Conductive Sample Fixation for Charging-Free Electron Microscopy
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Solution Overview
Problem
Electron microscopy of biological samples is hindered by charging and sample damage due to electron beam interactions, leading to image artifacts and specimen loss.
Innovation Solution
A method involving contacting biological samples with a lithium salt-containing freeze substitution solution, followed by permeation with a polymerizable resin and curing to form a 3-dimensional conductive sample block, which addresses charging and sample damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If biological samples are imaged using electron microscopy, then high-resolution imaging is achieved, but charging artifacts and sample damage occur due to electron beam interactions
Solution Approach 1:
The patent applies preliminary action by treating the biological sample with a conductive solution containing lithium salts and polymerizable resin before electron microscopy imaging. This pre-treatment establishes electrical conductivity in the sample, preventing charging artifacts during beam irradiation, and simultaneously provides structural support to prevent sample damage while maintaining high-resolution imaging capability
Solution Approach 2:
The patent uses a conductive solution containing lithium salts and polymerizable resin as an intermediary substance between the electron beam and the biological sample. This intermediary layer absorbs excess electrons and distributes charge, preventing direct harmful interactions between the electron beam and the sample while allowing high-resolution imaging to proceed
2Measurement precision
If beam energy is increased to improve imaging quality, then resolution is enhanced, but sample damage increases due to heat generation
Solution Approach 1:
The conductive resin solution acts as a thermal intermediary that facilitates heat dissipation from the irradiated sample regions. The resin matrix and lithium salts conduct away generated heat, preventing localized overheating and sample damage while allowing higher beam energies to be used for improved resolution
3Object-affected harmful factors
If working distance is increased to reduce beam energy density, then sample damage is reduced, but resolution deteriorates due to larger spot size
Solution Approach 1:
The patent changes the electrical and thermal parameters of the sample by impregnating it with conductive lithium salt and resin. This parameter modification allows the sample to tolerate higher beam energy densities without damage, enabling shorter working distances and smaller spot sizes to achieve higher resolution while maintaining sample integrity
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
The method enhances imaging quality by reducing charging artifacts and sample damage, enabling high-resolution electron microscopy of biological samples.
Implementation Method 1
contacting the biological sample with a freeze substitution solution comprising a lithium salt under conditions effective to permit permeation of the lithium salt into the biological sample
Implementation Method 2
contacting the biological sample with a first polymerizable resin under conditions effective to permit permeation of the polymerizable resin into the biological sample
Implementation Method 3
heating the so-prepared biological sample to a temperature effective to cure the first polymerizable resin and the second polymerizable resin
Implementation Method 4
heating the so-prepared biological sample to a temperature effective to cure the first polymerizable resin and the second polymerizable resin
Data Source
AI summary
Disclosed are compositions and methods for the conductive fixation of organic material, including biological samples. The compositions and methods described herein can address the problems of charging and sample damage caused by electron beam-sample interactions within an electron microscope.