy allows for the spectral analysis of any type of sample with minimal sample preparation. ATR has been used as an effective method to analyze fluid and solid samples based on the phenomenon of total internal reflection of light at the boundary between two media. A high refractive index material such as zinc selenide, germanium or silicon, usually called an ATR crystal, ATR internal reflection element (IRE) or ATR element, is illuminated with an IR light source while the sample covers the ATR crystal and is in close contact with the ATR crystal. If the angle of the input light is greater than the critical angle at the boundary between the ATR crystal and the sample, the light is totally internally reflected and a special type of electromagnetic wave called an evanescent wave is formed on the sample side. The sample absorbs a part of the intensity of the evanescent wave due to molecular vibrations at a certain wavelength. Thus, the intensity of the reflected light is attenuated compared to the intensity of the incident light. The output light of the crystal may then be coupled into a Fourier Transform Infrared (FTIR) system, which may be based on a Michelson interferometer, as an example of a spectroscopic technique, and then coupled to a broadband IR detector to analyze the sample spectrum.

[0005]

[0005] ATR techniques are classified into macro-ATR and micro-ATR techniques depending on the size of the IRE. In macro-ATR, commercially available ATR crystals of various large sizes are used depending on the required field of view and spatial resolution. Furthermore, macro-ATR techniques have been implemented as an analytical tool for liquids in microfluidic chips, where the liquid flows in micron-sized channels. One example of macro-ATR technique includes a microfluidic device built on top of a commercially available polished ATR IRE using a polydimethylsiloxane (PDMS) device.

[0006]

[0006] To avoid the high cost of IRE and the need for mechanical polishing, microfabricated elements fabricated on silicon wafers have begun to replace the bulky crystals, called micro-ATR. Anisotropic KOH etching of silicon wafers is used to provide an inclined optical surface for light interaction. Then, a glass wafer with microfabricated channels is bonded on top of the wafer, or a fluid pattern is created on this groove-free surface. This allows the combination of ATR spectroscopy with microfluidics, which has various applications in the fields of biology and chemistry. However, the sample preparation and measurement steps become more complicated, since three separate systems, the microfluidic chip, the micro-ATR IRE, and the optical coupling system of the spectrometer, need to be aligned together. Summary of the Invention

[0007]

[0007] The following presents a summary of one or more aspects of the present disclosure in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, nor is it intended to identify key or critical elements of all aspects of the disclosure or to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure as a prelude to the more detailed description that is presented later.

[0008]

[0008] In one example, an integrated spectral detection device is disclosed. The integrated spectral detection device includes a first substrate including an attenuated total internal reflection (ATR) element, a microfluidic channel, and a channel interface corresponding to a boundary between the ATR element and the microfluidic channel formed therein. The ATR element is configured to receive input light and generate output light based on total internal reflection of the input light at the channel interface. The output light is attenuated by an evanescent wave generated by a sample contained within the microfluidic channel based on total internal reflection of the input light. The integrated spectral detection device further includes a spectrometer configured to generate an interference beam corresponding to the input light or an interference beam based on the output light, and a detector configured to detect a spectrum of the interference beam or the output light.

[0009]

[0009] These and other aspects of the present invention will be more fully understood by considering the following detailed description. Other aspects, features and embodiments of the present invention will become apparent to those skilled in the art by considering the following description of certain exemplary embodiments of the present invention in conjunction with the accompanying drawings. Although the features of the present invention may be described with respect to the following specific embodiments and drawings, all embodiments of the present invention may include one or more of the advantageous features described herein. In other words, while one or more embodiments may be described as having a particular advantageous feature, one or more of such features may be used in accordance with various embodiments of the present invention described herein. Similarly, although an exemplary embodiment may be described below as an embodiment of a device, system or method, it should be understood that such exemplary embodiments may be implemented in various devices, systems and methods. [Brief description of the drawings]

[0010] [Figure 1]

[0010] FIG. 1 illustrates a spectrometer according to an embodiment. [Figure 2A]

[0011] FIG. 1 illustrates an example of an integrated spectral sensing device. [Figure 2B]

[0012] FIG. 2 is a plan view of another example of an integrated spectral sensing device according to an embodiment. [Diagram 3]

[0013] FIG. 1 illustrates an example of a multi-substrate integrated spectral detection device according to an embodiment. [Figure 4]

[0014] FIG. 2 illustrates another example of a multi-substrate integrated spectral sensing device according to an embodiment. [Diagram 5]

[0015] FIG. 2 illustrates another example of a multi-substrate integrated spectral sensing device according to an embodiment. [Figure 6]

[0016] FIG. 2 illustrates another example of a multi-substrate integrated spectral sensing device according to an embodiment. [Figure 7A]

[0017] FIG. 2 illustrates an example of a compact ATR spectrometer of an integrated spectral detection device according to an embodiment. [Figure 7B]

[0017] FIG. 1 illustrates an example of a compact ATR spectrometer of an integrated spectral detection device according to one embodiment. [Figure 8]

[0018] FIG. 2 illustrates another example of a compact ATR spectrometer of an integrated spectral detection device according to an embodiment. [Figure 9]

[0019] FIG. 1 illustrates an example of an integrated spectral detection device including a miniature ATR spectrometer, according to an embodiment. [Figure 10]

[0020] FIG. 2 is a diagram showing an example of an ATR element design according to an embodiment. [Figure 11]

[0021] FIG. 13 illustrates another example of an ATR element design according to an embodiment. [Figure 12A]

[0022] FIG. 13 illustrates another example of an ATR element design according to an embodiment. [Figure 12B]

[0022] FIG. 1 is a diagram showing another example of an ATR element design according to an embodiment. [Figure 13]

[0023] FIG. 13 illustrates another example of an ATR element design according to an embodiment. [Figure 14]

[0024] FIG. 13 illustrates another example of an ATR element design according to an embodiment. [Figure 15]

[0025] FIG. 13 illustrates another example of an ATR element design according to an embodiment. [Figure 16]

[0026] FIG. 13 illustrates another example of an ATR element design according to an embodiment. [Figure 17]

[0027] FIG. 1 shows another example of an ATR element design based on field-flow fractionation (FFF) according to an embodiment. [Figure 18]

[0028] FIG. 1 illustrates another example of an ATR element design based on dielectrophoresis (DEP), according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0029] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that the concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0012]

[0030] Various aspects of the present disclosure relate to an integrated and compact ATR spectral detection device. The spectral detection device includes a substrate, a spectrometer, and a detector. The substrate includes an ATR element, a microfluidic channel, and a channel interface at a boundary between the ATR element and the microfluidic channel formed therein. The ATR element is configured to receive input light and direct the input light to the channel interface for total internal reflection of the input light at the channel interface. An evanescent wave may then be generated by a sample contained within the microfluidic channel based on total internal reflection of the input light. The evanescent wave attenuates the light output from the ATR element, and the resulting output light may be analyzed using the spectrometer and the detector.

[0013]

[0031] The spectrometer core can be based on FTIR spectroscopy, tunable filters, diffraction gratings, or other suitable spectroscopic techniques for selectively measuring different wavelengths of the light spectrum. In one example, an ATR IRE (also referred to herein as an ATR crystal or ATR element) can be integrated with an FTIR-based spectrometer that may include, for example, a microelectromechanical system (MEMS) Michelson interferometer and a reflective micro-optical element (light redirecting element) for coupling light between the spectrometer core.

[0014]

[0032] In an integrated spectral detection device, the light propagates inside the ATR element in-plane relative to the spectrometer, either in a separate substrate of the spectrometer or in the same substrate. In such an in-plane configuration, the ATR IRE element may be microfabricated, for example using deep reactive ion etching (DRIE), so that the light travels parallel to the substrate, allowing a high level of monolithic integration of all ATR and spectrometer elements in a single compact module. Furthermore, the in-plane ATR allows the creation of an IRE with a desired shape and dimensions depending on the sample being measured. For example, the angle of incidence and the number of reflections may be adapted to the design.

[0015]

[0033] In one example, the integrated spectral detection device includes three substrates, one for a spectrometer (e.g., a MEMS interferometer), one for a light redirecting element, and a third for an ATR crystal (ATR element), and the three substrates are bonded together into a single module. In another example, the ATR element and the spectrometer (e.g., a MEMS interferometer) are formed in the same substrate (e.g., a silicon substrate) and bonded to another substrate that includes a light redirecting element. The substrate containing the monolithically integrated ATR element / MEMS interferometer may further include guide structures in the silicon to guide light to / from a microfluidic channel through which liquid flows.

[0016]

[0034] Unlike conventional ATR element designs, in various embodiments of the present disclosure, the sample fluid flows between input and output ports adjacent to the ATR IRE on the same substrate, avoiding the difficult step of bonding and aligning two separate wafers together. Taking advantage of the silicon transmission characteristics in the IR range and free space coupling to the MEMS chip, both designs presented herein can be easily used to measure the ATR signal and analyze materials in the mid-infrared (MIR) range. Furthermore, the integration of the microfluidic channel and the microspectrometer into a single module realizes an inexpensive and simple device for analyzing samples in ATR sampling mode. Various particle separation and sorting techniques may be further added to the microfluidic device to analyze microparticles and contaminants using the integrated spectral detection device.

[0017]

[0035] FIG 1 illustrates a spectrometer 100 according to an embodiment. The spectrometer 100 may be, for example, a Fourier transform infrared (FTIR) spectrometer. In the example shown in FIG 1, the spectrometer 100 is a Michelson FTIR interferometer. In other examples, the spectrometer may include an FTIR Fabry-Perot interferometer.

[0018]

[0036] FTIR spectrometers measure a single beam spectrum (power spectral density (PSD)), the intensity of which is proportional to the power of the radiation reaching the detector. To measure the absorbance of a sample, a background spectrum (i.e., the single beam spectrum in the absence of sample) is first measured to compensate for the transfer function of the instrument. A single beam spectrum of light transmitted through or reflected from the sample may then be measured. The absorbance of a sample may be calculated from the transmittance, reflectance or semi-reflectance of the sample. For example, the absorbance of a sample may be calculated as the ratio of the spectrum of transmitted, reflected or semi-reflected light from the sample to the background spectrum.

[0019]

[0037] Interferometer 100 includes a fixed mirror 104, a movable mirror 106, a beam splitter 110, and a detector 112 (e.g., a photodetector). A light source 102 associated with spectrometer 100 is configured to emit an input beam and direct the input beam to beam splitter 110. Light source 102 may include, for example, a laser source, one or more broadband thermal radiation sources, or a quantum source having an array of light emitting devices covering the wavelength range of interest.

[0020]

[0038] The beam splitter 110 is configured to split the input beam into two beams. One beam is reflected from the fixed mirror 104 back towards the beam splitter 110, while the other beam is reflected from the movable mirror 106 back towards the beam splitter 110. The movable mirror 106 may be coupled to an actuator 108 that displaces the movable mirror 106 to a desired position to reflect the beam. An optical path length difference (OPD) is then created between the reflected beams that is substantially equal to twice the displacement of the mirror 106. In some examples, the actuator 108 may include a microelectromechanical system (MEMS) actuator, a thermal actuator, or other types of actuators.

