Determining wettablity characteristics of a fluid-fluid-solid sample

Provided are embodiments for a system for determining wettability of fluid-fluid-solid systems. The system includes a confocal optical microscope and a storage medium, the storage medium being coupled to a processor. The processor is configured to perform a scan of a sample of a multi-phase system using the confocal optical microscope, wherein a phase defines a structural phase of matter, identify each phase of the sample, and measure a three-phase contact line for the sample, wherein the three-phase contact line is along an interface of first fluid and a second fluid and an interface of a second fluid and solid. The processor is configured to obtain one or more characteristics from the sample based at least in part on the three-phase contact line, and provide the one or more characteristics for the sample. Also provided are embodiments for a method for determining the wettability of fluid-fluid-solid systems.

BACKGROUND

The present invention generally relates to using computing systems and measurement tools to determine three-phase system characteristics, and more specifically to a computer-implemented methods and computer systems configured and arranged to determine the wettability of fluid-fluid-solid systems.

Wettability is a property that describes the bonding or adherence of two materials. For example, wettability describes the ability of a fluid to maintain contact with a solid surface. The wettability typically is represented by the contact angle which can be measured from a sample to determine the degree the fluid is wetting the solid surface. The contact angle is often used to quantify the wettability providing a concrete physical representation of the wettability. As the conditions of a solution or mixture change the contact angle changes based on the intermolecular interactions between the fluid and solid. This can be useful for applications such as fossil fuel recovery, semiconductor manufacturing, agriculture, food and beverage, textile, metal processing and printing industries to name a few. When a first and second fluid comes into contact with a surface, the contact angle is established which is an indicator of the wettability characteristics. The contact angle provides one of many ways to quantify the wettability of a fluid.

SUMMARY

Embodiments of the present invention are directed to a method for determining the wettability of fluid-fluid-solid systems. A non-limiting example of the method includes performing, by a measuring device, a scan of a sample of a multi-phase system, wherein a phase defines a structural phase of matter, identifying each phase of the sample, and measuring a three-phase contact line for the sample, wherein the three-phase contact line is along an interface of first fluid and a second fluid and an interface of a second fluid and solid. The method also includes obtaining, by a computing device, one or more characteristics from the sample based at least in part on the three-phase contact line, and providing, by the computing device, the one or more characteristics for the sample.

Embodiments of the present invention are directed to a system for determining the wettability of fluid-fluid-solid systems. A non-limiting example of the system includes a confocal optical microscope and a storage medium, the storage medium being coupled to a processor. The processor is configured to perform a scan of a sample of a multi-phase system using the confocal optical microscope, wherein a phase defines a structural phase of matter, identify each phase of the sample, and measure a three-phase contact line for the sample, wherein the three-phase contact line is along an interface of first fluid and a second fluid and an interface of a second fluid and solid. The processor is configured to obtain one or more characteristics from the sample based at least in part on the three-phase contact line, and provide the one or more characteristics for the sample.

Embodiments of the invention are directed to a computer program product for determining the wettability of fluid-fluid-solid systems, the computer program product comprising a computer readable storage medium having program instructions embodied therewith. The program instructions are executable by a processor to cause the processor to perform a method. A non-limiting example of the method includes controlling an optical microscope to perform a scan of a sample of a multi-phase system, wherein a phase defines a structural phase of matter, identifying each phase of the sample, and measuring a three-phase contact line for the sample, wherein the three-phase contact line is along an interface of first fluid and a second fluid and an interface of a second fluid and solid. The method also includes obtaining, by a computing device, one or more characteristics from the sample based at least in part on the three-phase contact line, and providing, by the computing device, the one or more characteristics for the sample.

DETAILED DESCRIPTION

Turning now to an overview of technologies that are more specifically relevant to aspects of the invention, the wettability property of fluids is used to provide useful information in a variety of applications. Wettability is the degree with which fluids maintain contact with a solid surface. Wettability results from the molecular interactions between the fluids and the solid. The wettability of the system can be determined by measuring a contact angle between the fluid-fluid interface and the fluid-solid interface which is impacted by balancing the adhesive and cohesive forces in the system. That is, as the tendency for a droplet to spread over a solid surface increases, the contact angle decreases. Therefore, the contact angle provides an indication of the wettability characteristic of the fluid.

