Surface Charge Measurement via Electro-Optical Scattering
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Solution Overview
Problem
Existing surface charge measurement systems, particularly those using capillary cells, are inconvenient and not straightforward for sample preparation, and they often require specialized instruments for determining surface zeta potential or charge properties.
Innovation Solution
A system comprising a sample holder with opposed electrodes, a measurement chamber filled with liquid electrolyte, and a laser light source for directing a light beam parallel to the sample surface, allowing detection of scattered light over a range of distances, which enables accurate and repeatable measurements of surface charge using tracer particles and electro-osmotic flow analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capillary flow measurement methods are used to determine surface charge, then measurement capability is achieved, but sample preparation becomes complex and inconvenient
Solution Approach 1:
The patent replaces traditional mechanical capillary flow measurement systems with an electro-optical measurement system. Instead of using capillary tubes requiring precise mechanical assembly and specialized sample preparation, the invention uses a planar electrode configuration with laser light scattering detection to measure electro-osmotic flow, thereby simplifying sample preparation while maintaining measurement capability
Solution Approach 2:
The measurement system is designed to accommodate multiple sample types and geometries through a universal planar electrode configuration. The flat electrode design allows various samples (liquids, suspensions, gels) to be placed directly on the electrode surface without requiring specialized capillary tubes or complex sample formatting, making the system universally applicable
2Measurement precision
If specialized instruments are used for surface charge measurement, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the measurement functions into a single integrated planar electrode device that integrates sample placement, electric field application, and light scattering detection in one compact unit. This merging eliminates the need for multiple specialized instruments and complex sample transfer procedures, reducing overall device complexity while maintaining measurement accuracy
Solution Approach 2:
The invention uses light scattering detection to create an optical copy or signal representation of the electro-osmotic flow movement. By detecting scattered light from tracer particles rather than directly measuring fluid flow mechanically, the system achieves accurate surface charge measurement without requiring complex mechanical measurement instruments
3Measurement precision
If traditional measurement methods are used, then surface charge data can be obtained, but measurement time and preparation effort increase
Solution Approach 1:
The planar electrode configuration is pre-configured with the electric field geometry and detection optics aligned before sample introduction. Tracer particles are pre-dispersed in the sample, eliminating the need for complex in-situ preparation steps during measurement, thereby reducing measurement time while maintaining data quality
Solution Approach 2:
The invention replaces time-consuming mechanical capillary flow measurement with rapid electro-optical detection. The laser light scattering method provides real-time detection of electro-osmotic flow velocity, significantly reducing measurement time compared to traditional methods that require gradual capillary filling and sequential measurements
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
This approach allows for quicker, more convenient, and accurate measurement of surface charge and zeta potential, improving upon existing methods by enabling measurements on easily prepared sample geometries and providing reproducible results in agreement with literature values.
Implementation Method 1
a laser light source positioned and configured to direct a light beam through the measurement chamber between the electrodes and parallel to the planar surface of the sample when the sample holder is received in the measurement chamber; and a detector positioned and configured to detect scattered light from the measurement volume
Implementation Method 2
Exemplary embodiments include methods and apparatus for determining a surface zeta potential by electro-osmotic flow measurement in a dip cell arrangement
Data Source
AI summary
The invention relates to methods and apparatus for determining properties of a surface. Embodiments disclosed include an apparatus for measuring a surface charge of a sample, comprising: a sample holder having an opposed pair of electrodes and configured to hold a sample in position in a measurement volume between the electrodes such that a planar surface of the sample is aligned orthogonal to the electrode surfaces; a measurement chamber for containing a measurement liquid and having an open end configured to receive the sample holder to position the electrodes in a preset orientation; a laser light source positioned and configured to direct a laser beam through the measurement chamber between the electrodes and parallel to the planar surface of the sample when the sample holder is received in the measurement chamber; and a detector positioned and configured to detect scattered light from the measurement volume, wherein the apparatus is configured to allow for detection of the scattered light by the detector over a range of distances from the surface of the sample.