Passive Cell Freezing Device with Ventilation-Assisted Thermal Equalization
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Solution Overview
Problem
Existing passive cell freezing systems face challenges in achieving uniform temperature reduction profiles for multiple vials, leading to variable freezing rates and increased thermal mass, which compromises cell viability and requires individual transfer to archival storage, increasing the risk of specimen warming.
Innovation Solution
An insulating chamber with gas inlet and outlet ports, a removable rack that divides the chamber into upper and lower compartments, and a gaseous pathway facilitated by thermodynamic principles to equalize thermal energy loss across vials, allowing simultaneous transfer of vials to archival storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple vials are densely packed in a passive freezing system, then the sample capacity is increased, but the thermal mass increases and thermal energy distribution becomes uneven, resulting in variable freezing rates
Solution Approach 1:
The freezing chamber is segmented into multiple zones with independent temperature control capabilities. Each zone can be optimized for specific freezing rates, allowing dense packing of vials while maintaining uniform freezing across different regions. The chamber includes multiple cooling sources distributed throughout to ensure even thermal energy distribution.
Solution Approach 2:
A thermal management medium (such as isopropyl alcohol or other heat transfer fluid) is introduced into the chamber to act as an intermediary that distributes thermal energy uniformly among all vials. This medium circulates through channels positioned between vials, ensuring consistent heat transfer and eliminating thermal gradients that occur with direct air cooling.
2Quantity of substance
If the number of vials in the cluster is increased, then the sample capacity is increased, but a greater quantity of thermal energy must be released per unit time, necessitating a reduction in insulation thickness, which worsens the imbalance in freezing rates
Solution Approach 1:
A fluid circulation system using isopropyl alcohol or similar heat transfer fluid is implemented to actively manage thermal energy distribution. The fluid circulates through a network of channels positioned between and around vials, providing controlled heat transfer that scales with the number of vials without requiring changes to insulation thickness. This hydraulic/ pneumatic system enables uniform cooling across large numbers of vials.
Solution Approach 2:
The system dynamically adjusts thermal parameters including fluid flow rate, fluid temperature, and channel configuration based on the number of vials present. Sensors monitor temperature distribution and automatically modify cooling parameters to maintain optimal freezing rates regardless of sample capacity, allowing the system to adapt to varying numbers of vials without compromising freezing uniformity.
3Reliability
If vials are transferred individually to archival storage, then the freezing process can be completed, but the process is time-consuming and increases the risk of specimen warming
Solution Approach 1:
The freezing chamber is designed with integrated archival storage capability, allowing vials to be transferred en masse rather than individually. The chamber includes a removable tray or carriage that can hold multiple vials and be extracted as a single unit and placed directly into archival storage. This merging of freezing and storage functions eliminates repeated openings of the chamber and reduces total transfer time while maintaining cell viability through continuous temperature control.
Solution Approach 2:
The system pre-cools the archival storage chamber or pre-prepares transfer trays before the freezing cycle is complete. This preliminary action ensures that when vials are transferred in bulk, they immediately enter an appropriate storage environment without temperature shock or warming, maintaining cell viability while minimizing transfer time and manual handling.
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 solution ensures uniform freezing rates across vials, maintaining cell viability and eliminating the need for individual transfer, thereby reducing the risk of warming and enhancing the efficiency of the freezing process.
Implementation Method 1
a gaseous pathway facilitated by thermodynamic principles to equalize thermal energy loss across vials
Implementation Method 2
An insulating chamber that surrounds a cluster of sample vials and their contents. In some embodiments, the chamber is constructed from an insulating material such as polyethylene, styrene, or urethane foam.
Implementation Method 3
a gas (typically air) may enter the lower chamber via the one or more ports and pass into the upper chamber via gas vents provided in the removable rack
Data Source
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AI summary
A sample freezing device (500) comprising: a base container (535) having a top end, a bottom end, and a lower chamber extending therebetween, the top end having an opening and the bottom end having an inlet port (540); a cover (510) having a top end, a bottom end, and an upper chamber extending therebetween , the top end having an outlet port (505) and the bottom end having an opening, the bottom end being configured to interconnect with the top end of the base container; and a sample rack (520) disposed between the base and the cover, wherein the sample rack divides the lower chamber from the upper chamber when the cover is interconnected with the base container.