Patent Description:
A fluid cell may be filled with a fluid, such as a liquid, gas, or plasma. The fluid inside the gas cell may be detected by sending light through the fluid cell. A portion of the light is absorbed by the fluid, while the rest may be detected, for example, by a spectrometer. Miniaturization of fluid analyzers may be achieved using a micro-electro-mechanical-systems (MEMS) spectrometer, such as a Fourier Transform Infrared (FTIR) spectrometer. In addition, miniaturization of fluid analyzers may allow for integration of fluid analyzers with sensors and other components and enable mass production of integrated devices for fluid analysis. <CIT> discloses a flow cell device that enables removably connecting an optical analysis device to an attachment point of the flow cell device allowing for interrogation of fluids in an analysis zone. The flow cell device comprises a ball lens that is part of the wall of a flow cell.

The present invention is directed to an optical fluid analyzer as defined by the appended claims. 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 and is intended neither to identify key or critical elements of all aspects of the disclosure nor 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 in a form as a prelude to the more detailed description that is presented later.

Various aspects of the disclosure relate to an optical fluid analyzer including a fluid cell configured to receive a sample (e.g., a fluid, such as a liquid, gas, or plasma) under test. Input light is sent through the fluid cell, where a portion of the light is absorbed by the fluid and the remaining portion of the light can be detected by a spectrometer. In some examples, the spectrometer may be implemented as a micro-electro-mechanical-systems (MEMS) spectrometer. Optical elements are used to seal the fluid cell on opposing sides thereof and to allow the light to enter and exit the fluid cell. In addition, the optical elements allow the light spectrum to be transmitted therethrough with a negligible absorption value.

The optical fluid analyzer further includes a machine learning (ML) engine, such as an artificial intelligence (AI) engine, that is configured to generate a result defining at least one parameter of the fluid based on a spectrum produced by the spectrometer. For example, the AI engine may be configured to predict the measured fluid and its concentration. Other parameters, such as the energy content in the fluid, the total volatile organic compound, the amount of particulate matter in the fluid, and other suitable parameters may be estimated by the AI engine. In some examples, the AI engine may use correction and prediction models, such as chemometrics, Kalman filtering, etc., to predict or estimate the parameter(s).

In some examples, the optical fluid analyzer may be implemented as a spectroscopic lab-in-a-box for biological sample detection, such as for virus infection detection. The optical fluid analyzer may be suitable, for example, for mass screening in pandemic situations enabling ultra-rapid and low-cost analysis for non-specialized users. The optical fluid analyzer can further be scalable and be produced with large quantities. The fluid cell in the optical fluid analyzer is designed and implemented such that the fluid sealing is maintained for infection control purpose.

In an example, an optical fluid analyzer is disclosed. The optical fluid analyzer includes a light source configured to generate input light, a fluid cell configured to receive a fluid, a first optical window configured to seal the fluid cell on a first side thereof and a second optical element configured to seal the fluid cell on a second side thereof. The first optical element is further configured to direct the input light into the fluid cell on the first side thereof, and the second optical element is further configured to receive output light from the fluid cell via the second side thereof. The optical fluid analyzer further includes a spectrometer configured to receive the output light via the second optical element and to obtain a spectrum of the fluid based on the output light, and a machine learning engine configured to receive the spectrum and to generate a result defining at least one parameter of the fluid.

<FIG> is a diagram illustrating an optical fluid analyzer <NUM> according to some aspects. In some examples, the optical fluid analyzer <NUM> may be a portable, handheld device. The optical fluid analyzer <NUM> includes a fluid cell <NUM>. A fluid <NUM> (e.g., a gas, liquid, or plasma) may enter the fluid cell <NUM> via one or more fluid inlets <NUM>. In addition, the fluid <NUM> may exit the fluid cell <NUM> via one or more fluid outlets <NUM>. The fluid <NUM> inside the fluid cell <NUM> may be detected by directing input light <NUM> from a light source <NUM> into the fluid cell <NUM> via a first optical element <NUM>. The first optical element <NUM> is configured to seal the fluid cell <NUM> on a first side 115a thereof and to direct the input light <NUM> into the fluid cell <NUM> on the first side 115a thereof.