[0021]

[0039] The reflected beams interfere at the beam splitter 110 to produce an interference beam (e.g., an interference pattern) that allows the temporal coherence of light to be measured at each different optical path difference (OPD) provided by the movable mirror 106. In one example, a signal corresponding to the interference beam may be directed to a sample (not shown), and the output light (scattered light) from the sample may be detected and measured by a detector 112 at many discrete positions of the movable mirror 106 to create an interferogram. In another example, the input beam may be directed to a sample prior to input to the interferometer 100. In one example, the detector 112 may include a detector array or a single pixel detector. The interferogram data versus OPD may then be input to a processor (not shown for simplicity). A spectrum may then be obtained, for example, using a Fourier transform performed by the processor.

[0022]

[0040] In one example, the interferometer 100 may be implemented as a MEMS interferometer 100a (e.g., a MEMS chip). The MEMS chip 100a may be mounted on a printed circuit board (PCB) 116, which may include, for example, one or more processors, memory devices, buses, and / or other components. As used herein, the term MEMS refers to the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication techniques. For example, microelectronics are typically fabricated using integrated circuit (IC) processes, while micromechanical components are fabricated using compatible micromachining processes that selectively etch away portions of silicon wafers or add new structural layers to form mechanical and electromechanical components. One example of a MEMS element is a micro-optical component with a dielectric or metallized surface that operates in a reflective or refractive mode. Other examples of MEMS elements include actuators, detector grooves, and fiber grooves.

[0023]

[0041] In the example shown in FIG. 1, the MEMS interferometer 100a may include a fixed mirror 104, a movable mirror 106, a beam splitter 110, and a MEMS actuator 108 for movably controlling the movable mirror 106. Additionally, the MEMS interferometer 100a may include a fiber 114 for directing an input beam to the beam splitter 110 and an output beam from the beam splitter 110 to a detector (e.g., detector 112). In one example, the MEMS interferometer 100a may be fabricated using a deep reactive ion etching (DRIE) process on a silicon-on-insulator (SOI) wafer to fabricate micro-optical components and other MEMS elements capable of processing a free-space optical beam propagating parallel to the SOI substrate. For example, an electromechanical design may be printed on a mask, and the mask may be used to photolithographically pattern the design on a silicon or SOI wafer. The pattern may then be etched using a batch process (e.g., by DRIE), and the resulting chip (e.g., MEMS chip 100a) may be diced and packaged (e.g., attached to PCB 116).

[0024]

[0042] For example, the beam splitter 110 may be a silicon / air interface beam splitter (e.g., a half-plane beam splitter) positioned at an angle (e.g., 45 degrees) from the input beam. The input beam may then be split into two beams L1 and L2, where L1 propagates in air towards the movable mirror 106 and L2 propagates in silicon towards the fixed mirror 104. Here, L1 results from partial reflection of the input beam from the half-plane beam splitter 110 and thus has an angle of reflection equal to the beam incidence angle. L2 results from partial transmission of the input beam through the half-plane beam splitter 110 and propagates in silicon at an angle determined by Snell's law. In one example, the fixed mirror 104 and the movable mirror 106 are metal mirrors and a selective metallization method (e.g., using a shadow mask during the metallization step) is used to protect the beam splitter 110. In another example, the mirrors 104 and 106 are vertical Bragg mirrors, which can be realized using, for example, DRIE.

[0025]

[0043] In one example, the MEMS actuator 108 may be an electrostatic actuator formed from a comb drive and a spring. For example, applying a voltage to the comb drive creates a potential difference across the actuator 108, which induces a capacitance in the actuator 108, generating a drive force and a restoring force from the spring, thereby displacing the moveable mirror 106 to a desired position for reflecting the beam back towards the beam splitter 110.

[0026]

[0044] In various embodiments of the present disclosure, the spectrometer 100 shown in FIG. 1 or other suitable spectral detection unit may be incorporated into an integrated evanescent wave spectral detection device. FIG. 2A illustrates an example of an integrated spectral detection device 200 according to an embodiment. The integrated spectral detection device 200 includes a substrate 202, such as a silicon substrate or an SOI substrate, a spectrometer 204 (e.g., a MEMS interferometer shown in FIG. 1), and a detector 206. The substrate 202 includes an ATR element 214 and a microfluidic channel 208 formed in the substrate 202 using, for example, a DRIE process. The ATR element 214 may correspond to or include a waveguide for passing light therethrough. The microfluidic channel 208 includes a sample 210 (e.g., a fluid) that flows through the microfluidic channel 208 between an input microfluidic port 212 and an output microfluidic port 212. The sample 210 flows adjacent to a boundary 216 between the microfluidic channel 208 and the ATR element 214. The boundary 216 corresponds to a channel interface between the ATR element 214 and the microfluidic channel 208 and may be formed by a surface of the ATR element 214 with which the sample 210 is in contact. For example, the boundary or channel interface 216 may correspond to an inclined or vertical surface of the ATR element 214 that further serves as an inner surface of the microfluidic channel 208. In examples where the substrate 202 is a silicon or SOI substrate, the channel interface 216 may correspond to a silicon-air (Si-air) interface that forms a silicon-sample (Si-sample) interface where the sample is inserted.

[0027]

[0045] The light source 218 (e.g., an external IR blackbody light source) is configured to generate input light 220 (e.g., IR or NIR light). The input light 220 is directed to the ATR element 214 in the substrate 202. The ATR element 214 may be a single reflection ATR element as shown in FIG. 2A or may be a multiple reflection ATR element. The ATR element 214 is designed to generate total internal reflection of the input light 220 at the channel interface 216. For example, the ATR element 214 may have a size (dimension, thickness, etc.) and shape (e.g., V-shaped input interface 226 and output interface 228) configured to generate an angle of the input light 220 that is greater than the critical angle at the boundary 216 between the ATR element 214 and the sample 210. The resulting evanescent wave generated in the sample 210 based on the total internal reflection of the input light 220 attenuates the input light 220 to generate output light 222 that can be input to the spectrometer 204. In some examples, the integrated spectral detection device may further include one or more optical elements, such as light focusing elements (e.g., lenses) and / or light redirecting elements (e.g., mirrors or other reflectors) for directing light to the ATR element 214 and / or from the ATR element 214 to the spectrometer 204. The spectrometer 204 is configured to generate an interference beam (interference pattern) 224 of the output light 222 and provide the interference beam 224 to the detector 206 for spectral analysis.

[0028]

[0046] In one example, the spectrometer 204 may be disposed in a position before the ATR element 214. In this example, the spectrometer 204 may be configured to receive input light 220 from the light source 218, generate an interference beam 224 from the input light 220, and direct the interference beam 224 to the ATR element 214. Output light 222 from the ATR element 214 may then be directed to the detector 206.

[0029]

[0047] 2B is a plan view of another example of an integrated spectral detection device 250 according to an embodiment. The integrated spectral detection device 250 includes a substrate 252, a spectrometer 254 (e.g., a MEMS interferometer as shown in FIG. 1), and a detector 256. The substrate 252 includes an ATR element 262 and a microfluidic channel 258 formed within the substrate 252. The ATR element 262 may correspond to or include a waveguide. The microfluidic channel 258 includes a sample 260 (e.g., a fluid) flowing through the microfluidic channel 258 adjacent to a boundary 264 (e.g., a channel interface) between the microfluidic channel 258 and the ATR element 262.

[0030]

[0048] The light source 256 (e.g., an external IR blackbody light source) is configured to generate input light 270 (e.g., IR or NIR light) and direct the input light 270 to an optical component (e.g., a lens) 268 that couples the input light 270 into the ATR element 262. In the example shown in FIG. 2B, the ATR element 262 is a multi-reflection ATR element. The ATR element 262 is designed to generate total internal reflection of the input light 270 at a channel interface 264. For example, the ATR element 264 is designed to generate a total internal reflection of the input light 270 at a critical angle θ of the channel interface 264 between the ATR element 262 and the sample 260. C The total internal reflection of the input light 270 may be designed to produce an angle θ of the input light 270 that is greater than θ=θ. The total internal reflection of the input light 270 forms an evanescent wave 272 on the sample side of the boundary 262. The sample 260 absorbs a portion of the intensity of the evanescent wave 272 due to molecular vibrations at a particular wavelength. Thus, the intensity of the reflected light (the total internally reflected light) is attenuated compared to the incident intensity. Output light 274, which is attenuated relative to the input light 270 based on the total internal reflection of the input light 270 and the evanescent wave generated by the sample 260, is coupled into the spectrometer 254 via a light redirecting element (e.g., a mirror) 276.

[0031]

[0049] The spectrometer 254 shown in FIG. 2B is a MEMS interferometer including a beam splitter 278, a movable mirror 280, and a fixed mirror 282. The beam splitter 278 is configured to split the output light 274 into two beams. One beam is reflected from the fixed mirror 282 back towards the beam splitter 278, while the other beam is reflected from the movable mirror 280 back towards the beam splitter 278. The movable mirror 280 may be coupled to an actuator (not shown) that displaces the movable mirror 280 to a desired position to reflect the beam. An optical path length difference (OPD) is then generated between the reflected beams that is substantially equal to twice the displacement of the mirror 280. The reflected beams interfere at the beam splitter 278 to generate an interference beam (e.g., interference pattern) 284, allowing the temporal coherence of the output light 274 to be measured at each different optical path difference (OPD) provided by the movable mirror 280. The interference beam (interference pattern) 284 may be detected and measured by detector 256 at many discrete positions of the moveable mirror 280 to produce an interferogram representing the spectrum of the sample 260 .

[0032]

[0050] FIG. 3 illustrates an example of a multi-substrate integrated spectral sensing device 300 according to an embodiment. In the example illustrated in FIG. 3, the integrated spectral sensing device 300 includes three substrates 302, 304, and 306. The first substrate 302 is disposed in a first plane parallel to a second plane of the third substrate 306. The integrated spectral sensing device 300 may further include a package substrate 308. The third substrate 306 may be disposed (e.g., bonded) on the package substrate 308. Furthermore, the second substrate 304 may be disposed on the third substrate 306 and bonded to the package substrate 308 at each end of the second substrate 304. A detector 318 may further be disposed on the package substrate 308. Each of the substrates 302, 306, and 308 may be, for example, a silicon substrate or an SOI substrate. In an example, the second substrate 304 may be a plastic substrate or a glass substrate formed using an injection molding optical technique.

[0033]

[0051] The first substrate 302 includes an ATR element 310 and two opposing microfluidic channels 312a and 312b. The ATR element 310 and the microfluidic channels 312a and 312b are formed in the first substrate 302, for example, via a DRIE process. The ATR element 310 may correspond to or include a waveguide. Each microfluidic channel 312a and 312b includes a sample (e.g., a fluid) flowing through the microfluidic channel 312a and 312b adjacent to a respective boundary 314a and 314b (e.g., a channel interface) between the respective microfluidic channel 312a and 312b and the ATR element 310. Each channel interface 314a and 314b may correspond to a deep etched vertical surface of the first substrate 302. For example, each channel interface 312a and 312b may correspond to a silicon-air (Si-air) interface that forms a silicon-sample (Si-sample) interface into which the sample is inserted. The ATR element 310, the first microfluidic channel 312a and the second microfluidic channel 312b are configured such that total internal reflection of light occurs within the ATR element 310 between the first channel interface 314a and the second channel interface 314b.