In order to change the contact angle, a fluid having known properties can be introduced into the mixture to increase/decrease the wettability characteristic to obtain the desired qualities for the droplet.

With reference toFIGS. 1-3, the contact angle is typically used at the figure-of-merit for wettability. A droplet of fluid1(F1) is dispersed in fluid2(F2) which is in contact with a solid surface (S). The shape of the F1-F2interface and the manner in which it intersects with the solid interface determines the wettability characteristic of the three-phase system (F1-F2-S). The contact angle is often measured from a side perspective of the droplet using an examination microscope. Different types of microscopes can be used to analyze and measure the contact angle formed by the droplet. It is further analyzed to determine the three-phase contact line using analog or digital methods.

FIG. 1depicts a first fluid F1, a second fluid F2, and a solid surface S. The contact angle of the tangent line between the F1-F2interface and the solid surface S as shown inFIG. 1is greater than 90 degrees. In this scenario, it is said the fluid F1has a low wettability characteristic.FIG. 2depicts a first fluid F1, a second fluid F2, and a solid surface S. The contact angle of the tangent line between the F1-F2interface and the solid surface S as shown inFIG. 2is less than 90 degrees. In this scenario, it is said the fluid F1has a high wettability characteristic.FIG. 3depicts the contact angle F1-F2intersects S at a right angle, where in this scenario the system is said to be neutrally wet.

However, the above techniques are limited to fluid F2existing in the gaseous phase. That is, the existing techniques are limited to analyzing liquid droplets in vapor/gas setting. In addition, existing techniques obtain 2D silhouettes of the sample where the 2D nature of the acquired data oversimplifies the wetting behavior of most three-phase systems by assuming symmetries where none exist. As shown in each of theFIGS. 1-3, the sample is assumed to be a spherical cap. This occurs when performing the contact angle analysis using traditional techniques.

Turning now to an overview of the aspects of the invention, one or more embodiments of the invention address the above-described shortcomings of the prior art by providing techniques to determine the wetting properties of fluid-fluid-solid systems in a variety of scenarios. For example, a scenario can include a first fluid that is in a liquid phase, a second fluid contacting the first fluid that is in either gas or liquid phase, regardless of which fluid (F1or F2) is denser. Also, the techniques provide the ability to determine wetting properties for a fluid interface that is or is not assumed to be a spherical cap, where the fluid interface is not symmetric with respect to any plane or axis.

The contact angle will be measured by an examination microscope. The contact angle is measured optically by taking a sideways-perspective image of the droplet sample and analyzing the three-phase contact line.

The above-described aspects of the invention address the shortcomings of the prior art by implementing a method and system that leverages tomography to perform measurements to obtain a number of wettability characteristics.

Turning now to a more detailed description of aspects of the present invention,FIGS. 4A and 4Bdepict various examination techniques that can be used to analyze samples in accordance with one or more embodiments of the invention.FIG. 4Aillustrates a sample F1, wherein the sample contains a 3-phase sample F1(fluid-fluid-S.FIG. 4Adepicts a droplet F1, a second fluid F2, and a solid surface S. The microscope410is positioned above the sample and is configured to focus on different depths of the sample F1to obtain a plurality of scans of the sample. After obtaining the plurality of scans, the individual images are combined to form a 3D image of the sample. The 3D imaging of the sample F1allows an accurate representation of the sample that can be used to perform the measurement. The droplet is no longer assumed to be a spherical cap as in conventional techniques. Although the droplet sample F1is shown as a spherical cap inFIGS. 4A and 4B, this is only an illustrative example and is not intended to limit the capability of the techniques provided herein.

In one or more embodiments of the invention, the measurements and scans can be obtained using a confocal laser scanning microscope attached to a spectroscopic unit which allows for the spectral analysis of the light emanating from the position of the laser focus. In some embodiments of the invention, the measurements and scans are obtained using a confocal microscope attached to a camera unit that allows for capturing light emanating from the focus plane.