A portion of the input light <NUM> may be absorbed by the fluid, while the remainder of the light may be output from the fluid cell <NUM> as output light <NUM> via a second optical element <NUM>. The second optical element <NUM> is configured to seal the fluid cell <NUM> on a second side 115b thereof and to direct the output light <NUM> from the fluid cell <NUM> to a spectrometer <NUM>. In some examples, the second optical element <NUM> may be a flat optical window such as a sapphire window According to the invention the first optical element comprises a ball lens coated with a filter response coating on opposite ends thereof. In other examples, the second optical element <NUM> may include one or more optical coupling elements, such as ball lenses, half-ball lenses, or Plano convex lenses. In some examples, the optical fluid analyzer <NUM> may include optical coupling elements in addition to the optical elements <NUM> and <NUM>. For example, the optical fluid analyzer <NUM> may include one or more reflectors (e.g., mirrors), lenses, or other suitable optical coupling elements.

In some examples, the fluid cell <NUM> has an optimum cell length that balances light absorption by the fluid <NUM> and saturation of the absorption signal. For example, increasing the fluid cell length may increase light absorption by the fluid <NUM>. As light absorption increases, low fluid concentrations are easier to detect. However, if the fluid cell length is too long, the absorption signal may saturate for fluids <NUM> having relatively high concentrations.

The spectrometer <NUM> may be, for example, a Fourier Transform infrared (FTIR) spectrometer configured to produce an interferogram that may be detected by a detector (e.g., an InGaAs photo detector) of the spectrometer <NUM>. The output of the detector may then be processed by the spectrometer <NUM> to obtain a spectrum <NUM> of the detected light. In some examples, the spectrometer <NUM> may include a Michelson interferometer or a Fabry-Perot interferometer.

In some examples, the spectrometer <NUM> may be implemented, for example, as a micro-electro-mechanical-systems (MEMS) spectrometer, such as a MEMS FTIR spectrometer. As used herein, the term MEMS refers to the integration of mechanical elements, sensors, actuators and electronics on a common substrate through microfabrication technology. For example, the microelectronics are typically fabricated using an integrated circuit (IC) process, while the micromechanical components are fabricated using compatible micromachining processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical components. One example of a MEMS element is a micro-optical component having a dielectric or metallized surface working in a reflection or refraction mode. Other examples of MEMS elements include actuators, detector grooves, and fiber grooves. In some examples, a MEMS spectrometer may include one or more micro-optical components (e.g., one or more reflectors or mirrors) that may be moveably controlled by a MEMS actuator. For example, the MEMS spectrometer may be fabricated using a deep reactive ion etching (DRIE) process on a silicon-on-insulator (SOI) substrate in order to produce the micro-optical components and other MEMS elements that are able to process free-space optical beams propagating parallel to the SOI substrate.

The spectrum <NUM> is input to a machine learning (ML) engine <NUM>, such as an AI engine, to generate a result <NUM> defining at least one parameter of the fluid <NUM>. For example, the result <NUM> may identify the fluid or obtain other parameters associated with the fluid, such as the concentration of the fluid, the energy content in the fluid, the total volatile organic compound, the amount of particulate matter in the fluid, the microparticles suspended in the fluid, or other suitable parameters. In some examples, the ML engine <NUM> may use correction and prediction models, such as chemometrics, Kalman filtering, etc., to predict or estimate the parameter(s). In some examples, the ML engine <NUM> may access an optional database <NUM> containing fluid data to generate the result <NUM>. For example, the fluid data stored on the database <NUM> may be utilized to train the ML engine <NUM>. In an example, the fluid data may contain spectrum parameters for known fluids and fluid concentrations. In some examples, the optical fluid analyzer <NUM> may include a memory on which the database <NUM> is stored.