[0034]

[0052] The second substrate 304 includes one or more light redirecting elements 316 and 320 formed therein. For example, the light redirecting elements 316 and 320 may be curved reflectors (e.g., microreflectors or micromirrors). In one example, the light redirecting elements 316 and 320 may be fabricated within a molded part of the second substrate 304 with an aluminum metal coating to improve its reflectivity.

[0035]

[0053] The third substrate 306 includes a spectrometer 322 formed therein, for example, by a DRIE process. The spectrometer 322 may include a beam splitter 324, a fixed mirror 326, and a moveable mirror 328. The moveable mirror 328 may be coupled to an actuator 330, such as a MEMS electrostatic actuator.

[0036]

[0054] In the example shown in FIG. 3, input light 332 from a light source (not shown) is input into the ATR element 310 on the first substrate 302. For example, the ATR element 310 may include a V-shaped input interface configured to generate an angle of the input light 332 on the channel interface 314b of the microfluidic channel 312b that is greater than a critical angle for generating total internal reflection of the input light 332 at the channel interface 314b. The input light 332 is then totally reflected between the channel interfaces 314a and 314b, where the input light 332 is attenuated by respective evanescent waves formed within the sample contained in each of the microfluidic channels 312a and 312b. The attenuated input light is output from the ATR element 310 as output light 334. For example, the ATR element 310 may include a V-shaped output interface configured to facilitate transmission of the output light 334 reflected from the channel interface 314b of the microfluidic channel 312b.

[0037]

[0055] The output light 334 may be redirected by the optical element 315 (e.g., a tilted or curved reflector) from an in-plane direction relative to the plane of the first substrate 302 to an out-of-plane direction relative to the first plane of the first substrate 302. Thus, the optical element 315 receives the output light propagating parallel to the plane of the first substrate 302 and reflects the output light 334 90 degrees to facilitate propagation of the output light 334 perpendicular to the plane of the first substrate 302 towards the light redirecting element 316. The optical element 315 may be formed as part of the second substrate 302 or may be an external component (the latter is shown). The light redirecting element 316 receives the output light 334 propagating out-of-plane relative to the plane of the first substrate 302 and reflects the output light a further 90 degrees towards the spectrometer 322 to facilitate propagation of the output light 334 in-plane relative to the plane of the third substrate 306.

[0038]

[0056] The output light 334 is input to a beam splitter 324 of the spectrometer 322. The beam splitter 324 is configured to split the output light 334 into two beams. One beam is reflected from a fixed mirror 326 back towards the beam splitter 324, while the other beam is reflected from a movable mirror 328 back towards the beam splitter 324. The movable mirror 328 may be displaced by an actuator 330 to a desired position to reflect the beam. An optical path length difference (OPD) is then generated between the reflected beams that is substantially equal to twice the displacement of the movable mirror 328. The reflected beams interfere at the beam splitter 324 to generate an interference beam (e.g., an interference pattern) 336, allowing the temporal coherence of the output light 334 to be measured at each different optical path difference (OPD) provided by the movable mirror 328. The interference beam (interference pattern) 336 may then be output by the spectrometer 322 and redirected by the light redirecting element 320 towards the detector 318 to obtain a spectrum of the sample in the microfluidic channels 312a and 312b. For example, the light redirecting element 320 may be a curved reflector configured to focus the interference beam 336 onto the active area of ​​the detector 318.

[0039]

[0057] The design of the integrated spectral detection device 300 shown in FIG. 3 is a reflector-based design, rather than a lens-based design, which reduces chromatic aberration of the integrated spectral detection device 300. Furthermore, the transmission properties of silicon allow the integrated spectral detection device 300 to operate in an ultra-wideband spectral range that is limited only by the silicon crystal and detector materials. Furthermore, the integrated spectral detection device 300 is shown integrated into a single package (e.g., using a packaging substrate 308) to produce an inexpensive and simple device. Furthermore, the crystal length (e.g., the length of the first substrate 302 containing the ATR element 310) is shown to be on the same order as the optical mold design dimensions of the second substrate 304 to facilitate packaging. However, in other examples, longer or shorter crystal designs may be used depending on the target number of internal reflections.

[0040]

[0058] FIG. 4 illustrates another example of a multi-substrate integrated spectral sensing device 400 according to an embodiment. In the example illustrated in FIG. 4, the integrated spectral sensing device 400 includes three substrates 402, 404, and 406. The first substrate 402 is disposed in a first plane parallel to a second plane of the third substrate 406. The integrated spectral sensing device 400 may further include a package substrate 408. The third substrate 406 may be disposed (e.g., bonded) on the package substrate 408. Furthermore, the second substrate 404 may be disposed on the third substrate 406 and bonded to the package substrate 408 at each end of the second substrate 404. A detector 418 may further be disposed on the package substrate 408. Each of the substrates 402, 406, and 408 may be, for example, a silicon substrate or an SOI substrate. In an example, the second substrate 404 may be a plastic substrate or a glass substrate formed using an injection molding optical technique.

[0041]

[0059] The first substrate 402 includes an ATR element 410 and two opposing microfluidic channels 412a and 412b. The ATR element 410 and the microfluidic channels 412a and 412b are formed in the first substrate 402, for example, via a DRIE process. Each microfluidic channel 412a and 412b includes a sample (e.g., a fluid) that flows through the microfluidic channels 412a and 412b adjacent to a respective boundary (e.g., a channel interface similar to the channel interface shown in FIG. 3) between the respective microfluidic channels 412a and 412b and the ATR element 410.

[0042]

[0060] The second substrate 404 includes one or more light redirecting elements 416 and 420 formed therein. For example, the light redirecting elements 416 and 420 may be curved reflectors (e.g., microreflectors or micromirrors). In one example, the light redirecting elements 416 and 420 may be fabricated into a molded part of the second substrate 404 with an aluminum metal coating to improve its reflectivity. The third substrate 406 includes a spectrometer 428 formed therein, for example, via a DRIE process.

[0043]

[0061] In the example shown in Figure 4, input light 422 from a light source (not shown) is input into an ATR element 410 on a first substrate 402. For example, the ATR element 410 may include a V-shaped input interface configured to generate an angle of the input light 422 greater than a critical angle to generate total internal reflection of the input light 422 through the ATR element 410 between the microfluidic channels 412a and 412b. The input light 422 is attenuated by respective evanescent waves formed within a sample contained within each of the microfluidic channels 412a and 412b. The attenuated input light is then output from the ATR element 410 as output light 424.

[0044]

[0062] 4, the ATR element 410 includes an angled surface 414 for coupling the output light 424 out-of-plane towards the light redirecting element 416. For example, the angled surface 414 may couple the output light 424 to the light redirecting element 416 in an out-of-plane direction relative to the plane of the ATR element 410 (e.g., the plane of the first substrate 402). In one example, the angled surface 414 may be anisotropically etched into the first substrate 402 using, for example, a KOH etch. The light redirecting element 416 receives the output light 424 propagating out-of-plane relative to the plane of the first substrate 402 and redirects the output light 424 (e.g., reflects the output light 90 degrees) towards a spectrometer 428 of the third substrate 406 to facilitate propagation of the output light 424 in-plane relative to the plane of the third substrate 406.

[0045]

[0063] The spectrometer 428 generates an interference beam (interference pattern) 426 based on the output light 424, which is redirected by the light redirecting element 420 towards the detector 418 to obtain the spectrum of the sample in the microfluidic channels 412a and 412b. For example, the light redirecting element 420 may be a curved reflector configured to focus the interference beam 426 onto the active area of ​​the detector 418.

[0046]

[0064] FIG. 5 illustrates another example of a multi-substrate integrated spectral sensing device 500 according to an embodiment. In the example illustrated in FIG. 5, the integrated spectral sensing device 500 includes three substrates 502, 504, and 506. The first substrate 502 is disposed in a first plane parallel to a second plane of the third substrate 506. The integrated spectral sensing device 500 may further include a package substrate 508. The third substrate 506 may be disposed on the package substrate 508 (e.g., bonded to the package substrate 508). Furthermore, the second substrate 504 may be disposed on the third substrate 506 and bonded to the package substrate 508 at each end of the second substrate 504. The detector 518 may further be disposed on the package substrate 508. Each of the substrates 502, 506, and 508 may be, for example, a silicon substrate or an SOI substrate. In an example, the second substrate 504 may be a plastic substrate or a glass substrate formed using an injection molding optical technique.

[0047]

[0065] The first substrate 502 includes an ATR element 510 and two opposing microfluidic channels 512a and 512b. The ATR element 510 and the microfluidic channels 512a and 512b are formed in the first substrate 502, for example, via a DRIE process. Each microfluidic channel 512a and 512b includes a sample flowing through the microfluidic channel 512a and 512b adjacent to a respective boundary between the respective microfluidic channel 512a and 512b and the ATR element 510 (e.g., a channel interface similar to the channel interface shown in FIG. 3).

[0048]

[0066] The second substrate 504 includes one or more light redirecting elements 514, 516, and 520 formed therein. For example, the light redirecting elements 514, 516, and 520 may be curved reflectors (e.g., microreflectors or micromirrors). In one example, the light redirecting elements 514, 516, and 520 may be fabricated into a molded part of the second substrate 504 with an aluminum metal coating to improve its reflectivity. The third substrate 506 includes a spectrometer 528 formed therein, for example, via a DRIE process.

[0049]

[0067] 5, input light 522 from a light source (not shown) is input into an ATR element 510 on a first substrate 502. For example, the ATR element 510 may include a V-shaped input interface configured to generate an angle of the input light 522 greater than a critical angle to generate total internal reflection of the input light 522 through the ATR element 510 between microfluidic channels 512a and 512b. The input light 522 is attenuated by respective evanescent waves formed within a sample contained within each of the microfluidic channels 512a and 512b. The attenuated input light is then output from the ATR element 510 as output light 524.

[0050]

[0068] 5, the output light 524 is directed to the light redirecting element 514 for out-of-plane coupling to the light redirecting element 516. For example, the light redirecting element 514 is configured to receive the output light 524 at a first plane of the ATR element 510 (e.g., the first substrate 502) and reflect (redirect) the output light 524 toward the light redirecting element 516 in an out-of-plane direction relative to the first plane. The light redirecting element 516 receives the output light 524 propagating out-of-plane relative to the plane of the first substrate 502 and directs the output light 524 from the out-of-plane direction to an in-plane direction relative to a second plane of the third substrate 506 (e.g., reflects the output light 90 degrees) toward the spectrometer 528.

[0051]

[0069] The spectrometer 528 generates an interference beam (interference pattern) 526 based on the output light 524, which is redirected by the light redirecting element 520 towards the detector 518 to obtain the spectrum of the sample in the microfluidic channels 512a and 512b. For example, the light redirecting element 520 may be a curved reflector configured to focus the interference beam 526 onto the active area of ​​the detector 518.

