IScat Microscopy Motion Correction via Ratiometric Signatures
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Solution Overview
Problem
Existing interferometric scattering microscopy (IScat) techniques face limitations in detecting small objects due to sample motion causing erroneous signals, which conventional motion correction methods like iterative image registration and Fourier transforms cannot accurately address in real time.
Innovation Solution
A method to correct for sample motion by estimating a ratiometric motion signature and subtracting it from the signal, allowing real-time processing at kHz rates, and using a spatial filter to enhance contrast for weak scatterers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional motion correction methods (iterative image registration, Fourier transforms) are used, then measurement precision can be improved, but device complexity increases and real-time processing at kHz rates becomes unachievable
Solution Approach 1:
The patent extracts the motion correction function from complex image processing algorithms and implements it through a dedicated motion detection module that operates independently from the main imaging pipeline. This allows motion correction to be performed as a separate, optimized process that can run at kHz rates without interfering with the core imaging functions.
Solution Approach 2:
The patent replaces conventional computational image registration methods with a direct signal processing approach that detects motion signatures in the interferometric scattering signal itself. This substitution of the correction mechanism enables real-time processing by working directly with the optical signal rather than processing complete images through complex algorithms.
2Measurement precision
If high sensitivity detection is used to detect single molecules, then measurement precision improves, but sample motion creates erroneous signals that drown out particle signals
Solution Approach 1:
The patent converts the harmful effect of sample motion into a detectable signal feature. By detecting the motion signature in the interferometric scattering pattern, the system can distinguish between signal changes caused by particle binding and those caused by sample motion, thereby eliminating motion artifacts from the measurement.
Solution Approach 2:
The patent implements a feedback mechanism where the detected motion signature is used to correct the measurement signal. The motion detection module continuously monitors for motion artifacts and provides feedback to correct the imaging data in real-time, maintaining high detection sensitivity while eliminating motion-induced errors.
3Measurement precision
If ratiometric contrast imaging is used to detect particle binding, then detection sensitivity improves, but sub-pixel sample motion creates signals of the same amplitude as single proteins
Solution Approach 1:
The patent introduces an intermediary motion detection and correction module between the imaging system and the analysis system. This intermediary detects motion signatures from the interferometric scattering signal and corrects the data before it reaches the analysis pipeline, preventing motion artifacts from being misinterpreted as biological signals.
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 precise detection and correction of sample motion, enhancing image clarity and accuracy for small objects like proteins and nanoparticles, while maintaining high sensitivity and reducing noise from sample movement.
Implementation Method 1
the spatial filter being arranged to pass output light but with a reduction in intensity that is greater within a predetermined numerical aperture
Implementation Method 2
illuminating a sample with at least one light source... such that output light is formed; the output light comprising both illuminating light reflected from the sample location and light scattered from the sample location
Data Source
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AI summary
A method of imaging a sample by interferometric scattering microscopy, the method comprising illuminating a sample with at least one light source, the sample being held at a sample location comprising a reflective surface, such that a reflected signal is formed; the reflected signal comprising light from the light source and light scattered by the sample; detecting the output light over a first time window for a first frame N1; detecting the output light over a second time window for a second frame N2; calculating a ratiometric signal R which is the ratio of N1 and N2 minus 1; estimating the ratiometric motion signature S = (Sx, Sy) from frames N1 and N2 with S defined as the ratiometric image which would be measured from an invariant sample moving along x and y for a given motion vector m = (mx, my); estimating m as the most consistent vector such that R is approximated using S and m; calculating the corrected ratiometric contrast image R* from R, S and m.