<FIG> is a diagram illustrating exploded views of an example of an optical fluid analyzer <NUM> according to some aspects. The optical fluid analyzer <NUM> includes a fluid cell <NUM> (gas cell), a spectrometer <NUM>, a light source <NUM>, and a light source holder <NUM> configured to hold the light source <NUM> in place. The gas cell <NUM> includes three main parts: a top part <NUM>, a middle part <NUM>, and a bottom part <NUM>. The top part <NUM> is responsible for preserving the optical alignment between the light source <NUM> and the fluid cell <NUM> and includes an opening configured to receive a first optical window (glass window) <NUM>. The middle part <NUM> is the main part of the fluid cell <NUM> that is configured to receive a fluid. For example, the middle part <NUM> may be coupled to a fluid inlet to receive a fluid and a fluid outlet to pass the fluid out of the fluid cell <NUM>. For the fluid cell I/O (between the fluid inlet/outlet and the fluid cell), sealed quick connectors may be used to seal the flow of the fluids and to ease the installation of the air tubing. The middle part <NUM> may further be coupled to one or more optical coupling elements <NUM> configured to direct input light from the light source <NUM> into the fluid cell. In the example shown in <FIG>, the optical coupling element(s) include a ball lens <NUM> coupled between the first optical window <NUM> and the fluid cell <NUM>.

The bottom part <NUM> of the fluid cell <NUM> is responsible for preserving the optical alignments between the spectrometer <NUM> and the rest of the parts. The bottom part <NUM> includes walls surrounding the spectrometer <NUM> to provide a physical alignment of the spectrometer <NUM> with the remaining parts of the fluid cell <NUM>. The bottom part <NUM> further includes an opening configured to receive a second optical window (glass window) <NUM>. The first and second optical windows <NUM> and <NUM> are further configured to seal the fluid cell <NUM> from the top and bottom sides. In some examples, the first and second optical windows <NUM> and <NUM> may be flat optical windows, such as sapphire glass windows. The flat optical windows <NUM> and <NUM> are configured to allow the infrared spectrum to be transmitted with a very small absorption value. In some examples, the fluid cell parts <NUM>, <NUM>, and <NUM> may be nickel-plated to prevent corrosion due to some fluids.

When using a ball lens in a sealed optical setup, as shown in <FIG>, the ball lens <NUM> is inserted between the two flat optical windows <NUM> and <NUM>. The two flat optical windows <NUM> and <NUM> can seal the fluid cell <NUM> with the use of O-rings (not specifically shown in <FIG>). According to O-ring design guides, O-rings cannot be used directly with the ball lens <NUM> in examples in which the ball lens <NUM> is in contact with a flat surface (e.g., flat optical windows <NUM> and <NUM>) to maintain a homogeneous pressure over the surface contact area. Therefore, in some examples, ball seats may be used in lieu of O-rings to seal the fluid cell <NUM>. Ball seats may replace not only the O-rings, but the entire sealing system including the flat optical window <NUM>.

<FIG> are diagrams illustrating an optical fluid analyzer <NUM> including a ball seat sealing system according to some aspects. The optical fluid analyzer <NUM> includes a ball lens <NUM> surrounded by ball seats <NUM> and <NUM>. The inner surface curvature of the ball seats <NUM> and <NUM> is configured to match the lens surface curvature of the ball lens <NUM> to increase surface contact, thereby increasing the sealing efficiency. In some examples, the ball seats <NUM> and <NUM> may be formed of rubber.

The optical fluid analyzer <NUM> further includes a fluid cell (gas cell) <NUM>, an optical window <NUM>, a spectrometer <NUM>, a fluid inlet <NUM>, a fluid outlet <NUM>, and a light source <NUM>. An O-ring <NUM> is configured to seal the spectrometer <NUM>. The fluid inlet <NUM> and fluid outlet <NUM> are configured to allow a fluid (e.g., liquid, gas, or plasma) to enter and exit the fluid cell <NUM>. The ball lens <NUM> and ball lens seats <NUM> and <NUM> form an optical element configured to seal the fluid cell <NUM> on a first side thereof. In addition, the ball lens <NUM> is further configured to direct input light from the light source <NUM> into the fluid cell <NUM>. The optical window <NUM> is configured to seal the fluid cell <NUM> on a second side thereof opposite the first side and to direct output light from the fluid cell into the spectrometer <NUM>. The fluid cell <NUM> and spectrometer <NUM> may be assembled on a substrate <NUM> (e.g., a printed circuit board (PCB)). In some examples, a ML engine and associated database (e.g., memory), not shown for simplicity, may further be assembled on the substrate <NUM>. Various sensors, such as pressure sensors, temperature sensors, fluid flow sensors, and other suitable sensors may further be integrated on the substrate <NUM>.

