Supercritical Fluid Cooling for Ice Crystal-Free Biological Samples
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Solution Overview
Problem
Conventional methods for controlling the temperature of biological samples with abrupt temperature settings are limited by slow cooling rates, contamination, and limited controllability, making it difficult to achieve ice crystal-free freezing and thawing, especially for biological samples, which can result in cell damage and hinder the observation of dynamic processes.
Innovation Solution
A method and device that utilize a supercritical temperature control medium, fed to the rear side of a carrier substrate at high pressure, allowing for rapid and controlled temperature changes without forming insulating vapor layers, enabling ice crystal-free freezing and thawing by maintaining the cooling medium in a supercritical state until it contacts the substrate, thereby enhancing heat transfer and preventing phase boundary formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional cooling methods (liquid nitrogen spraying, nozzle cooling) are used to achieve rapid cooling, then cooling rate is improved, but sample contamination and limited controllability worsen
Solution Approach 1:
A carrier substrate is introduced as an intermediary between the cooling medium and the sample. The substrate receives the cooling medium on its rear side and conducts the cooling effect to the sample on its front side, preventing direct contact between the cooling medium and the sample, thus avoiding contamination while maintaining rapid cooling rates
Solution Approach 2:
The cooling system is segmented into distinct functional zones: a carrier substrate that holds the sample, a cooling medium supply system, and a heat conduction interface. This segmentation allows independent optimization of each component - the substrate can be made contamination-resistant while the cooling medium can be aggressively applied
2Power
If liquid gas is sprayed onto a warm surface, then cooling capacity is improved, but Leidenfrost phenomenon forms an insulating vapor layer reducing heat conduction
Solution Approach 1:
The carrier substrate is pre-cooled to a temperature below the freezing point of water before the cooling medium is applied. This preliminary cooling prevents the formation of the Leidenfrost vapor layer by ensuring the surface temperature is already in the range where direct contact cooling occurs, thereby maintaining high heat conduction efficiency
Solution Approach 2:
The temperature parameter of the carrier substrate is changed and maintained below the freezing point of water. This parameter change fundamentally alters the thermal interaction between the cooling medium and substrate, eliminating the Leidenfrost effect and enabling efficient heat transfer
3Quantity of substance
If gaseous cooling medium is used, then heat capacity is improved, but lower density results in insufficient cooling capacity
Solution Approach 1:
The state parameters of the cooling medium are changed by applying high pressure, transforming it from a gaseous state with low density to a supercritical fluid state with high density. This parameter change simultaneously increases both the heat capacity and the cooling capacity, resolving the contradiction between these two properties
4Power
If high pressure is applied to achieve supercritical state, then heat transfer is improved, but device complexity increases
Solution Approach 1:
The carrier substrate serves multiple functions: it holds the sample, conducts cooling from the rear side to the front side, and provides a surface for the cooling medium to contact. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in device complexity despite the high pressure requirements
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 approach allows for the fixation and observation of short-lived states at high resolution, achieving cooling or heating rates exceeding 5,000 K/s, preventing ice crystal formation, and allowing for the gentle heating of biological samples without additives or excessive pressure, thus preserving the sample's integrity.
Implementation Method 1
a temperature control medium is fed to the carrier substrate in the supercritical state... causing the temperature of the sample to change abruptly
Implementation Method 2
maintaining the cooling medium in a supercritical state until it contacts the substrate, thereby enhancing heat transfer and preventing phase boundary formation
Implementation Method 3
the water does not form ice crystals but solidifies amorphously or like glass (vitrification)... achieving cooling or heating rates exceeding 5,000 K/s, preventing ice crystal formation
Data Source
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AI summary
The invention relates to the temperature control, in particular to the ice crystal-free freezing or thawing of a sample (1), comprising the steps of providing the sample (1) on a front side (11) of a carrier substrate (10) and supplying a temperature-control medium (2) to a back side (12) of the carrier substrate (10), wherein the temperature-control medium (2) in the above-critical state and having a pressure that is higher than the atmospheric pressure is brought into contact with the back side (12) of the carrier substrate (10) and the temperature of the sample (1) is rapidly modified. The invention further relates to a temperature control device (100) for the temperature control of a sample.