Scanning Electron Microscopy of Floating Micro Samples
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Solution Overview
Problem
Conventional techniques fail to effectively observe micro samples floating on a liquid surface using electron microscopy due to issues like evaporation of aqueous solutions, sample aggregation, and charging problems, and existing methods using ionic liquids either bury the sample or require complex sample holder movements.
Innovation Solution
A method involving a hydrophobic or hydrophilic ionic liquid aqueous solution of low viscosity is used to float micro samples, allowing them to aggregate and align freely, with controlled orientation, and then dried to reduce flowability for stable scanning electron microscope observation without covering the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid is used for electron microscope observation, then the micro sample can float and be observed in its natural state, but the liquid evaporates in the vacuum environment
Solution Approach 1:
The patent uses cryo-freezing to transition the liquid from liquid phase to solid phase, allowing it to maintain its sample-floating function without evaporating in the vacuum environment. The frozen liquid preserves the sample's natural state while being compatible with electron microscope observation.
Solution Approach 2:
The patent introduces a specialized cryo-stage as an intermediary device between the sample and the electron microscope environment. This cryo-stage maintains the liquid in a frozen state, mediating between the requirement for liquid-based sample floating and the vacuum environment that would otherwise cause evaporation.
2Loss of substance
If the liquid is frozen to prevent evaporation, then the liquid does not evaporate in vacuum, but the freezing changes the shape and form of the micro sample
Solution Approach 1:
The patent carefully controls the freezing parameters (temperature, freezing rate) to minimize shape changes. By optimizing these parameters, the liquid is frozen in a way that preserves the original shape and form of the micro sample as much as possible while still preventing evaporation.
Solution Approach 2:
The patent performs preliminary optimization of freezing conditions before actual sample observation. This preliminary action involves adjusting freezing parameters to find the optimal balance between preventing evaporation and maintaining sample shape integrity.
3Loss of substance
If oil is used as liquid material, then the liquid does not evaporate in vacuum, but the sample undergoes rapid flowing movement under electron beam irradiation
Solution Approach 1:
The patent uses a cryo-stage as an intermediary that holds the liquid in a frozen state, preventing the rapid flowing movement that occurs with oil under electron beam irradiation. The frozen liquid provides both evaporation prevention and positional stability.
Solution Approach 2:
The patent replaces the mechanical/chemical approach of using oil (which relies on viscosity to prevent evaporation) with a physical phase-change approach (freezing). This substitution eliminates the flowing movement problem while maintaining evaporation prevention.
4Object-generated harmful factors
If ionic liquid is applied to sample surface, then charging problem is solved, but the original fine structure of the sample is buried in the ionic liquid
Solution Approach 1:
The patent extracts the charging problem solution from the ionic liquid application method. Instead of applying ionic liquid to the sample surface, the patent uses a frozen liquid approach that inherently prevents charging while preserving sample structure, effectively taking out the harmful effect of ionic liquid burial.
Solution Approach 2:
The patent uses a frozen liquid as an intermediary between the sample and the electron beam environment. This intermediary prevents charging problems without burying the sample structure, unlike direct ionic liquid application.
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 natural observation of micro sample aggregation, dispersion, and orientation on a liquid surface, preventing ionic liquid adherence and allowing precise control of sample direction for effective electron microscopy of various materials, including biological and functional substances.
Implementation Method 1
a floating or hydrophobic sample is floated on a surface of a hydrophilic ionic liquid aqueous solution
Implementation Method 2
A floating or hydrophobic sample is floated on a surface of a hydrophilic ionic liquid aqueous solution to prevent the micro sample from being covered with the ionic liquid
Implementation Method 3
the ionic liquid aqueous solution is dried to lower the flowability of the ionic liquid aqueous solution, after the form of the micro sample has stabilized
Implementation Method 4
scanning electron microscope observation
Data Source
AI summary
A micro sample floating on the surface of an ionic liquid is observed by scanning electron microscopy without the sample being covered with the ionic liquid. A floating or hydrophobic sample is floated on the surface of a hydrophilic ionic liquid aqueous solution to prevent the micro sample from being covered with the ionic liquid. A hydrophobic ionic liquid is used for hydrophilic samples. With the use of an ionic liquid aqueous solution of low viscosity and large flowability, the micro sample is allowed to freely aggregate, disperse, and align on the surface of the ionic liquid, and to refloat even when settled in the ionic liquid. For easy observation with a scanning electron microscope, the ionic liquid aqueous solution is dried to lower the flowability of the ionic liquid aqueous solution, after the form of the micro sample has stabilized and before electron microscope observation.