In the example shown in <FIG>, the fluid cell <NUM> is a separate unit from the spectrometer <NUM>, such that each of the systems (optical, electrical, and mechanical) are separated from one another. This can lead to an increase in the overall size and in the number of components used. In addition, by separating the spectrometer <NUM> and the fluid cell <NUM> without any sealing between them, parasitic fluids can infiltrate the optical path, leading to incorrect reading. Therefore, in some examples, a package glass window may replace the fluid cell optical window <NUM> to be directly in contact with both the fluid and the spectrometer package.

<FIG> are diagrams illustrating an example of an optical fluid analyzer <NUM> including a package glass window sealing system according to some aspects. The optical fluid analyzer <NUM> includes a spectrometer <NUM> integrated within a package <NUM> that is assembled on a substrate <NUM> (e.g., a PCB). The package <NUM> includes an opening configured to receive a package glass window <NUM>.

The optical fluid analyzer <NUM> further includes a ball lens <NUM>, ball lens seats <NUM> and <NUM> surrounding the ball lens <NUM>, and a fluid cell <NUM>. The ball lens <NUM> and ball lens seats <NUM> and <NUM> form an optical element configured to seal the fluid cell <NUM> on a first side thereof. In addition, the ball lens <NUM> is further configured to direct input light from a light source (not shown) into the fluid cell <NUM>. The package glass window <NUM> is configured to seal the fluid cell <NUM> on a second side thereof opposite the first side and to direct output light from the fluid cell <NUM> into the spectrometer <NUM>. In particular, the package glass window <NUM> is configured to provide sealing directly between the fluid cell <NUM> and the spectrometer <NUM>. An O-ring <NUM> may be used to maintain the sealing between the package glass window <NUM> and the fluid cell <NUM>, thereby preventing parasitic leakage of the fluid.

In examples in which a ball lens is used as an optical coupling element to couple the input light into the fluid cell (e.g., as shown in any of <FIG>, <FIG>, <FIG>, or <FIG>), a slight dislocation of the lens can cause discrepancies in the optical signal and overall spectrum measured. For example, if a housing containing the ball lens is fabricated with a tight clearance between the ball lens and the housing, any variation may prevent the top part of the housing from being assembled with the lower part of the housing. This in turn may lead to a fluid leakage. Therefore, in some examples, a rubber spacer or spring may be added to fix the position of the ball lens.

<FIG> are diagrams illustrating examples of ball lens configurations according to some aspects. In <FIG>, a ball lens <NUM> is positioned in a housing <NUM> and configured to seal a fluid cell <NUM> on a first side thereof. An optical window <NUM> (e.g., a flat sapphire window) is further configured to seal the fluid cell <NUM> on a second side thereof opposite the first side. In <FIG>, a rubber spacer <NUM> is shown coupled between the ball lens <NUM> and the flat optical window <NUM>. In <FIG>, a spring <NUM> is shown coupled between the ball lens <NUM> and the flat optical window <NUM>. Neither the rubber spacer <NUM> nor the spring <NUM> block the fluid flow through the fluid cell <NUM>. In addition, each of the rubber spacer <NUM> and the spring <NUM> produce a pressure on the ball lens <NUM>, which in turn, fixes the ball lens <NUM> in position, thus preventing any change in its position due to motions or vibrations of the housing <NUM>.