FIG. 4Bprovides an inverted arrangement where the microscope420is positioned below the sample. InFIG. 4B, the solid S is transparent which enables the microscope420to obtain a number of scans and measurements of the sample F1.

FIG. 5depicts a number of scans500that have been obtained from sample, such as the sample F1shown inFIGS. 4A and 4B. The bottom most layer as shown is the solid portion of the 3-phase system. The microscope can begin the scanning procedure at the bottom most layer and then continue to measure the additional layers of the sample to obtain a full set of images for the sample. As shown, the sample/droplet is not a perfect sphere which is assumed when using traditional techniques. Because an accurate depiction of the system is obtained by the microscope a better measurement for the contact angle can be obtained by using the techniques described herein. Each of the layers can be combined and used to obtain a 3D representation of the 3-phase system. It should be understood that the four layers shown inFIG. 5are only an example and any number of scans can be obtained by the microscope or scanning device to obtain a 3D rendering of the sample. In addition, it should be understood the sample can also be scanned from a top-down approach instead of a bottom-up approach as described.

Now referring toFIG. 6, a flowchart of a method600in accordance with one or more embodiments of the invention is shown. The process begins at block602where a sample is loaded onto a microscope for examination. In one or more embodiments of the invention, the microscope can be the measure device802as shown inFIG. 8. At block604the microscope focuses on a surface S of the sample and proceeds to block606to determine whether the microscope is in focus on the particular layer. If so (“Yes” branch), the method600proceeds to block608. Otherwise (“No” branch), the method600returns to block604to attempt to re-focus the microscope on the surface of the sample. After acquiring the image at block608, a plurality of image slabs is obtained from the sample at block610. In one or more embodiments of the invention, the plurality of image slabs are provided to a computing device806which is used to further process the image slabs. The image acquisition is repeated, as shown at block612, until the complete sample has been acquired layer-by-layer. At block614the plurality of image slabs are combined to form the 3D tomography (block616). That is, the computing device806further processes the plurality of image slabs to form the 3D tomography. At block618, the results can be displayed on a display for inspection. For example, the results can be displayed on a display on the computing device806or the results can be transmitted and displayed on different display device.

Now referring toFIG. 7, a flowchart of a method700in accordance with one or more embodiments of the invention is shown. The method700begins by loading the tomography to obtain data from the sample as shown at block702. In one or more embodiments of the invention, the optical tomography is loaded into a computing device806such as that shown inFIG. 8using a digital file representing the tomography. The digital tomography may consist of an image dataset containing a set of voxels (volume pixels) arranged in three-dimensional space. Each voxel in the image can hold a number, a color, or intensity, which depends on the interaction between the light beam and the material in the corresponding region of space when using a single-wavelength light beam. Each voxel in the image may hold an array of numbers, spectrum with peaks and valleys, that depend of the interaction between the light beam and the material in the corresponding region of space when using a multiple-wavelength light beam. Each voxel in the image may hold several arrays of numbers (several spectra) that depend of the interaction between each light beam and the material in the corresponding region of space when using several multiple-wavelength light beams. Non-limiting examples of techniques to obtain the voxel representations can include laser confocal scanning microscopy, fluorescence microscopy, digital microscopy, spectral imaging, multispectral imaging, hyperspectral imaging, snapshot hyperspectral imaging, Raman spectrum, fluorescence spectrum, etc.