[0052]

[0070] FIG. 6 illustrates another example of a multi-substrate integrated spectral sensing device 600 according to an embodiment. In the example illustrated in FIG. 6, the integrated spectral sensing device 600 also includes three substrates (e.g., a first substrate 602, a second substrate 604, and a third substrate 606). However, the first substrate 602 and the third substrate 606 are disposed in the same plane. The integrated spectral sensing device 600 may further include a package substrate 608. The first substrate 602 and the third substrate 606 may be disposed on the package substrate 608 (e.g., bonded to the package substrate 608). Furthermore, the second substrate 604 may be disposed on the first substrate 602 and the third substrate 606, and may be bonded to the package substrate 608 at each end of the second substrate 604. The detector 618 may further be disposed on the package substrate 608. Each of the substrates 602, 606, and 608 may be, for example, a silicon substrate or an SOI substrate. In one example, the second substrate 604 may be a plastic or glass substrate formed using injection molding optical techniques.

[0053]

[0071] The first substrate 602 includes an ATR element 610 and two opposing microfluidic channels 612a and 612b. The ATR element 610 and the microfluidic channels 612a and 612b are formed in the first substrate 602, for example, via a DRIE process. Each microfluidic channel 612a and 612b includes a sample (e.g., a fluid) that flows through the microfluidic channel 612a and 612b adjacent to a respective boundary (e.g., a channel interface similar to the channel interface shown in FIG. 3) between the respective microfluidic channel 612a and 612b and the ATR element 610.

[0054]

[0072] The second substrate 604 includes one or more light redirecting elements 616 and 620 formed therein. For example, the light redirecting elements 616 and 620 may be curved reflectors (e.g., microreflectors or micromirrors). In one example, the light redirecting elements 616 and 620 may be fabricated into a molded part of the second substrate 604 with an aluminum metal coating to improve its reflectivity. The third substrate 606 includes a spectrometer 628 formed therein, for example, via a DRIE process.

[0055]

[0073] In the example shown in FIG. 6, input light 622 from a light source (not shown) is input to the integrated spectral detection device 600 in an out-of-plane direction relative to the plane of the first substrate 602 and the third substrate 606 toward the light redirecting element 616. The light redirecting element 616 is configured to receive the input light 622 in an out-of-plane direction and direct the input light 622 toward the first substrate 602 (e.g., redirect / reflect the input light 622 90 degrees toward the first substrate 602). The input light 622 may be incident on the ATR element 610 at an angle of incidence greater than a critical angle to generate total internal reflection of the input light 622 through the ATR element 610 between the microfluidic channels 612a and 612b. The input light 622 is attenuated by respective evanescent waves formed within a sample contained within each of the microfluidic channels 612a and 612b. The attenuated input light is then output from the ATR element 610 as output light 624 towards a spectrometer 628 on the third substrate 606 .

[0056]

[0074] The spectrometer 628 generates an interference beam (interference pattern) 626 based on the output light 624, which is redirected by the light redirecting element 620 towards the detector 618 to obtain the spectrum of the sample in the microfluidic channels 612a and 612b. For example, the light redirecting element 620 may be a curved reflector configured to focus the interference beam 626 onto the active area of ​​the detector 618.

[0057]

[0075] 7A and 7B are diagrams illustrating an example of a compact ATR spectrometer 700 of an integrated spectral detection device according to an embodiment. In the example illustrated in FIGS. 7A and 7B, the compact ATR spectrometer 700 includes a spectrometer 704, an ATR element 706, and a microfluidic channel 708 integrated on the same substrate 702. The substrate 702 may be, for example, a silicon substrate or an SOI substrate. The ATR element 706 may correspond to or include a waveguide for passing light. The microfluidic channel 708 includes a sample 712 (e.g., a fluid) that flows through the microfluidic channel 708 between an input microfluidic port 710 and an output microfluidic port 710. The sample 712 flows adjacent to a boundary 730 between the microfluidic channel 708 and the ATR element 706. The boundary 730 corresponds to a channel interface between the ATR element 706 and the microfluidic channel 708, and may be formed by a surface of the ATR element 706 that the sample 712 contacts. For example, the boundary or channel interface 730 may correspond to a vertical surface of the ATR element 706 etched into the substrate 702 (e.g., via a DRIE process), which further serves as the inner surface of the microfluidic channel 708. Thus, the channel interface 730 corresponds to a Si-air / Si-sample interface.

[0058]

[0076] The spectrometer 704 shown in Figures 7A and 7B is a deep-etched micromachined MEMS interferometer. The MEMS interferometer includes a beam splitter 706, a fixed mirror 718, a moving mirror 720, and an actuator 722 (e.g., an electrostatic MEMS actuator) coupled to the moving mirror 720. Additionally, one or more guide structures 726 and 732 may be etched into the substrate 702 (e.g., via a DRIE process) to couple the MEMS interferometer 704 to the ATR element 706 and the microfluidic channel 708. Each guide structure 726 and 732 may be a Si-air interface.

[0059]

[0077] In the example shown in Figures 7A and 7B, the input light 714 may be coupled to the miniature ATR spectrometer 700. In some examples, the integrated spectral detection device may include a second substrate (not shown) containing one or more light redirecting elements (e.g., shaped free-space reflectors) coupled to the substrate 702, as shown in Figures 3-6. The input light 714 may be directed from the shaped free-space reflector to the MEMS interferometer 704, where the optical path difference is varied between two paths of a fixed mirror 718 and a moving mirror 720 using an actuator 722 to generate an interference beam 724. The interference beam 724 may then be directed to a channel interface 730 between the ATR element 706 and the microfluidic channel 708 via a guide structure 726. The guide structure 726 is designed to generate an angle of incidence of the interference beam 724 on the channel interface 730 that is greater than the critical angle of the Si-sample channel interface 730 to generate total internal reflection of the interference beam 724 at the channel interface 730.

[0060]

[0078] In the example shown in FIG. 7A, the interference beam 724 undergoes a single total internal reflection, and the resulting evanescent wave in the sample 712 attenuates the interference beam 724 to generate output light 728 that can be directed to a detector (not shown) via the output of the compact ATR spectrometer 700. In an example, the reflected output light 728 carrying information from the sample 712 may be collected by an output light redirecting element (e.g., molded in a second substrate coupled to the substrate 702) after refraction at the output of the compact ATR spectrometer 700. The output light redirecting element may redirect the output light 728 to a detector, as shown in FIGS. 3-6. In the example shown in FIG. 7B, multiple total internal reflections of the interference beam 724 are achieved by using an additional guide structure 732. The guide structure 732 is designed to generate an incidence angle of the interference beam 724 that exceeds the internal reflection critical angle at each reflection.

[0061]

[0079] 8 illustrates another example of a compact ATR spectrometer 800 of an integrated spectral detection device according to an embodiment. The compact ATR spectrometer 800 includes a spectrometer 804, an ATR element 806, and two opposing microfluidic channels 808a and 808b integrated in the same substrate 802. The substrate 802 may be, for example, a silicon substrate or an SOI substrate. The microfluidic channels 808a and 808b each include a sample 812 (e.g., a fluid) that flows through the microfluidic channels 808a and 808b between its respective input and output microfluidic ports 810.

[0062]

[0080] Typically, the sample 812 is measured from one side of the ATR crystal in either a macro-ATR or a micro-ATR. However, the in-plane design of the multi-substrate integrated spectral detection device shown in Figures 3-6 or the miniature ATR spectrometer shown in Figures 8 and 9 allows the sample to be inserted on both sides of the ATR element 806 by trapping the light between two microfluidic channels 808a and 808b while maintaining an angle of incidence larger than the critical angle. This design increases the number of reflections that can be achieved, thus improving the ATR sensitivity.

[0063]

[0081] The sample 812 flows adjacent to respective boundaries 830a and 830b between the corresponding microfluidic channel 808a and 808b and the ATR element 806. Each of the boundaries 830a and 830b corresponds to a respective channel interface between the ATR element 806 and the respective microfluidic channel 808a and 808b, and may be formed by a respective surface of the ATR element 806 with which the sample 812 contacts. For example, each of the channel interfaces 830a and 830b may correspond to a Si-air / Si-sample interface.

[0064]

[0082] The spectrometer 804 is a deep-etched micromachined MEMS interferometer. The MEMS interferometer includes a beam splitter 806, a fixed mirror 818, a moving mirror 820, and an actuator 822 (e.g., an electrostatic MEMS actuator) coupled to the moving mirror 820. Additionally, a guide structure 826 may be etched into the substrate 802 to couple the MEMS interferometer 804 to the ATR element 806 and the microfluidic channels 808a and 808b. The guide structure 826 may be a Si-air interface.

[0065]

[0083] In the example shown in FIG. 8, input light 814 may be coupled to a compact ATR spectrometer 800. In some examples, the integrated spectral detection device may include a second substrate (not shown) containing one or more light redirecting elements (e.g., shaped free-space reflectors) as shown in FIGS. 3-6 coupled to the substrate 802. The input light 814 may be directed from the shaped free-space reflector to a MEMS interferometer 804, where the optical path difference is varied between two paths of a fixed mirror 818 and a moving mirror 820 using an actuator 822 to generate an interference beam 824. The interference beam 824 may then be directed to the ATR element 806 and the microfluidic channels 808a and 808b via a guide structure 826. The guide structure 826 is designed to generate an angle of incidence of the interference beam 824 on the channel interface 830a that is greater than the critical angle of the Si-sample channel interface 830a to generate multiple total internal reflections of the interference beam 824 within the ATR element 806 between the channel interfaces 830a and 830b.

[0066]

[0084] Multiple total internal reflections of the interference beam 824 create evanescent waves in the sample 812 that attenuate the interference beam 824 and generate output light 828 that may be directed to a detector (not shown) via the output of the compact ATR spectrometer 800. In one example, the resulting output light 828 carrying information from the sample 812 may be collected by an output light redirecting element (e.g., molded into a second substrate coupled to the substrate 802) after refraction at the output of the compact ATR spectrometer 800. The output light redirecting element may redirect the output light 828 to a detector, as shown in Figures 3-6.

[0067]

[0085] 9 illustrates an example of an integrated spectral sensing device 900 including a compact ATR spectrometer 905, according to an embodiment. The spectral sensing device 900 includes a first substrate 902 and a second substrate 904. The first substrate 902 includes a compact ATR spectrometer 905. The second substrate 904 may include one or more light redirecting elements 906 and 908 formed therein. For example, the light redirecting elements 906 and 908 may be curved reflectors (e.g., microreflectors or micromirrors). In one example, the light redirecting elements 906 and 908 may be fabricated into a molded part of the second substrate 904 with an aluminum metal coating to improve its reflectivity.

[0068]

[0086] The integrated spectral detection device 900 may further include a package substrate 912. The first substrate 902 may be disposed on (e.g., bonded to) the package substrate 912. Furthermore, the second substrate 904 may be disposed on the first substrate 902 and bonded to the package substrate 912 at each end of the second substrate 904. The detector 910 may further be disposed on the package substrate 912. Each of the substrates 902 and 912 may be, for example, a silicon substrate or an SOI substrate. In one example, the second substrate 904 may be a plastic substrate or a glass substrate formed using an injection molding optical technique.

