Cryogenic Sample Cooling Without the Cold Gas Layer
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Solution Overview
Problem
Current methods for cryopreservation of biological samples, such as proteins and cells, face challenges in achieving rapid cooling rates without damaging the samples, as they often result in ice crystal formation and require high concentrations of cryoprotective agents, which can cause osmotic shock and structural changes.
Innovation Solution
The method involves minimizing the thickness of the cold gas layer above cryogenic liquids or solids by blowing away the cold gas layer with a warm, dry gas stream, allowing for increased temperature gradients and faster cooling rates, thereby reducing the time and concentration of cryoprotectants needed for vitrification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cold gas layer forms above the cryogenic liquid surface, then the sample is protected from direct liquid contact, but the cooling rate is reduced due to thermal insulation
Solution Approach 1:
The patent removes the cold gas layer that forms above the cryogenic liquid surface by introducing a stream of warm, dry gas. This extraction eliminates the thermal insulation barrier, allowing direct heat transfer from the sample to the cryogenic liquid while maintaining sample protection through controlled gas flow dynamics.
Solution Approach 2:
The patent changes the temperature parameter of the gas stream by introducing warm, dry gas to displace the cold gas layer. This parameter change transforms the thermal environment above the liquid surface, creating a temperature gradient that enhances cooling rates while preventing sample damage through controlled thermal exposure.
2Reliability
If high concentrations of cryoprotective agents are used to prevent ice crystal formation, then sample protection is improved, but osmotic shock and structural changes occur
Solution Approach 1:
The patent converts the potentially harmful cold gas layer into a beneficial component by using warm, dry gas to remove it. This transformation allows the system to achieve rapid cooling without requiring high concentrations of cryoprotective agents, thereby preventing osmotic shock while still preventing ice crystal formation through controlled vitrification.
Solution Approach 2:
The patent substitutes the mechanical/chemical approach of using high concentrations of cryoprotective agents with a thermal approach using controlled gas flow and temperature gradients. This substitution achieves ice crystal prevention through rapid cooling and vitrification without the harmful osmotic effects of high cryoprotectant concentrations.
3Speed
If the cold gas layer thickness is reduced by warm gas flow, then cooling rate increases, but energy consumption increases
Solution Approach 1:
The patent applies partial action by using a controlled stream of warm, dry gas that is sufficient to remove the cold gas layer and enable rapid cooling, but not excessive enough to cause significant energy waste. The gas flow is optimized to achieve the minimum necessary action for layer removal while minimizing energy consumption.
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 significantly increases cooling rates to up to 100,000 K/s, reduces the required cryoprotectant concentration, and minimizes sample damage, achieving vitrification at atmospheric pressure with modest sample speeds, comparable to the highest reported cooling rates for small samples.
Implementation Method 1
blowing away the cold gas layer with a warm, dry gas stream
Implementation Method 2
allowing for increased temperature gradients and faster cooling rates
Implementation Method 3
rapid cooling of small biological samples to cryogenic temperatures
Implementation Method 4
achieving vitrification at atmospheric pressure
Data Source
AI summary
A method and devices for rapid cooling of small biological samples by plunging them in a cryogenic liquid, such as liquid nitrogen, or contacting them with a cryogenic metal surface, reduce or eliminate the cold gas layer that forms above the liquid cryogens or cryogenic surfaces, producing an abrupt transition from ambient (e.g., room) temperature to the cryogen temperature as the sample enters the liquid or contacts the surface. To reduce or eliminate the effects of the cold gas layer, a flow of warm dry gas can be directed along the plunge path, for example. By removing this cold gas layer, cooling times for a 10 micron sample (the size of single cells and the smallest protein crystals now used protein crystallography) will decrease to ˜0.001 s.