In the examples shown in <FIG>, the optical coupling element may include a light source and a ball lens that focuses the light into the MEMS spectrometer. This design provides simplicity since a balls lens is the only optical component and the ball lens is used in sealing. This design may be used, for example, for gases where there is no difference between the gases refractive index and air, so the flow of gases may not affect the focusing and optical coupling of the design. However, measuring liquids or other fluids that have significant variation in the refractive index may affect the optical coupling. Therefore, in some examples, the optical coupling may be performed by a collimated design in which the fluid type may not affect the optical coupling.

<FIG> are diagrams illustrating examples of collimated optical coupling designs according to some aspects. In the example shown in <FIG>, the optical coupling is performed using a collimated setup in which the fluid sample type does not impact the optical coupling. <FIG> illustrates a collimated optical coupling design using two ball lenses <NUM> and <NUM>, whereas <FIG> illustrates a collimated optical coupling design using two half-ball lenses <NUM> and <NUM>. In each design, the two ball lenses <NUM> and <NUM> or two half-ball lenses <NUM> and <NUM> couple input light from a light source <NUM> into a fluid cell <NUM> on a first side thereof and receive and couple output light from the fluid cell via a second side thereof into a spectrometer <NUM>. The ball lenses <NUM> and <NUM> or half-ball lenses <NUM> and <NUM> may provide not only optical coupling, but also sealing of the fluid cell <NUM> (e.g., using ball lens seats or O-rings, as described above). The two ball lenses <NUM> and <NUM> design in <FIG> is less sensitive and more compact in terms of distance between the infrared source <NUM> and the lenses <NUM> and <NUM>, while the two half-ball lenses <NUM> and <NUM> design is easier in term of sealing the fluid cell <NUM> (e.g., O-rings may be used for sealing instead of ball lens seats).

<FIG> is a diagram illustrating another example of a collimated optical coupling design according to some aspects. In the example shown in <FIG>, the ball or half-ball lenses can be replaced by Plano convex lenses <NUM> and <NUM>. In addition, the collimated setup uses a reflector <NUM> inserted behind the light source <NUM> to collect back rays of the light source and reflect the back rays towards the Plano convex lens <NUM> for coupling into a fluid cell <NUM> to nearly double the optical power. In some examples, the Plano convex lenses <NUM> and <NUM> may be calcium fluoride lenses with focal lengths <NUM> and <NUM> of <NUM> to accommodate a fluid path length <NUM> of <NUM>. It should be understood that the focal lengths <NUM> and <NUM> and fluid path length <NUM> are variable and not limited to the examples provided herein. In some examples, the Plano convex lenses <NUM> and <NUM> may provide sealing of the fluid cell <NUM>. In other examples, additional flat optical windows may be used for sealing the fluid cell <NUM>.

<FIG> is a diagram illustrating another example of a collimated optical coupling design according to some aspects. In the example shown in <FIG>, the collimating design includes two off-axis parabolic mirrors <NUM> and <NUM>. The off-axis parabolic mirror <NUM> is configured to receive input light from a light source <NUM> and reflect (redirect) the input light into a fluid cell <NUM> on a first side thereof. In addition, the off-axis parabolic mirror <NUM> is configured to receive output light from the fluid cell <NUM> on a second side thereof and to reflect (redirect) the output light into a spectrometer <NUM>. The fluid cell <NUM> may be sealed using flat optical windows (not shown), as described above.

The off-axis parabolic mirrors <NUM> and <NUM> provide a wide spectrum range of metallic reflection and avoid the Fresnel optical loss of the lens designs shown in <FIG>, and <FIG>. In addition, the mirrors <NUM> and <NUM> may be manufactured by plastic molding that allows high volume with low cost. In some examples, a single plastic mold including both mirrors <NUM> and <NUM> may be used to accommodate any sensitivity of the alignment in the design shown in <FIG>.

In some examples, the off-axis parabolic mirror <NUM> has a focal length of <NUM>, and the off-axis parabolic mirror <NUM> has a focal length of <NUM>. In this example, a distance <NUM> between the light source <NUM> and the off-axis parabolic mirror <NUM> may be <NUM> and the off-axis parabolic mirrors <NUM> and <NUM> may each have a width <NUM> of <NUM> with a fluid cell length <NUM> of <NUM>. It should be understood that the focal lengths, distance <NUM>, width <NUM> of the mirrors <NUM> and <NUM>, and fluid cell length <NUM> are variable, and not limited to the examples provided herein.