[0069]

[0087] The miniature ATR spectrometer 905 includes a spectrometer 916, an ATR element 918, and two opposing microfluidic channels 920a and 920b integrated on a first substrate 902. Each of the microfluidic channels 920a and 920b includes a sample 924 (e.g., a fluid) that flows through the microfluidic channel 920a and 920b between its respective input microfluidic port 926 and output microfluidic port 926. The sample 924 flows adjacent to a respective boundary 922a and 922b between the corresponding microfluidic channel 920a and 920b and the ATR element 918. Each of the boundaries 922a and 922b corresponds to a respective channel interface between the ATR element 918 and the respective microfluidic channel 920a and 920b. For example, each of the channel interfaces 922a and 922b may correspond to a Si-air / Si-sample interface.

[0070]

[0088] The spectrometer 916 is a deep-etched micromachined MEMS interferometer. The MEMS interferometer includes a beam splitter 928, a fixed mirror 930, a moving mirror 932, and an actuator 934 (e.g., an electrostatic MEMS actuator) coupled to the moving mirror 932. Additionally, a guide structure 938 may be etched into the substrate 902 to couple the MEMS interferometer 916 to the ATR element 918 and the microfluidic channels 920a and 920b. The guide structure 938 may be a Si-air interface.

[0071]

[0089] 9, the input light 936 may be coupled to the compact ATR spectrometer 905 via a light redirecting element 906. For example, the light redirecting element 906 may receive the input light 936 in an out-of-plane direction relative to the plane of the first substrate 902 and direct the input light 936 to the first substrate 902 (e.g., redirect / reflect the input light 936 90 degrees toward the first substrate 902). The input light 936 may be refracted at the input to the compact ATR spectrometer 905 and impinge on the channel interface 922b between the microfluidic channel 920b and the ATR element 918 at an angle of incidence greater than a critical angle (e.g., the critical angle of the Si-sample interface of the channel interface 922b), generating multiple total internal reflections of the input light 936 through the ATR element 918 between the microfluidic channels 920a and 920b. The input light 936 is attenuated by respective evanescent waves formed in the sample 924 contained within each of the microfluidic channels 920a and 920b. The attenuated input light is then output from the ATR element 918 as output light 940 and refracted through the guiding structure 938 towards the input of the MEMS interferometer 916.

[0072]

[0090] Within the MEMS interferometer 916, an actuator 934 is used to vary the optical path difference between the two optical paths of the fixed mirror 930 and the moving mirror 932 to generate an interference beam (interference pattern) 942 based on the output light 940. The interference beam 942 output by the MEMS interferometer 916 is redirected by the light redirecting element 908 towards the detector 910 to obtain the spectrum of the sample 924 in the microfluidic channels 920a and 920b. For example, the light redirecting element 908 may be a curved reflector configured to focus the interference beam 942 onto the active area of ​​the detector 910.

[0073]

[0091] In ATR spectroscopy, the penetration depth of light into a sample for one reflection is given by the formula (Equation 1), d p, λ, θ, n1, and n2 are the penetration depth, the radiation wavelength, the angle of incidence, the refractive index of the ATR crystal, and the refractive index of the sample. Thus, the angle of incidence and the number of reflections of the light inside the crystal may be selected based on the application and the absorption peak measured. TIFF2024516690000002.tif15170

[0074]

[0092] In some applications, it is preferable to reduce the ATR penetration depth to reduce the strong infrared absorption of water, which can block the light completely. However, in other applications, increasing the effective interaction length between the infrared light and the sample can increase the absorption of weak infrared (IR) signals above the noise level of the spectrometer. Examples of such applications include, but are not limited to, oil analysis and biological sample detection, where samples are typically dried before measuring them using IR spectroscopy. Increasing the number of reflections by increasing the length of the ATR crystal or decreasing the thickness of the ATR may improve IR absorption, but the length may be limited by limited design space and manufacturing difficulties, and the thickness may be limited by beam truncation at the input / output interface, which affects the light throughput of the device.

[0075]

[0093] The design of the in-plane ATR element shown in Figures 2-9 allows for the creation of ATR IREs with desired shapes and dimensions depending on the sample being measured. Thus, the angle of incidence and the number of reflections may be adapted to the design. Furthermore, the ATR crystal may be designed to improve the effective optical path length by increasing the number of reflections without changing the dimensions of the crystal. These designs may allow different implementations of ATR substrates or miniature ATR spectrometers that use different optical designs for the molded light redirecting elements.

[0076]

[0094] FIG. 10 is a diagram showing an example of an ATR element design according to an embodiment. The ATR element design shown in FIG. 10 is a multi-pass ATR element design that allows for a longer optical path length to be obtained within the same area. Increasing the effective optical path length can further increase the absorbance of the sample without compromising the power and signal-to-noise ratio. However, there may be bending losses (of light) that cause power loss and affect the detection limit of the spectrometer. Therefore, the ATR element design shown in FIG. 10 may be optimized to minimize bending losses while increasing absorption through a higher number of reflections.

[0077]

[0095] The ATR element design includes a substrate 1002 having an ATR element 1004 and microfluidic channels 1006a and 1006b formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In one example, the spectrometer may be formed on the same substrate 1002 as the ATR element 1004, as shown in Figures 7-9, or may be formed on a different, separate substrate, as shown in Figures 3-6.

[0078]

[0096] Each of the microfluidic channels 1006a and 1006b contains a sample (e.g., a fluid) that flows through the microfluidic channels 1006a and 1006b between its respective input microfluidic port 1010 and output microfluidic port 1010. The sample flows adjacent to a respective channel interface 1008a and 1008b between the corresponding microfluidic channel 1006a and 1006b and the ATR element 1004. For example, each of the channel interfaces 1008a and 1008b may correspond to a Si-air / Si-sample interface.

[0079]

[0097] In the example shown in Figure 10, the ATR element 1004 has a waveguide pattern formed by channel interfaces 1008a and 1008b. The waveguide pattern includes an array of parallel waveguides 1012 optically coupled at their respective ends 1014. Thus, input light 1016 incident on the channel interface 1008b of the Si sample at an angle greater than the critical angle of the channel interface 1008b is reflected via total internal reflection through the waveguide pattern of the parallel waveguides 1012 to generate output light 1018. The output light 1018 is attenuated by an evanescent wave formed in the sample based on the total internal reflection input light 1016.

[0080]

[0098] FIG. 11 illustrates another example of an ATR element design according to an embodiment. The ATR element design includes a substrate 1102 having an ATR element 1104 and microfluidic channels 1106a and 1106b formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In one example, the spectrometer may be formed on the same substrate 1102 as the ATR element 1104, as shown in FIGS. 7-9, or may be formed on a different, separate substrate, as shown in FIGS. 3-6.

[0081]

[0099] Each of the microfluidic channels 1106a and 1106b contains a sample (e.g., a fluid) that flows through the microfluidic channel 1106a and 1106b between its respective input microfluidic port 1110 and output microfluidic port 1110. The sample flows adjacent to a respective channel interface 1108a and 1108b between the corresponding microfluidic channel 1106a and 1106b and the ATR element 1104. For example, each of the channel interfaces 1108a and 1108b may correspond to a Si-air / Si-sample interface.

[0082]

[0100] The ATR element design shown in Fig. 11 is based on inputting two IR beams 1112a and 1112b into the ATR element 1104 using a V-shaped input interface 1120 and an output interface 1122, respectively. The two input beams 1112a and 1112b may originate from two IR sources or a single light source using a beam splitter and combining optics (e.g., on-chip or external optical reflector) that reflect the input beams 1112a and 1112b into the V-shaped input interface 1120. For example, the V-shaped input interface 1120 is configured to receive the first input beam 1112a and direct the first input beam 1112a to the first channel interface 1108a at an angle greater than the critical angle to generate total internal reflection of the first input beam 1112a through the ATR element 1104 between the channel interfaces 1108a and 1108b. The V-shaped interface 1120 is further configured to receive the second input beam 1112b and direct the second input beam 1112b to the second channel interface 1108b at an angle greater than the critical angle to generate total internal reflection of the first input beam 1112a through the ATR element between the channel interfaces 1108a and 1108b.

[0083]

[0101] Each input light beam 1112a and 1112b is attenuated by a respective evanescent wave formed in the sample contained in each of the microfluidic channels 1106a and 1106b. The attenuated input light beams are then output from the ATR element 1104 as output light beams 1114a and 1114b via a V-shaped output interface 1122. For example, a first output beam 1114a generated from total internal reflection of the first input beam 1112a may be output from the second channel interface 1108b via the V-shaped output interface 1122. Furthermore, a second output beam 1114b generated from total internal reflection of the second input beam 1112b may be output from the first channel interface 1108a via the V-shaped output interface 1122. The output beams 1114a and 1114b may be focused by reflectors 1116a and 1116b onto a spectrometer. For example, the V-shaped output interface 1122 may be configured to direct a first output light beam 1114a to a first reflector 1116a and a second output light beam 1114b to a second reflector 1116b to combine the first output light beam 1114a and the second output light beam 1114b and generate output light 1118 focused at the spectrometer input.

[0084]

[0102] 11, the number of internal reflections is doubled inside the ATR element 1104. In one example, the IR beam spot size may be smaller than the input interface 1120, i.e., there is no truncation at the input.

[0085]

[0103] 12A and 12B are diagrams illustrating another example of an ATR element design according to an embodiment. The ATR element design shown in FIG. 12A includes a substrate 1202 having an ATR element 1204 and microfluidic channels 1206a and 1206b formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In one example, the spectrometer may be formed on the same substrate 1202 as the ATR element 1204, as shown in FIGS. 7-9, or may be formed on a different, separate substrate, as shown in FIGS. 3-6.

[0086]

[0104] Each of the microfluidic channels 1206a and 1206b includes a sample (e.g., a fluid) that flows through the microfluidic channels 1206a and 1206b between its respective input microfluidic port 1210 and output microfluidic port 1210. The sample flows adjacent to a respective channel interface 1208a and 1208b between the corresponding microfluidic channel 1206a and 1206b and the ATR element 1204. For example, each of the channel interfaces 1208a and 1208b may correspond to a Si-air / Si-sample interface.

[0087]

[0105] The ATR element design shown in FIG. 12A is based on having two optical paths, front and back, inside the ATR element 1204, with the input and output on one side of the ATR element 1204. For example, the ATR element 1204 may include an input / output interface 1216 on its first side and a rear interface 1218 on its second side opposite the first side. The ATR element 1204 is configured to receive input light 1212 via the input / output interface 1216. The input light 1212 may strike a channel interface (e.g., channel interface 1208b) at an angle greater than the critical angle, generating total internal reflection of the input light 1212 between channel interfaces 1208a and 1208b through the ATR element 1204 towards the rear interface 1218. The rear interface 1218 may be further configured to reflect the input light via total internal reflection through the ATR element 1204 between the channel interfaces 1208a and 1208b to generate output light 1214, which may be output via the input / output interface 1216. The output light 1214 is attenuated by an evanescent wave formed in the sample based on the total internal reflection input light 1214.

