Contact Angle Measurement via Drop Surface Reflection
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Solution Overview
Problem
Existing methods for determining the contact angle between a sample surface and a drop are limited by the need for complete imaging of the drop, making it difficult to measure large or inaccessible drops, and suffer from low-contrast imaging due to the transparency of the drop, which complicates image analysis.
Innovation Solution
A method and device that use the reflection properties of the drop surface to image an object on the drop, allowing for measurement without complete drop capture, utilizing a camera and image analysis system to determine the contact angle based on the position and symmetry axis of the drop, even when the drop is not fully in the field of view, and employing light sources for improved contrast and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complete imaging method is used to capture the entire drop, then the contact angle can be determined with sufficient accuracy, but it becomes impossible or extremely difficult to measure large or inaccessible drops in cavities
Solution Approach 1:
The invention extracts only the necessary information for contact angle determination from the drop image. Instead of requiring complete drop imaging, the method identifies and processes only the contact line and contact angle region, which are the critical elements for measurement. This extraction approach enables measurement of large or inaccessible drops while maintaining accuracy.
Solution Approach 2:
The patent applies partial action by capturing only the portion of the drop that contains the contact line and contact angle information, rather than imaging the entire drop. The camera is positioned and focused to capture the contact region specifically, which is sufficient for contact angle determination but reduces the imaging requirements for large or hard-to-reach drops.
2Measurement precision
If reflected light illumination is used to image the drop, then the drop diameter can be determined, but the transparency of the drop causes low-contrast imaging that complicates image analysis
Solution Approach 1:
The invention utilizes the optical properties of the drop, specifically the reflection and refraction of light at the contact line, to create high-contrast features in the image. By analyzing the intensity distribution and optical patterns at the contact region rather than relying on overall drop transparency, the method achieves both accurate diameter determination and easy image analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable and stable measurement of contact angles for drops of various sizes and locations, including those in cavities, with enhanced contrast and accuracy, allowing for precise determination of surface energy without requiring the entire drop to be imaged.
Implementation Method 1
an object is imaged on the drop surface using the reflection properties of the surface of a drop
Data Source
Figure 1~2
Figure 3a~3c
AI summary
A method for determining the contact angle (ϕ) between a sample surface (3), a gaseous environment, and a droplet (5) positioned on the sample surface (3) is described. The droplet (5) has a curved surface (7), an axis of symmetry (ASy-ASy), and a defined volume (VT). In this method, an object is imaged onto the droplet surface (7) based on the reflective properties of the surface (7) of the droplet (5). The position of the object relative to the optical axis (AA) of an optical measuring system and the position of the object relative to the sample surface (3) are known, and the axis of symmetry (ASy-ASy) of the droplet (5) is located at or near the optical axis (AA). The distance between the image and the optical axis (AA) of the droplet (5) is measured. The radius of curvature of the droplet (5) is determined using the measured distance, and the contact angle is determined using the radius of curvature.