Dark Field Microscopy Volume Calibration for Nanoparticle Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for measuring nanoparticle properties in poly-disperse samples are inaccurate due to non-uniform light intensity in dark field microscopy, leading to errors in particle size distribution and concentration, as smaller particles' signals are often undetected or obscured by larger particles, and fail to account for growth or dissolution rates.
Innovation Solution
A method to calibrate the investigated volume by determining the relationship between scattered light intensity, particle size, and relative refractive index, allowing for a four-dimensional relationship between light source wavelength, scattered light intensity, particle size, and investigated volume, enabling accurate particle size distribution calculation in unknown samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dark field microscopy is used to detect nanoparticles, then scattered light from particles can be observed, but the non-uniform light intensity causes smaller particles' signals to be undetected or obscured by larger particles
Solution Approach 1:
The patent applies parameter changes by systematically varying light source wavelengths and measuring scattered light intensity at multiple wavelengths. This multi-wavelength approach transforms the measurement parameters to capture the full scattering profile of particles across different sizes, enabling accurate differentiation between small and large particles that would otherwise be obscured in single-wavelength measurements.
Solution Approach 2:
The patent introduces an additional dimension by adding wavelength as a fourth parameter to the measurement space (transforming from 3D space-time to 4D space-space-time). This dimensional expansion allows the system to resolve particle size distribution more accurately by utilizing spectral information, effectively separating signals from particles of different sizes that overlap in conventional single-wavelength measurements.
2Quantity of substance
If conventional ensemble measurement methods are used, then measurements on large numbers of nanoparticles can be performed, but the light scattered from all particles cannot be resolved into constituent sizes
Solution Approach 1:
The patent applies segmentation by tracking and analyzing individual particles separately rather than measuring ensemble-averaged signals. Each particle's scattering trajectory and intensity profile are recorded and analyzed independently, allowing the system to resolve constituent sizes within the poly-disperse sample while maintaining measurements on large numbers of particles.
Solution Approach 2:
The patent applies preliminary action by pre-calculating calibration curves that relate scattered light intensity at multiple wavelengths to particle size and refractive index. These calibration relationships are established before sample measurement, enabling the system to directly determine particle properties from measured scattering signals without complex real-time computations.
3Loss of time
If measurements are performed without accounting for growth or dissolution rates, then snap-shot size distribution can be obtained, but the concentration and size distribution become inaccurate over time
Solution Approach 1:
The patent applies feedback by implementing continuous tracking of individual particles over time, recording their scattering intensity and position at multiple time points. This temporal feedback allows the system to detect and quantify particle growth or dissolution events, enabling correction of size distribution measurements to account for dynamic changes occurring during the measurement process.
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 calibration method ensures precise determination of particle size distribution and concentration by accounting for varying light intensities and refractive indices, improving the accuracy of nanoparticle tracking analysis in dark field microscopy.
Implementation Method 1
The nanoparticles in the investigative volume 38 scatter light 40 that is directed through a focusing optical objective 45
Implementation Method 2
a light source 15 that produces light beam 20 that passes through cylindrical lens and an optical objective 25 that form a light sheet 30
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A method for calibrating dark field microcopy setup is disclosed. The method includes preparing a plurality of particle samples, each with a known concentration and particle size, the plurality having more than one particle size and, optionally, more than one refractive index and more than one diluent. For each sample in the plurality, the sample is measured in the setup and the scattered light intensity and number of particles is measured. From this data, a relationship between the scattered light intensity, particle size and calibrated investigated volume can be determined. The calibrated investigated volume is used to obtain the proper particle size distribution in a given diluent.