[0088]

[0106] The ATR element design shown in FIG. 12A increases the number of reflections within the same ATR element length. As further shown in FIG. 12B, the two light paths (front and back) within the ATR element 1204 may be achieved using two different facet angles (θ, φ), one on either side of the ATR element. For example, the input / output interface 1216 may have a first facet angle θ, and the rear interface 1218 may have a second facet angle φ. The first facet angle θ may be configured to generate total internal reflection of the input light 1212 at a channel interface (e.g., channel interface 1208b) of the ATR element 1204 when the input light is incident perpendicularly to the input / output interface 1216. The second facet angle may be configured to generate total internal reflection of the input light 1212 at the rear interface 1218 and other channel interfaces (e.g., channel interface 1208a) of the ATR element. Additionally, the second facet angle may be configured to generate refraction of the output light 1214 at the input / output interface 1216.

[0089]

[0107] Thus, the first face angle (input / output face angle (θ)) is greater than the critical angle of the channel interface 1208b (e.g., the interface between the ATR element 1204 and the sample) such that: TIFF2024516690000003.tif7170n1 and n2 are the refractive indices of the ATR element and the sample, respectively. Additionally, the second surface angle (rear surface angle (φ)) is configured to ensure total internal reflection of light on the rear interface 1218, as follows: TIFF2024516690000004.tif7170n air is the refractive index of air.

[0090]

[0108] Additionally, the rear facet angle (φ) is further configured to ensure total internal reflection of the light at the channel interfaces 1208a and 1208b while the light reflects back through the ATR element 1204, as follows: TIFF2024516690000005.tif7170 Additionally, the rear face angle (φ) is further configured to ensure refraction of light on the input / output interface 1216 as follows: TIFF2024516690000006.tif7170 Thus, output light 1214 may be deflected from the direction of input light 1212 at an angle that depends on the rear face angle, as follows: TIFF2024516690000007.tif7170

[0091]

[0109] 13 is a diagram showing another example of an ATR element design according to an embodiment. The ATR element design shown in FIG. 13 is based on total internal reflection and interaction between light and a measurement sample at four faces of the ATR element. In this ATR element design, the ATR element is fabricated using a shape with facet angles on both side walls in addition to the input and output interfaces.

[0092]

[0110] The ATR element design includes a substrate 1302 having an ATR element 1304 and microfluidic channels 1306a and 1306b formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In one example, the spectrometer may be formed on the same substrate 1302 as the ATR element 1304, as shown in Figures 7-9, or may be formed on a different, separate substrate, as shown in Figures 3-6.

[0093]

[0111] Each of the microfluidic channels 1306a and 1306b includes a sample (e.g., a fluid) that flows through the microfluidic channels 1306a and 1306b between its respective input microfluidic port 1310 and output microfluidic port 1310. The sample flows adjacent to a respective channel interface 1308a and 1308b between the corresponding microfluidic channel 1306a and 1306b and the ATR element 1304. For example, each of the channel interfaces 1308a and 1308b may correspond to a Si-air / Si-sample interface. In the example shown in FIG. 13, the channel interfaces 1308a and 1308b are sloped sidewalls of the substrate 1302. For example, an additional etching step, such as an anisotropic KOH etch, may be added to the DRIE process used in the manufacturing procedure of the MEMS spectrometer to create the sloped sidewalls.

[0094]

[0112] The angled sidewalls forming the channel interfaces 1308a and 1308b generate a light path 1315 having a three-dimensional spiral shape within the ATR element 1304, instead of multiple reflections in a conventional single 2D plane. For example, the ATR element 1304 may be configured to receive input light 1312 at an angle of incidence greater than a critical angle of one of the angled sidewalls (e.g., channel interface 1308b) and to reflect the input light 1312 in a spiral shape via total internal reflection through the ATR element 1304 such that the input light 1312 is reflected off the angled sidewalls (e.g., channel interfaces 1308a and 1308b) and both the top and bottom surfaces of the ATR element 1304 to generate output light 1314 that is attenuated by evanescent waves formed within the sample.

[0095]

[0113] In one example, to take advantage of additional reflections, an additional microfluidic channel 1318 containing sample may be inserted above the substrate 1302 (e.g., on the top surface 1316 of the substrate 1302). For example, a microfluidic PDMS device 1320 may be bonded onto the top surface 1316 of the substrate 1302. In this ATR element design, the input light 1312 not only propagates parallel to the substrate 1302, but also reflects back from the top silicon interface with the PDMS device 1320.

[0096]

[0114] FIG. 14 illustrates another example of an ATR element design according to an embodiment. The ATR element design illustrated in FIG. 14 provides a variable number of internal reflections to support various target applications. The ATR element design includes a substrate 1402 having an ATR element 1404 and multiple sets of opposing microfluidic channels (e.g., a first set of opposing microfluidic channels 1406a and 1406b, a second set of opposing microfluidic channels 1406c and 1406d, and a third set of opposing microfluidic channels 1406e and 1406f) formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In an example, the spectrometer may be formed on the same substrate 1402 as the ATR element 1404, as shown in FIGS. 7-9, or may be formed on a different, separate substrate, as shown in FIGS. 3-6.

[0097]

[0115] One or more of the sets of microfluidic channels 1406a / 1406b, 1406c / 1406d, and / or 1406e / 1406f may include a sample (e.g., a fluid) flowing through the microfluidic channel between its respective input microfluidic port 1410 and output microfluidic port 1410. The sample flows adjacent to a respective channel interface 1408a / 1408b, 1408c / 1408d, and / or 1408e / 1408f between the corresponding microfluidic channel 1406a / 1406b, 1406c / 1406d, and / or 1406e / 1406f and the ATR element 1404. For example, each of the channel interfaces 1408a-1408f may correspond to a Si-air / Si-sample interface.

[0098]

[0116] Since the optimal ATR effective penetration depth depends directly on the target application and the IR absorption level of the measurement sample, the ATR element 1404 may be configured as a stepped waveguide with different widths 1416a, 1416b and 1416c between opposing microfluidic channels in each of the sets of opposing microfluidic channels 1406a / 1406b, 1406c / 1406d and 1406e / 1406f, respectively. The number of reflections is a function of the widths 1416a, 1416b and 1416c, as follows: TIFF2024516690000008.tif9170N is the number of internal reflections, θ is the angle of incidence, and L and W are the length and width of the ATR element. A wide ATR element may be used for strongly absorbing materials and a narrow ATR element may be used for weakly absorbing materials.

[0099]

[0117] Therefore, the stepped waveguide design of the ATR element shown in FIG. 14 may be used to measure different types of samples. For example, a strongly absorbing sample may be inserted into the microfluidic channels 1406a and 1406b with a larger ATR width 1416a therebetween. Input light 1412 incident on the channel interface 1408b at an angle greater than the critical angle of the Si-sample channel interface 1408b is reflected via total internal reflection through the ATR element 1404 between the channel interfaces 1408a and 1408b and between the Si-air channel interfaces 1408c / 1408d and 1408e / 1408f to generate output light 1414. The output light 1414 is attenuated by evanescent waves formed in the sample in the microfluidic channels 1406a and 1406b based on the total internal reflection input light 1412. Samples with weaker absorption characteristics may be similarly measured using the second set of microfluidic channels 1406c / 1406d or the third set of microfluidic channels 1406e / 1406f.

[0100]

[0118] FIG. 15 illustrates another example of an ATR element design according to an embodiment. The ATR element design illustrated in FIG. 15 also provides a variable number of internal reflections to support various target applications. The ATR element design includes a substrate 1502 having an ATR element 1504 and a set of multiple opposing microfluidic channels (e.g., a first set of opposing microfluidic channels 1506a and 1506b and a second set of opposing microfluidic channels 1506c and 1506d) formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In an example, the spectrometer may be formed on the same substrate 1502 as the ATR element 1404, as shown in FIGS. 7-9, or may be formed on a different, separate substrate, as shown in FIGS. 3-6.

[0101]

[0119] One or more of the sets of microfluidic channels 1506a / 1506b and / or 1506c / 1506d may include a sample (e.g., a fluid) flowing through the microfluidic channel between its respective input microfluidic port 1510 and output microfluidic port 1510. The sample flows adjacent a respective channel interface 1508a / 1508b and / or 1508c / 1508d between the corresponding microfluidic channel 1506a / 1506b and / or 1506c / 1506d and the ATR element 1504. For example, each of the channel interfaces 1508a-1508d may correspond to a Si-air / Si-sample interface.

[0102]

[0120] The ATR element 1504 shown in FIG. 15 is configured as a tapered waveguide with an ATR width 1516 that varies linearly between the microfluidic channels 1506a / 1506b and the microfluidic channels 1506c / 1506d. In this example, the angle of incidence may vary through the ATR element 1504 due to the taper: however, the ATR element design can keep the angle of incidence above the critical angle of the Si-air (or Si-sample) interface. As in the example shown in FIG. 14, a wide ATR width may be used for strongly absorbing samples, while a narrow width may be used for weakly absorbing samples. For example, a weakly absorbing sample may be inserted into the second set of microfluidic channels 1506c and 1506d. Input light 1512 incident on channel interface 1508b at an angle greater than the critical angle of the Si-air channel interface 1508b is reflected by total internal reflection through the ATR element 1504 between Si-air channel interfaces 1508a and 1508b and between Si-sample channel interfaces 1508c and 1508d to generate output light 1514. The output light 1514 is attenuated by evanescent waves that form in the sample in microfluidic channels 1506c and 1506d based on the totally internally reflected input light 1512.

[0103]

[0121] FIG. 16 illustrates another example of an ATR element design according to an embodiment. The ATR element design illustrated in FIG. 16 also provides a variable number of internal reflections to support various target applications. The ATR element design includes a substrate 1602 having an ATR element including a plurality of waveguides 1604a, 1604b, and 1604c and a plurality of opposing sets of microfluidic channels (e.g., a first set of opposing microfluidic channels 1606a and 1606b, a second set of opposing microfluidic channels 1606c and 1606d, and a third set of opposing microfluidic channels 1606e and 1606f) formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In an example, the spectrometer may be formed on the same substrate 1602 as the ATR element 1604, as shown in FIGS. 7-9, or may be formed on a different, separate substrate, as shown in FIGS. 3-6.

[0104]

[0122] One or more of the sets of microfluidic channels 1606a / 1606b, 1606c / 1606d, and / or 1606e / 1606f may include a sample (e.g., a fluid) flowing through the microfluidic channel between its respective input microfluidic port 1610 and output microfluidic port 1610. The sample flows adjacent to a respective channel interface 1608a / 1608b, 1608c / 1608d, and / or 1608e / 1608f between a corresponding microfluidic channel 1606a / 1606b, 1606c / 1606d, and / or 1606e / 1606f and a corresponding waveguide 1604a, 1604b, and / or 1604c. For example, each of the channel interfaces 1608a-1608f may correspond to a Si-air / Si-sample interface.

[0105]

[0123] Each of the ATR waveguides 1604a, 1604b, and 1604c may have different respective widths 1620a, 1620b, and 1620c configured to generate different numbers of internal reflections. Additionally, the ATR element design may further include movable mirrors 1616 and 1618 formed in the substrate 1602 (e.g., via a DRIE process with a metallization step). Each movable mirror (e.g., the input mirror 1616 and the output mirror 1618) may be coupled, for example, to a respective actuator (e.g., a MEMS actuator, such as an electrostatic comb actuator). In the example shown in FIG. 16, two different actuators may be used because the 90 degree optical deflection in the trapezoidal ATR element design causes the input mirror 1616 and the output mirror 1618 to translate in two perpendicular directions. If a parallelogram-shaped ATR element design is used, in which the optical path can be translated without deflection, a single actuator may be used for both mirrors 1616 and 1618.