<FIG> is a diagram illustrating another example of a collimated optical coupling design according to some aspects. In the example shown in <FIG>, the collimating design includes an off-axis parabolic mirror <NUM> and a lens <NUM>. The off-axis parabolic mirror <NUM> is configured to receive input light from a light source <NUM> and reflect (redirect) the input light into a fluid cell <NUM> on a first side thereof. In addition, the lens <NUM> is configured to receive output light from the fluid cell <NUM> on a second side thereof and to reflect (redirect) the output light into a spectrometer <NUM>. In some examples, the lens <NUM> may be a calcium fluoride lens. The fluid cell <NUM> may be sealed using flat optical windows (not shown) or using a combination of a flat optical window adjacent to the off-axis parabolic mirror <NUM> and the lens <NUM>. In some examples, the lens <NUM> may be coated to facilitate calibration of the optical fluid analyzer.

In some examples, the off-axis parabolic mirror <NUM> has a focal length of <NUM> and the lens <NUM> has a focal length of <NUM>. In this example, a distance <NUM> between the light source <NUM> and the off-axis parabolic mirror <NUM> may be <NUM> and the off-axis parabolic mirror <NUM> may have a width <NUM> of <NUM> with a fluid cell length <NUM> of <NUM>. It should be understood that the focal lengths, distance <NUM>, width <NUM> of the mirrors <NUM> and <NUM>, and fluid cell length <NUM> are variable, and not limited to the examples provided herein.

<FIG> are diagrams illustrating an optical coupling design, according to the invention, for calibration of the optical fluid analyzer according to some aspects. The optical coupling design shown in <FIG> includes a ball lens <NUM> having a filter response coating <NUM> on opposing ends thereof. The center area of the ball lens <NUM> is not coated with the filter response coating <NUM>. The coating <NUM> absorbs all wavelengths except for a reference wavelength λo used by the calibration. The response of the coating <NUM> is shown in <FIG>.

<FIG> illustrate modes of operation of a coated ball lens <NUM> according to the invention. In a first mode, as shown in <FIG>, the filter response coating <NUM> of the ball lens <NUM> is out of a light path <NUM> of input light from a light source (not shown). Therefore, no absorption of the input light occurs and the spectrum reflects the absorption of the fluid in a fluid cell (not shown). In a second mode, as shown in <FIG>, the light path <NUM> of the input light passes through the filter response coating <NUM> of the ball lens <NUM>, and as a result, absorption occurs producing the spectrum shown in <FIG>. The second mode may thus be referred to as a calibration mode. For example, in the calibration mode, the value of the wavelength λo may be compared to a reference design value using, for example, digital signal processing. Calibration and drift correction may then be performed based on the comparison. For example, the optical fluid analyzer may be configured to calibrate the machine learning engine during the calibration mode.

<FIG> is a diagram illustrating an exemplary mode-switching operation according to some aspects. In the example shown in <FIG>, a ball lens <NUM> includes a filter response coating <NUM> on opposing ends thereof, as in <FIG>, <FIG>. A rotation device <NUM> is coupled to the ball lens <NUM> and configured to rotate the ball lens <NUM> between a first orientation (e.g., the first mode shown in <FIG>) in which the input light passes through the ball lens <NUM> without passing through the filter response coating <NUM> and a second orientation (e.g., the second mode shown in <FIG>) in which the input light passes through the filter response coating <NUM> of the ball lens <NUM>. For example, the rotation device <NUM> may include springs and fingers that are controlled by the optical fluid analyzer to produce a <NUM> degree rotation of the ball lens <NUM> between the two modes of operation.

