Patent Application
20220091116
This patent document relates to optical sensing technologies.
Optical sensors can use optical fiber either as the sensing element or as a means of relaying signals from a remote sensor to the electronics that process the signals. They allow direct measurements of liquids, powders, and flames, as well as solids.
Disclosed are methods, devices and applications pertaining to an optical fiber sensor having a mechanically processed and chemically functionalized optical fiber tip or optical fiber section to optically detect certain properties in a fluid flow based on optical evanescent coupling in transmissive or reflective mode.
In an embodiment of the disclosed technology, an optical sensor device for detecting a chemical analyte include a light source configured to generate probe light having a first wavelength spectrum, an optical fiber sensor probe including a mechanically processed optical fiber segment which is chemically functionalized to include a sensing material formed on exterior of the fiber segment, the optical fiber sensor probe coupled to receive and guide the generated probe light inside the optical fiber sensor probe while allowing optical evanescent coupling between probe light guided inside the optical fiber sensor probe and the sensed material, and a detector coupled to the optical fiber sensor probe to optically detect the guided probe light to obtain information on a material property of the sensed material.
In another embodiment of the disclosed technology, an optical fiber sensor for detecting a chemical analyte includes a first optical fiber segment including a first core and a first cladding surrounding the first core configured to cause light to be confined to the first core, a second optical fiber segment including: a second core connected to the first core; a second cladding surrounding the second core to cause an evanescent field to be generated at a boundary between the second core and the second cladding; and a sensing material layer disposed on the second cladding to cause the evanescent field to interact with the chemical analyte through the sensing material layer. The second cladding is thinner than the first cladding.
In another embodiment of the disclosed technology, a flow cell for process fluid flow analysis includes a liquid flow path through which an analyte flows, an optical path through which a waveguide is arranged to direct a light beam toward the analyte, and an evanescent fiber segment arranged at a crosspoint between the liquid flow path and the optical path to optically detect properties of the analyte. The evanescent fiber segment includes a fiber having a partially removed cladding on a core and a sensing material layer disposed on the partially removed cladding.
Those and other implementations and features of the disclosed technology are described in more detail in the drawings, the description and the claims.
There is a need to more reliably and affordably monitor pH in biopharmaceutical flow processes, and spectral interrogation using low-cost sensory films is a way to achieve this. However, some existing optical methods direct probe light to pass through a fluid flow to be measured. This direct interaction between the probe light and the fluid can lead to changes in the probe light by changes associated with the pH level of the fluid and also changes by other fluid properties not associated with the pH level, such as influence from sample color, turbidity, cross-fluorescence, and others. This direct interaction between the probe light and the fluid creates the potential for optical errors in pH measurement from sample color, turbidity and sediment, cross-fluorescence, etc. Some corrective techniques can be applied to account for these variations and provide the appropriate corrections but various corrective measures may not be able to fully remove such non-pH influences.
The technology disclosed in this patent document provides an optical waveguide such as a fiber probe to spatially confine the probe light inside the fiber probe by inserting the fiber probe into a target fluid to be measured without directing the probe light into the target fluid. A section of the exterior surface of the fiber probe is processed to have a pH-sensitive material which is in direct contact with the target fluid and will change an optical property of the material in response to a change in the pH value of the fluid. This change in the optical property of the material, when located in the evanescent field reach of guided probe light in the fiber probe, can be optically detected by and carried by the guided probe light if the fiber probe is structured to permit such evanescent interaction. The guided probe light in the fiber probe, upon evanescently interacting with the pH-sensitive material, carries information on the change in the pH level of the fluid imparted to the change in the optical property of the material and remains in the fiber probe without being in contact with the fluid. Optical detection of the guide probe light in the fiber probe can be performed to measure the pH level of the fluid.
As shown in
An example specification of the optical fiber sensor is shown in Table 1 below:
The performances of the optical fiber sensor implemented based on the example specification above are shown in Table 2 below:
The optical fiber sensor implemented based on some embodiments of the disclosed technology can bypass interferences and provide a more stable measurement of the fluid by isolating photons within the optical fiber. The analytical light no longer directly enters the process fluid or uses it as a medium. Rather, the bulk of the photons reside within the installed sensory fiber (e.g., one or more roughened fiber segments with colorimetric or fluorescent coating), and the evanescent interaction with the color-changing sensor film is captured and relayed back to the detector. This provides a more stable measurement which will not falter as optical properties of the process fluid change.
The optical fiber sensor implemented based on some embodiments of the disclosed technology can be used for pH sensor chemistry (colorimetric, bromocresol green), moisture sensor chemistry (colorimetric, cobalt chloride degrees of hydration), and oxygen sensor chemistry (fluorescent, ruthenium and platinum porphyrins).