[0106]

[0124] Depending on the positions of the movable mirrors 1616 and 1618, the input light 1612 may be reflected by the input mirror 1616 towards a selected one of the ATR waveguides 1604a, 1604b or 1604c with a desired number of reflections for a particular application (sample). The output light 1614 generated based on the number of total internal reflections in the selected waveguide 1604a, 1604b or 1604c may then be received by the output mirror 1618 and reflected towards an output interface.

[0107]

[0125] ATR analysis of micron-sized particles in liquids, such as microplastics in water, is typically challenged by random distribution of particles throughout the liquid, which may be outside of the vicinity of the ATR effective penetration depth with strong IR absorption in water. In various embodiments of the present disclosure, accumulation of particles on the sidewalls of the ATR element may be performed by separation and sorting of particles in a microfluidic channel to enter the evanescent field region of the outer guided mode of the ATR crystal.

[0108]

[0126] In some examples, field-flow fractionation (FFF) may be used for particle separation. In FFF, an external actuation field is applied to force particles to move towards the sidewall in the direction of the applied field. In general, the applied field may be electrical, thermal, gravitational or cross-flow induced. Various other active separation mechanisms may be used in ATR designs. For example, dielectrophoresis (DEP) may be used to electrically control the movement of particles suspended in a fluid. In DEP, suspended dielectric particles are exposed to a non-uniform electric field to polarize the particles, thereby moving them towards or away from regions of high electric field strength. The strength and direction of the DEP force depend on the electrical properties of the medium and the particles, the shape and size of the particles, and the frequency and phase of the applied electric field.

[0109]

[0127] FIG. 17 illustrates another example of an FFF-based ATR element design, according to an embodiment. The ATR element design includes a substrate 1702 having an ATR element 1704 (e.g., a waveguide) and microfluidic channels 1706a and 1706b formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In one example, the spectrometer may be formed on the same substrate 1702 as the ATR element 1704, as shown in FIGS. 7-9, or may be formed on a different, separate substrate, as shown in FIGS. 3-6.

[0110]

[0128] Each of the microfluidic channels 1706a and 1706b contains a sample (e.g., a fluid) that flows through the microfluidic channel 1706a and 1706b between its respective input microfluidic port 1710 and output microfluidic port 1710. The sample flows adjacent a respective channel interface 1708a and 1708b between the corresponding microfluidic channel 1706a and 1706b and the ATR element 1704. For example, each of the channel interfaces 1708a and 1708b may correspond to a vertical sidewall of the ATR element 1704 that forms a Si-air / Si-sample interface.

[0111]

[0129] 17, an actuation field generator 1716 formed from electrodes may be further disposed on the top surface of the substrate 1702 adjacent to the microfluidic channels 1706a and 1706b to electrically induce an external actuation field 1718. The applied actuation field 1718 is configured to move particulates 1720 in the sample to the sidewalls (e.g., channel interfaces 1708a and 1708b) of the ATR element 1704. The particulates 1720 accumulated on the sidewalls interact with an evanescent wave generated based on total internal reflection of the input light 1712 through the ATR element 1704 to generate output light 1714 attenuated by the evanescent wave.

[0112]

[0130] FIG. 18 illustrates another example of a DEP-based ATR element design, according to an embodiment. The ATR element design includes a substrate 1802 having an ATR element 1804 (e.g., a waveguide) and microfluidic channels 1806a and 1806b formed therein (e.g., via a DRIE process). The substrate may be, for example, a silicon substrate or an SOI substrate. In one example, the spectrometer may be formed on the same substrate 1802 as the ATR element 1804, as shown in FIGS. 7-9, or may be located on a different, separate substrate, as shown in FIGS. 3-6.

[0113]

[0131] Each of the microfluidic channels 1806a and 1806b contains a sample (e.g., a fluid) that flows through the microfluidic channels 1806a and 1806b between its respective input microfluidic port 1810 and output microfluidic port 1810. The sample flows adjacent to a respective channel interface 1808a and 1808b between the corresponding microfluidic channel 1806a and 1806b and the ATR element 1804. For example, each of the channel interfaces 1808a and 1808b may correspond to a vertical sidewall of the ATR element 1804 that forms a Si-air / Si-sample interface.

[0114]

[0132] In the DEP ATR element design shown in FIG. 18, an actuation field generator 1816 formed from an interdigitated electrode system may further be on the substrate 1802 to electrically induce a non-uniform electric field. The interdigitated electrode system 1816 generates a large value electric field gradient using a moderate value of applied voltage. In the example shown in FIG. 18, the interdigitated electrode 1816 may be applied to the backside of a glass substrate 1818 using, for example, lithography techniques. The glass substrate 1818 may then be bonded to the top of the silicon substrate 1802 containing the ATR element 1804. The AC-voltaged electrode 1816 provides a DEP force to trap the microparticles below the center of the electrode 1816. The electrode 1816 may be positioned relative to the microfluidic channels 1806a and 1806b such that the microparticles in the sample are aggregated toward the adjacent sidewalls (e.g., channel interfaces 1808a and 1808b) of the optical interaction region.

[0115]

[0133] Thus, the applied actuation field is configured to move particles in the sample to the side walls (e.g., channel interfaces 1808a and 1808b) of the ATR element 1804. The particles accumulated on the side walls interact with the evanescent wave generated based on total internal reflection of the input light 1812 through the ATR element 1804, generating output light 1814 that is attenuated by the evanescent wave.

[0116]

[0134] The following provides an overview of examples of the present disclosure.

[0117]

[0135] Example 1: An integrated spectral detection device comprising: a first substrate comprising an attenuated total internal reflection (ATR) element, a microfluidic channel, and a channel interface corresponding to a boundary between the ATR element and the microfluidic channel formed therein, the ATR element configured to receive input light and generate output light based on total internal reflection of the input light at the channel interface, the output light being attenuated by an evanescent wave generated by a sample contained within the microfluidic channel based on the total internal reflection of the input light; a spectrometer configured to generate an interference beam, the interference beam corresponding to the input light or generated based on the output light; and a detector configured to detect a spectrum of the interference beam or the output light.

[0118]

[0136] Example 2: The integrated detection device of Example 1, wherein the microfluidic channel comprises a first microfluidic channel having a first channel interface with the ATR element and a second microfluidic channel having a second channel interface with the ATR element, and the total internal reflection of the input light occurs between the first channel interface and the second channel interface.

[0119]

[0137] Example 3: The integrated detection device of Example 2, wherein the first substrate comprises a silicon substrate, and the first channel interface and the second channel interface each comprise a silicon-air interface.

[0120]

[0138] Example 4: An integrated detection device as described in Example 2 or 3, wherein the ATR element has inclined sidewalls that form the first channel interface and the second channel interface, the inclined sidewalls generating an optical path of the input light having a three-dimensional spiral shape, and further comprising an additional microfluidic channel disposed on the top surface of the first substrate above the ATR element within the optical path of the input light.

[0121]

[0139] Example 5: An integrated detection device as described in Example 2 or 3, wherein the ATR element comprises a waveguide pattern formed by the first channel interface and the second channel interface, the waveguide pattern comprising an array of parallel waveguides optically coupled at their respective ends.

[0122]

[0140] Example 6: The integrated detection device of Example 2 or 3, wherein the input light comprises a first input beam and a second input beam, the output light comprises a first output beam generated from the total internal reflection of the first input beam and a second output beam generated from the total internal reflection of the second input beam, the ATR element comprises a V-shaped input interface configured to receive the first input beam and direct the first input beam to the first channel interface and to receive a second input beam and direct the second input beam to the second channel interface, the ATR element comprises a V-shaped output interface configured to direct the first output beam to a first reflector and direct the second output beam to a second reflector, the first reflector and second reflector are configured to combine the first output beam and the second output beam to generate the output light.

[0123]

[0141] Example 7: The integrated detection device of Example 2 or 3, wherein the ATR element comprises an input / output interface on a first side thereof and a rear interface on a second side thereof opposite the first side, and the ATR element is configured to receive the input light via the input / output interface, totally internally reflect the input light from the rear interface, and output the output light via the input / output interface.

[0124]

[0142] Example 8: The integrated detection device of Example 7, wherein the input / output interface has a first surface angle and the rear interface has a second surface angle, the first surface angle configured to generate the total internal reflection of the input light at the first channel interface, the input light is incident perpendicularly to the input / output interface, the second surface angle configured to generate the total internal reflection of the input light at the rear interface and the second channel interface, and the second surface angle further configured to generate refraction of the output light at the input / output interface.

[0125]

[0143] Example 9: An integrated detection device described in any one of Examples 1 to 8, further comprising: a second substrate parallel to the first substrate, the second substrate comprising the spectrometer; a first light redirecting element configured to receive the output light from the ATR element and direct the output light to the spectrometer; and a second light redirecting element configured to reflect the interference beam to the detector.

[0126]

[0144] Example 10: An integrated detection device as described in Example 9, wherein the ATR element has an inclined surface configured to couple the output light into the first light redirecting element in an out-of-plane direction relative to a plane of the ATR element.

[0127]

[0145] Example 11: The integrated detection device of Example 9, further comprising a third light redirecting element configured to receive the output light at a first plane of the ATR element and reflect the output light in an out-of-plane direction relative to the first plane toward the first light redirecting element, the first light redirecting element configured to redirect the output light from the out-of-plane direction to an in-plane direction relative to a second plane of the second substrate, the first plane and the second plane being parallel.

[0128]

[0146] Example 12: An integrated detection device described in any one of Examples 1 to 8, further comprising: a second substrate having the spectrometer; a third substrate having a surface, the first substrate, the second substrate and the detector being disposed on the surface of the third substrate; and a light redirecting element disposed on the surface of the third substrate, the light redirecting element configured to receive the input light in an out-of-plane direction relative to the plane of the first substrate and the second substrate, and to direct the input light toward the first substrate.

[0129]

[0147] Example 13: An integrated detection device described in any one of Examples 1 to 8, wherein the first substrate further comprises a spectrometer, the spectrometer comprising a microelectromechanical system (MEMS) interferometer etched into the first substrate.

[0130]

[0148] Example 14: An integrated detection device as described in Example 13, wherein the MEMS interferometer is configured to receive the input beam, generate the interference beam from the input beam corresponding to the input light, and direct the interference beam to the ATR element.

[0131]

[0149] Example 15: The integrated detection device of Example 14, further comprising a first guide structure etched into the substrate configured to reflect the input light toward the channel interface at an angle of incidence equal to or greater than a critical angle of the channel interface to generate total internal reflection of the input light at the channel interface.

[0132]

[0150] Example 16: An integrated detection device as described in Example 15, wherein the ATR element further comprises a second guide structure etched into the substrate and configured to promote multiple total internal reflections of the input light between the channel interface and the second light redirection element.

[0133]

[0151] Example 17: The integrated detection device of Example 16, wherein the first substrate comprises a silicon substrate, and the first guide structure and the second guide structure each comprise a respective silicon-air interface.

[0134]

[0152] Example 18: An integrated detection device described in any one of Examples 13 to 17, wherein the MEMS interferometer is configured to receive the output light from the ATR element and generate the interference beam based on the output light.