<FIG> is a flow chart illustrating an exemplary process for calibrating an optical fluid analyzer including a coated ball lens according to some aspects. At block <NUM>, the optical fluid analyzer may enter a calibration mode of the device. At block <NUM>, the optical fluid analyzer may mechanically rotate the coated ball lens (e.g., using the rotation device shown in <FIG>) <NUM> degrees to the second orientation shown in <FIG>, such that the filter response coating of the ball lens is within the light path of the input light from the light source. At block <NUM>, the optical fluid analyzer may obtain a spectrum when the coated ball lens is in the second orientation. At block <NUM>, the optical fluid analyzer may compare the spectrum to a reference wavelength. At block <NUM>, the optical fluid analyzer may obtain correction factors and calibration parameters based on the comparison. The correction factors and calibration parameters may then be used to train the machine learning engine. At block <NUM>, the optical fluid analyzer may mechanically rotate the coated ball lens (e.g., using the rotation device shown in <FIG>) <NUM> degrees to the first orientation shown in <FIG>, such that the filter response coating of the ball lens is outside the light path of the input light from the light source to enable the optical fluid analyzer to obtain a spectrum of the fluid sample under test.

<FIG> are diagrams illustrating an example of an optical coupling design with variable optical path length according to some aspects. The optical coupling design includes two optical elements <NUM> and <NUM> for coupling input light into a fluid cell <NUM> on a first side thereof and coupling output light from the fluid cell <NUM> via a second side thereof. The optical elements <NUM> and <NUM> may include, for example, flat optical windows, ball lenses, half-ball lenses, Plano convex lenses, or other suitable optical coupling elements. To overcome the challenge of parasitic interference effect in a fluid cell <NUM> due to the multiple reflections of light and the microscale path length <NUM> in the fluid cell (e.g. <NUM> up to <NUM>), at least one of the optical elements (e.g., optical element <NUM>) can be coupled to an actuator <NUM> (e.g., a micro/actuation mechanism) that is configured to cause motion of the optical element <NUM> to continually vary the optical path length with motion d(t) in the fluid cell <NUM> around a nominal value do, as shown in <FIG>. The continuous motion of the optical element <NUM> results in dithering of the optical path length, such that the average value of d(t) is zero, as shown in by comparison between <FIG> (with no oscillatory motion) and 14C (with oscillatory motion). In other examples, dithering of the optical path length may be achieved by electro-optic effect and/or thermo-optic effect applied on the optical element <NUM>. For example, an electric field may be applied across the optical element <NUM> or a micro heater may be integrated with the optical element <NUM>.

<FIG> is a diagram illustrating an example of a fluid cell design according to some aspects. The fluid cell design includes two optical elements <NUM> and <NUM> configured to seal a fluid cell <NUM> on either side thereof. To overcome the stiction of the fluid, for example, oil samples, within the fluid cell <NUM>, a coating <NUM> can be applied on an internal surface (facing the fluid cell <NUM>) of at least one of the optical elements <NUM> and <NUM> to repel the fluid (e.g., prevent stiction of the fluid). In some examples, the coating <NUM> can be hydrophobic or omni-phobic. As a result, the fluid may be purged easily without a need for a consumables cleaning solution. In some examples, the coating <NUM> can be also applied on interior walls <NUM> in the fluid cell <NUM>.

<FIG> is a diagram illustrating an example of an optical fluid analyzer <NUM> integrated with other sensors according to some aspects. The optical fluid analyzer <NUM> includes a MEMS based FTIR fluid analyzer <NUM> (e.g., including a light source, optical elements, fluid cell, and spectrometer (interferometer/detector)), artificial intelligence (AI) engine <NUM> (e.g., ML engine), and database <NUM> that are integrated with one or more other sensors. Examples of sensors include, but are not limited to, a pressure sensor <NUM>, a flow (fluid flow) sensor <NUM>, a temperature sensor <NUM>, and a humidity sensor <NUM>). The sensors <NUM>-<NUM> may be synchronized together and controlled via integrated electronics and synchronization signal circuitry <NUM> to sense the fluid at the same time as the MEMS based FTIR fluid analyzer <NUM> obtains a spectrum of the fluid. The output (e.g., sensor data related to the fluid in the fluid cell) of each sensor <NUM>-<NUM> may be input to the AI engine <NUM>, along with the spectrum of the fluid to aid the AI engine <NUM> in predicting the fluid properties and specifications. The AI engine may further be trained with fluid data in the database <NUM> to produce results <NUM> related to the fluid.