The method700proceeds to block704which provides for performing a segmentation of the tomography. That is, the optical tomography is analyzed by the computing device806to determine whether multiple classes are present in the sample where the class can correspond to the structural phases of matter. The multi-class segmentation algorithms that can be used based on the voxel representations. For example, if the image is acquired with a single wavelength, the color, intensity, and texture of the voxels, the segmentation algorithm that is used can include multi-threshold Otsu, K-means clustering, region-growing, artificial neural networks, watershed, etc. If the image was acquired with a single spectrum, the segmentation may be performed using known lookup tables for material spectra, machine-learning models trained using the lookup tables (hyperspectral watershed transformation, minimum spanning forest, etc.). If the image was acquired with multiple spectra (Raman, fluorescence, etc.), the segmentation may be performed using machine learning models trained on the known spectra for each material. In one or more embodiments of the invention, at block706if the distinct phases cannot be identified in the segmentation step by the computing device806, the tomography should be re-acquired as shown at block708with higher contrast by optimizing the choice of light beam wavelengths. In a different embodiment of the invention, other contrast agents (e.g., fluorescent particles) can be used to better distinguish the phases in the sample when obtaining the images using the measuring device802. The method700, at block710labels the tomography to identify a liquid phase, gas phase, and/or solid phase. It should be understood that both fluids F1and F2can exist in the liquid state. The method700proceeds to block712and the computing device806calculates the interfaces between each of the phases of the sample. For example, the F1-S interface, the F2-S interface, and the F1-F2interfaces are determined for the sample. The interface determination techniques can include adjusting a polygon surface mesh in 3D to a point cloud, adjusting a mode surface fit using a complete function basis set (e.g., Bessel functions), or any other suitable numerical interface identification algorithm including but not limited to marching cubes/tetrahedral, Canny filter, level-set method, etc.

At block714, the method700a surface mesh is applied to the tomography. In one or more embodiments of the invention, the surface mesh can include a polygon surface mesh which can be applied in 3D and may be adjusted to the point cloud. The intersection between each of the interfaces is located at block716. At decision block718, if it is determined that the intersection line is not closed, the mesh can be refined as shown in block720, and recalculates the interfaces and returns to block712.

At block722, the computing device806identifies a three-phase contact line in the tomography. Block724provides for calculating figures-of-merit (FOM) from the two-phase interfaces and three-phase contact line. The FOM includes but is not limited to the contact angle (F1-F2-S), the contact line (F1-F2-S), the contact area (F2-S), the interface area (F1-F2), the droplet shape (F2), the droplet curvature (F2), the droplet height (F2), the droplet radius (F2), the droplet volume (F2), etc. In one or more embodiments of the invention, the droplet contact angle (Block726) may be obtained by calculating the normal vectors of the F1-F2surface close to the contact line. The droplet volume (Block728) may be obtained by calculating the volume enclosed by the surfaces F1-F2and F1-S. The absorption energy (Block730) density may be obtained by including bulk, surface and line energy contributions. Finally, the data can be displayed on the computing device806or other display as shown at block732.

FIG. 8depicts an example system800including a computing device that is operably coupled to the microscope. The measuring device802, such as an optical microscope, is used to analyze the sample804which it loaded onto the measuring device802. The measuring device802is coupled to a computing device806. The computing device806can be implemented as discussed below with reference toFIG. 9. The measuring device802and computing device806are configured to communicate and exchange data to obtain a 3D representation of the sample. The data obtained from the measuring device802and the computing device806can be stored in the DB808.

Thus, as configured inFIG. 9, the system900includes processing capability in the form of processors101, storage capability including system memory114and mass storage104, input means such as keyboard109and mouse110, and output capability including speaker111and display115. In one embodiment, a portion of system memory114and mass storage104collectively store an operating system to coordinate the functions of the various components shown inFIG. 9.

The techniques described herein improve over the prior art by allowing the wettability characteristic to be determined for a three-phase system including fluid-fluid-solid systems, regardless of the relative densities of the two fluids. Using the techniques described herein allow for the wettability to be determined for a liquid-liquid-solid system, instead of being limited to a liquid-gas-solid system. In addition, the techniques described herein allow not only obtaining the droplet silhouette, but also obtain the 3D droplet topography and the three-phase contact line simultaneously. The techniques using optical microscopy collect data in each voxel. Thus, if the spectroscopy is performed at a range of wavelengths (such as infra-red, Raman, UV-Vis), then it is possible to identify if there are contaminants into F1of F2or over the surface S which could change the wettability.

The technical benefits and effects include a device that performs optical tomography (3D imaging) and a method that extracts accurate droplet shapes and three-phase contact geometry from the tomography to determine wetting properties of fluid-fluid-solid systems as disclosed herein.