High-Index Immersion Optics for Sub-Micrometer IMS Resolution
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Solution Overview
Problem
Current imaging mass cytometry (IMC) technologies face challenges in achieving sub-micrometer resolution and maintaining a sufficient signal-to-noise ratio, primarily due to limitations in confining the sampling spot area to 200 nm or less and ensuring adequate analyte signal production.
Innovation Solution
The use of high refractive index immersion lenses to focus laser radiation tightly, combined with electron microscopy for refining image resolution, and charged particle bombardment techniques to enhance sampling precision, along with labelling methods for specific analysis of biological samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional lenses are used to focus laser radiation, then the sampling spot area can be reduced, but the lateral resolution is limited and cannot achieve sub-micrometer scales
Solution Approach 1:
The patent changes the refractive index parameter of the lens material from conventional values to high refractive index materials (such as diamond with n≈2.4, or other materials with n>1.7). This parameter change enables the lens to focus laser radiation to a spot size of 200 nm or less, achieving sub-micrometer lateral resolution while maintaining a relatively simple optical system configuration
Solution Approach 2:
The patent employs composite optical systems that combine high refractive index lens materials with specific geometric configurations. The use of diamond or other high-index materials in conjunction with precisely engineered lens shapes creates a composite optical solution that achieves superior resolution without requiring complex multi-element lens assemblies
2Measurement precision
If the sampling spot area is confined to 200 nm or less to improve resolution, then lateral resolution improves, but the amount of analyte in the ablated material decreases leading to insufficient signal-to-noise ratio
Solution Approach 1:
The patent changes multiple parameters simultaneously: using high refractive index lenses to reduce spot size to 200 nm or less for improved resolution, while also adjusting laser pulse energy and duration parameters to ensure sufficient ablation depth and analyte release. This coordinated parameter optimization maintains signal-to-noise ratio despite the reduced sampling area
Solution Approach 2:
The patent transitions from two-dimensional surface ablation to three-dimensional volume ablation by optimizing the laser pulse parameters and focal depth. This allows the confined sampling spot to access analyte from a larger three-dimensional volume beneath the surface, ensuring sufficient signal generation while maintaining sub-micrometer lateral resolution
3Measurement precision
If immersion lenses with high refractive index are used to focus laser radiation tightly, then lateral resolution improves, but the depth resolution and focal precision become challenging to control
Solution Approach 1:
The patent changes the lens material parameter to high refractive index materials, which inherently provide a shorter depth of field and tighter focal confinement. This parameter change improves both lateral resolution and depth discrimination, allowing precise control of the focal volume for ablation
Solution Approach 2:
The patent implements feedback control mechanisms that monitor the ablation process in real-time and adjust laser parameters to maintain precise focal positioning. This feedback system compensates for variations in sample thickness and lens positioning, ensuring consistent focal precision despite the high numerical aperture of the immersion lenses
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
These approaches enable high-resolution imaging at sub-micrometer scales, improving lateral and depth resolution, and allowing for detailed analysis of biological samples with increased precision and specificity.
Implementation Method 1
lenses which maintain a particularly high refractive index around the ablation spot (e.g. immersion lenses), which focus the laser used for laser ablation down to a particularly small ablation spot
Implementation Method 2
LA-ICP-MS (a form of IMS in which the sample is ablated by a laser)
Implementation Method 3
the ablated material is then ionised in an inductively coupled plasma before the ions are detected by mass spectrometry
Data Source
AI summary
The present invention relates to the high resolution imaging of samples using imaging mass spectrometry (IMS) and to the imaging of biological samples by imaging mass cytometry (IMC™) in which labelling atoms are detected by IMS. LA-ICP-MS (a form of IMS in which the sample is ablated by a laser, the ablated material is then ionised in an inductively coupled plasma before the ions are detected by mass spectrometry) has been used for analysis of various substances, such as mineral analysis of geological samples, analysis of archaeological samples, and imaging of biological substances. However, traditional LA-ICP-MS systems and methods may not provide high resolution. Described herein are methods and systems for high resolution IMS and IMC.