[0135]

[0153] Example 19: An integrated spectral detection device described in any one of Examples 1 to 18, wherein the microfluidic channels comprise a plurality of sets of two opposing microfluidic channels, each of the plurality of sets of two opposing microfluidic channels configured to generate different numbers of reflections of the input light.

[0136]

[0154] Example 20: The integrated spectral detection device of Example 19, wherein the ATR element further comprises a stepped waveguide having different widths between two opposing microfluidic channels in each of a plurality of sets of two opposing microfluidic channels.

[0137]

[0155] Example 21: The integrated spectral detection device of Example 19, wherein the ATR element further comprises a tapered waveguide between two opposing sets of the microfluidic channels.

[0138]

[0156] Example 22: The integrated spectral detection device of Example 19, wherein the ATR element comprises a plurality of waveguides for a plurality of sets of two opposing microfluidic channels, each of the plurality of waveguides being between two opposing microfluidic channels of a respective one of the plurality of sets of two opposing microfluidic channels, each of the plurality of waveguides having a different width, and further comprising a first movable mirror configured to reflect the input light to a selected waveguide of the plurality of waveguides, and a second movable mirror configured to receive the output light from the selected waveguide.

[0139]

[0157] Example 23: An integrated spectral detection device described in any one of Examples 1 to 22, wherein the ATR element has a sidewall forming the channel interface and further comprises an actuation field generator configured to apply an actuation field to the sample in the microfluidic channel, the actuation field being configured to move particles in the sample to the sidewall of the ATR element to interact with the evanescent wave.

[0140]

[0158] Example 24: An integrated spectral detection device as described in Example 23, wherein the actuation field comprises an electric field and the actuation field generator comprises an electrode on an upper surface of the first substrate configured to generate the electric field.

[0141]

[0159] Example 25: An integrated spectral detection device as described in Example 23, wherein the actuating field comprises a non-uniform electric field configured to apply a dielectrophoretic force to the microparticles, and the actuating field generator comprises a comb-shaped electrode on an upper surface of the first substrate.

[0142]

[0160] Within this disclosure, the word "exemplary" is used to mean "serving as an example, embodiment, or illustration." Any implementation or aspect described herein as "exemplary" should not necessarily be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term "aspect" does not require that all aspects of the disclosure include the discussed feature, advantage, or mode of operation. The term "coupled" is used herein to refer to a direct or indirect coupling between two objects. For example, if object A physically contacts object B, and object B contacts object C, objects A and C may still be considered to be coupled to each other even if they are not in direct physical contact with each other. For example, a first object may be coupled to a second object even if the first object is not in direct physical contact with the second object. The terms "circuit" and "circuitry" are used broadly and are intended to include both hardware implementations of electrical devices and conductors and software implementations of information and instructions, which when connected and configured enable the performance of the functions described in this disclosure without being limited to types of electronic circuits, and which software implementations, when executed by a processor, enable the performance of the functions described in this disclosure.

[0143]

[0161] One or more of the components, steps, features and / or functions shown in Figures 1-18 may be rearranged and / or combined into a single component, step, feature or function, or may be embodied in several components, steps or functions. Additional elements, components, steps and / or functions may be added without departing from the novel features disclosed herein. The apparatus, devices and / or components shown in Figures 1-18 may be configured to perform one or more of the methods, features or steps described herein. The novel algorithms described herein may be efficiently implemented in software and / or embedded in hardware.

[0144]

[0162] It is understood that the specific order or hierarchy of steps in the methods disclosed is illustrative of example processes. Based on design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy presented, unless specifically stated herein.

[0145]

[0163] The foregoing description is provided to enable those skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects set forth herein, but are to be accorded the full scope consistent with the language of the claims, and reference to an element in the singular is not intended to mean "the only one" unless specifically so stated, but rather "one or more." Unless specifically stated otherwise, the term "several" refers to one or more. A phrase referring to "at least one of" a list of items refers to any combination of those items, including a single member. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, and: a and b, and: a and c, and: b and c, and: a, b, and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later become known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be made available to the public, regardless of whether such disclosure is expressly recited in the claims.

Claims

1. 1. An integrated spectral sensing device, comprising: a first substrate comprising an attenuated total internal reflection (ATR) element, a microfluidic channel, and a channel interface corresponding to a boundary between the ATR element and the microfluidic channel formed therein, the channel interface being formed on a sidewall of the ATR element, the ATR element being configured to receive input light and generate output light based on total internal reflection of the input light at the channel interface, the output light being attenuated by an evanescent wave generated by a sample contained within the microfluidic channel based on the total internal reflection of the input light; a spectrometer configured to generate an interference beam, the interference beam corresponding to the input light or generated based on the output light; a detector configured to detect the spectrum of the interference beam or the output light.

2. 2. The integrated spectral detection device of claim 1, wherein the microfluidic channel comprises a first microfluidic channel having a first channel interface with the ATR element and a second microfluidic channel having a second channel interface with the ATR element, and the total internal reflection of the input light occurs between the first channel interface and the second channel interface.

3. The integrated spectral sensing device of claim 2 , wherein the first substrate comprises a silicon substrate, and the first channel interface and the second channel interface each comprise a silicon-air interface.

4. the ATR element includes slanted sidewalls that define the first and second channel interfaces, the slanted sidewalls generating an optical path for the input light having a three-dimensional helical shape; and The integrated spectral sensing device of claim 2 , further comprising an additional microfluidic channel disposed on the top surface of the first substrate above the ATR element in the optical path of the input light.

5. 3. The integrated spectral sensing device of claim 2, wherein the ATR element comprises a waveguide pattern formed by the first channel interface and the second channel interface, the waveguide pattern comprising an array of parallel waveguides optically coupled at their respective ends.

6. the input light comprises a first input beam and a second input beam; the output light comprises a first output beam generated from the total internal reflection of the first input beam and a second output beam generated from the total internal reflection of the second input beam; the ATR element comprises a V-shaped input interface configured to receive the first input beam and direct the first input beam to the first channel interface and to receive the second input beam and direct the second input beam to the second channel interface; the ATR element includes a V-shaped output interface configured to direct the first output beam toward a first reflector and to direct the second output beam toward a second reflector; The integrated spectral sensing device of claim 2 , wherein the first reflector and the second reflector are configured to combine the first output beam and the second output beam to generate the output light.

7. the ATR element has an input / output interface on a first side thereof and a rear interface on a second side thereof opposite the first side; 3. The integrated spectral sensing device of claim 2, wherein the ATR element is configured to receive the input light through the input / output interface, totally internally reflect the input light from the rear interface, and output the output light through the input / output interface.

8. the input / output interface has a first surface angle and the rear interface has a second surface angle; the first face angle is configured to generate the total internal reflection of the input light at the first channel interface, the input light being incident normal to the input / output interface; 8. The integrated spectral sensing device of claim 7, wherein the second face angle is configured to generate the total internal reflection of the input light at the rear interface and the second channel interface, and the second face angle is further configured to generate refraction of the output light at the input / output interface.

9. a second substrate parallel to the first substrate, the second substrate comprising the spectrometer; a first light redirecting element configured to receive the output light from the ATR element and direct the output light to the spectrometer; The integrated spectral sensing device of claim 1 , further comprising: a second light redirecting element configured to reflect the interfering beam to the detector.

10. 10. The integrated spectral sensing device of claim 9, wherein the ATR element comprises an angled surface configured to couple the output light to the first light-redirecting element in an out-of-plane direction relative to a plane of the ATR element.

11. 10. The integrated spectral sensing device of claim 9, further comprising a third light redirecting element configured to receive the output light at a first plane of the ATR element and reflect the output light in an out-of-plane direction relative to the first plane toward the first light redirecting element, the first light redirecting element configured to redirect the output light from the out-of-plane direction to an in-plane direction relative to a second plane of the second substrate, the first plane and the second plane being parallel.

12. a second substrate comprising the spectrometer; a third substrate having a surface, the first substrate, the second substrate and the detector being disposed on the surface of the third substrate; 2. The integrated spectral sensing device of claim 1, further comprising: a light redirecting element disposed on the surface of the third substrate, the light redirecting element configured to receive the input light in an out-of-plane direction relative to the plane of the first substrate and the second substrate and to direct the input light toward the first substrate.

13. The integrated spectral sensing device of claim 1 , wherein the first substrate further comprises the spectrometer, the spectrometer comprising a micro-electro-mechanical system (MEMS) interferometer etched into the first substrate.

14. 14. The integrated spectral sensing device of claim 13, wherein the MEMS interferometer is configured to receive the input beam, generate the interference beam from the input beam corresponding to the input light, and direct the interference beam to the ATR element.

15. 15. The integrated spectral sensing device of claim 14, further comprising a first guiding structure etched into the substrate configured to reflect the input light toward the channel interface at an angle of incidence that is greater than or equal to a critical angle of the channel interface to generate the total internal reflection of the input light at the channel interface.

16. The ATR element is 16. The integrated spectral sensing device of claim 15, further comprising a second guiding structure etched into the substrate and configured to promote multiple total internal reflections of the input light between the channel interface and the second light redirecting element.

17. 17. The integrated spectral sensing device of claim 16, wherein the first substrate comprises a silicon substrate, and the first guiding structure and the second guiding structure each comprise a respective silicon-air interface.

18. The integrated spectral sensing device of claim 13 , wherein the MEMS interferometer is configured to receive the output light from the ATR element and generate the interference beam based on the output light.

19. 2. The integrated spectral detection device of claim 1 , wherein the microfluidic channels comprise a plurality of sets of two opposing microfluidic channels, each of the plurality of sets of two opposing microfluidic channels configured to generate a respective different number of reflections of the input light.

20. 20. The integrated spectral detection device of claim 19, wherein the ATR element further comprises a stepped waveguide having a different width between two opposing microfluidic channels of each of a plurality of sets of two opposing microfluidic channels.

21. 20. The integrated spectral detection device of claim 19, wherein the ATR element further comprises a tapered waveguide between two opposing sets of the microfluidic channels.

22. The ATR element comprises a plurality of waveguides for the plurality of sets of two opposing microfluidic channels, each of the plurality of waveguides being between two opposing microfluidic channels of a respective one of the plurality of sets of two opposing microfluidic channels, each of the plurality of waveguides having a different width, and 20. The integrated spectral sensing device of claim 19, further comprising: a first movable mirror configured to reflect the input light into a selected one of the plurality of waveguides; and a second movable mirror configured to receive the output light from the selected one of the waveguides.

23. 2. The integrated spectral detection device of claim 1, wherein the ATR element further comprises an actuation field generator configured to apply an actuation field to the sample in the microfluidic channel, the actuation field configured to move particles in the sample to the sidewall of the ATR element to interact with the evanescent wave.

24. 24. The integrated spectral sensing device of claim 23, wherein the actuation field comprises an electric field, and the actuation field generator comprises an electrode on a top surface of the first substrate configured to generate the electric field.

25. 24. The integrated spectral sensing device of claim 23, wherein the actuating field comprises a non-uniform electric field configured to apply a dielectrophoretic force to the microparticles, and the actuating field generator comprises an interdigitated electrode on a top surface of the first substrate.

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