In an embodiment of the disclosed technology, the functionalized optical evanescent sensor can be implemented to deal with transmissive measurements. In another embodiment of the disclosed technology the functionalized optical evanescent sensor can be implemented to deal with reflective measurements by using a reflective layer of the optical fiber segment. Reflective material added to tip can make probe extremely immune to movement, ambient light, and sample color and turbidity. Unlike typical evanescent, side-coated fibers/sensors, low-cost plastic fibers can be used to achieve strong absorbance signals through just several fiber treatments. In some implementations, a roughened portion of a plastic fiber can be used to achieve an evanescent absorbance measurement.
The optical sensor implemented based on some embodiments of the disclosed technology includes a mechanically processed and chemically functionalized optical fiber segment to utilize evanescent waves in measuring characteristics of chemical analytes. This measurement is based on the interaction between the evanescent wave and the surrounding environment. When light passes through the mechanically processed (e.g., side-polished) optical fiber segment, a fraction of the radiation can extend a small distance (an evanescent field) from the mechanically processed region. This evanescent wave can interact with the chemical analytes through a chemically functionalized layer disposed on a mechanically processed side of the optical fiber. The evanescent field that enters a waveguide from the mechanically processed and chemically functionalized optical fiber segment can be collected by a detector to analyze the characteristics of the chemical analytes.
Some embodiments of the disclosed technology can be implemented to utilize a mechanically processed and chemically functionalized optical fiber installed into a liquid flow cell for interrogation of some aspect of the fluid. A fiber made of plastic or glass is roughened or “knurled” around the outer circumference of the fiber for a specified segment length, which may vary and can also include multiple segments. In an example, a 1000 μm plastic (PMMA) fiber can be used and it can be roughened using 280-grit barrel sanders.
This roughened portion of the fiber is functionalized or coated with an optically active sensory film. Some embodiments of the disclosed technology can be used to implement an optical pH sensor using colorimetric pH sol-gel formulation, moisture/humidity-sensitive colorimetric compounds, and/or oxygen-sensitive fluorescent compounds. The optical pH sensor is coupled to a light source. Light generated at the light source is transmitted to a mechanically processed and chemically functionalized optical fiber segment of the optical pH sensor. Based on the pH of the chemical analytes, a certain amount of light may absorb at a certain wavelength range or ranges. Such partially absorbed light travels to the detector and is compared with a previously taken reference to obtain a pH value based on a predetermined algorithm. For example, in the case where the indicator molecules absorb light when exposed to a basic solution, the partially absorbed light is compared to a reference taken as a zero absorbance across the entire spectrum to represent all indicator molecules in an acid form.
After the sensor film has cured on the roughened portion, the fiber may be mechanically integrated into a flow cell form factor in transmissive or reflective mode. The roughened sensory portion is positioned such that it is in contact with the process fluid. An example schematic of the flow cell is shown in
Pharmaceutical processes are notorious for requiring precise monitoring and control of pH to ensure desired products and yields are obtained. The mechanically processed and chemically functionalized optical fiber tip or fiber section implemented based on some embodiments of the disclosed technology can be used in pharmaceutical processes to offer a fast and consumable approach to pH monitoring in such a process environment.
In some embodiments of the disclosed technology, the functionalized optical evanescent sensor can be used for real-time monitoring of process fluids in their flow condition. The immediate use described here pertains to optical sensing of fluid pH. This provides a low-cost and minimal-interface approach to optical monitoring of a process fluid flow. The components can be integrated into disposable plastic flow cells, and can be easily coupled to more permanent detection hardware. The evanescent interrogation of the sensory coating avoids many of the downfalls seen with traditional transmissive approaches, including noise/errors from sample turbidity, color, and other interferences.
In addition to the pH sensor prototypes discussed here, functioning sensors implemented based on some embodiments of the disclosed technology may also be built for the optical detection of molecular oxygen and of humidity/moisture/aqueous-content. This may quickly be expanded into other desired analytes.
In
Implementations of the subject matter and the functional operations described in this patent document can be implemented in various systems, digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible and non-transitory computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them. The term “data processing unit” or “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).
Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.
It is intended that the specification, together with the drawings, be considered exemplary only, where exemplary means an example. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Additionally, the use of “or” is intended to include “and/or”, unless the context clearly indicates otherwise.
While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.
Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.
This patent document is a continuation of International Application No. PCT/US20/36004, entitled “OPTICAL SENSING BASED ON FUNCTIONALIZED EVANESCENT FIBER SENSOR FOR PROCESS FLUID FLOW ANALYSIS” filed on Jun. 3, 2020 and which claims priority to and the benefits of U.S. Provisional Patent Application No. 62/856,558 entitled “OPTICAL SENSING BASED ON FUNCTIONALIZED EVANESCENT FIBER SENSOR FOR PROCESS FLUID FLOW ANALYSIS” filed on Jun. 3, 2019. The entire contents of the aforementioned patent application are incorporated by reference as part of the disclosure of this patent document.
| Number | Date | Country | |
|---|---|---|---|
| 62856558 | Jun 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US20/36004 | Jun 2020 | US |
| Child | 17541179 | US |