<FIG> is a diagram illustrating another example of an optical fluid analyzer <NUM> according to some aspects. The optical fluid analyzer <NUM> includes a light source <NUM>, an optical coupling element <NUM>, a microfluidic cell <NUM> configured to receive a fluid under test, and a spectrometer <NUM>. In the example shown in <FIG>, the microfluidic cell <NUM> is placed over the spectrometer <NUM>. Thus, the microfluidic cell <NUM> can act as a transmission cell that includes optical windows configured to seal the microfluidic cell <NUM> and pass light through the microfluidic cell. In addition, the light source <NUM> with a compact form factor can be integrated above the microfluidic cell <NUM>.

<FIG> is a diagram illustrating another example of an optical fluid analyzer <NUM> according to some aspects. The optical fluid analyzer includes a light source <NUM>, an optical coupling element <NUM>, a microfluidic cell <NUM>, and a spectrometer <NUM>. The spectrometer <NUM> may be integrated into an optical package <NUM>. The microfluidic cell <NUM> may further include optical windows configured to seal the microfluidic cell <NUM> and to pass light through the microfluidic cell <NUM>. In addition, microfluidic cell <NUM> may further act as a glass package window of the package <NUM>. Thus, the microfluidic cell/glass package window can be configured to seal the spectrometer <NUM> (e.g., MEMS based FTIR spectrometer and detector). From an assembly point of view, the microfluidic cell <NUM> can be on the same production line as the optical package for better assembly and production handling.

<FIG> is a diagram illustrating an example of optical fluid analyzer <NUM> configured for viral detection according to some aspects. In some examples, the optical fluid analyzer <NUM> can be configured to measure the spectrum of a patient breath sample and predict the type of viral infection of the patient. For example, using different chemometric techniques, the ML engine (AI engine) of the optical fluid analyzer may predict the viral type from the absorption bands of the spectrum. To measure the breath sample, the optical fluid analyzer <NUM> can include an input tube <NUM> through which a patient can blow air from their mouth into the fluid cell of the optical fluid analyzer <NUM>.

The invention is solely defined by the appended claims.

Claim 1:
An optical fluid analyzer, comprising:
a light source (<NUM>) configured to generate input light (<NUM>);
a fluid cell (<NUM>) configured to receive a fluid (<NUM>);
a first optical element (<NUM>) configured to seal the fluid cell (<NUM>) on a first side thereof, the first optical element (<NUM>) further configured to direct the input light (<NUM>) into the fluid cell (<NUM>) on the first side thereof, wherein the first optical element (<NUM>) comprises a ball lens (<NUM>) coupled between the light source (<NUM>) and the first side of the fluid cell (<NUM>), the ball lens (<NUM>) being coated with a filter response coating (<NUM>) on opposing ends thereof;
a second optical element (<NUM>) configured to seal the fluid cell (<NUM>) on a second side thereof opposite the first side, the second optical element (<NUM>) further configured to receive output light (<NUM>) from the fluid cell (<NUM>) via the second side thereof;
a spectrometer (<NUM>) configured to receive the output light (<NUM>) via the second optical element (<NUM>) and to obtain a spectrum of the fluid based on the output light;
a rotation device (<NUM>) coupled to the ball lens (<NUM>) and configured to rotate the ball lens (<NUM>) between a first orientation in which the input light passes through the ball lens (<NUM>) without passing through the filter response coating (<NUM>) and a second orientation in which the input light passes through the filter response coating (<NUM>) of the ball lens (<NUM>); and
a machine learning engine (<NUM>) configured to receive the spectrum and to generate a result defining at least one parameter of the fluid, wherein the optical fluid analyzer is configured to operate in a calibration mode to calibrate the machine learning engine (<NUM>) when the ball lens (<NUM>) is in the second orientation.