Cryogenic Tube Picking Compartment with Thermal Stratification
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Solution Overview
Problem
Conventional tube picking mechanisms are unreliable and inefficient in ultra-low temperature or cryogenic environments due to electrical, pneumatic, and hydraulic component failures, thermal expansion issues, and frost/ice formation, which can contaminate and jam mechanical parts, and expose samples to undesirable warming when trying to retrieve tubes from storage racks.
Innovation Solution
A tube picking mechanism with a dual compartment design, where the lower compartment is maintained at ultra-low or cryogenic temperatures for tube picking and the upper compartment houses active mechanical and electrical components at a warmer temperature, utilizing thermal stratification to maintain the cold environment and prevent moisture ingress, with a picker head and presenter push pin system for precise tube handling and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a tube picking mechanism operates in an ultra-low temperature or cryogenic environment, then sample warming is minimized, but electrical, pneumatic, and hydraulic components become unreliable and mechanical parts jam due to frost and ice formation
Solution Approach 1:
The system is divided into two distinct compartments: a cold compartment maintained at ultra-low or cryogenic temperatures for storing sample racks, and a warm compartment housing all electrical, pneumatic, and hydraulic components at temperatures above -50°C. This segmentation allows each compartment to be optimized for its specific function without compromising the other, resolving the contradiction between maintaining low storage temperature and ensuring component reliability
Solution Approach 2:
A transfer mechanism acts as an intermediary between the cold and warm compartments, enabling tube picking operations to occur in the cold environment while mechanical components remain in the warm environment. The transfer mechanism includes a picker head with gripping fingers that can operate in the cold compartment, while being driven by motors and actuators located in the warm compartment, thus mediating between the conflicting temperature requirements
2Reliability
If the tube picking mechanism is placed in a warmer environment (e.g., -20°C) to ensure component reliability, then electrical and mechanical components operate reliably, but samples experience undesirable warming
Solution Approach 1:
The system separates the operating environment for samples from the operating environment for components by creating distinct cold and warm compartments. The cold compartment maintains ultra-low or cryogenic temperatures for sample storage, while the warm compartment maintains temperatures above -50°C for reliable component operation, eliminating the need to compromise sample temperature for component reliability
Solution Approach 2:
The transfer mechanism serves as an intermediary that enables tube picking to occur in the cold compartment without requiring the entire system to be warmed. The picker head operates in the cold environment to minimize sample warming, while being controlled by components in the warm environment, thus mediating between the conflicting temperature requirements
3Temperature
If conventional tube picking mechanisms operate in ultra-low temperature environments, then sample storage conditions are maintained, but frost and ice formation contaminates and jams mechanical parts
Solution Approach 1:
The harmful moisture that causes frost and ice formation is extracted from the cold compartment by introducing a vapor barrier that prevents moisture-laden air from entering. The warm compartment acts as a barrier that blocks moisture from reaching the cold compartment, thereby taking out the source of the harmful frost and ice formation from the ultra-low temperature environment
Solution Approach 2:
The vapor barrier and warm compartment act as intermediaries that prevent moisture from reaching the cold compartment where tube picking occurs. This intermediary barrier eliminates the condition that leads to frost and ice formation on mechanical parts, while still allowing the cold compartment to maintain its ultra-low or cryogenic storage temperature
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 reliable and efficient picking and transfer of tubes within ultra-low or cryogenic storage systems, minimizing sample warming and mechanical failures, while maintaining the cold environment through strategic compartment temperature differences and insulation.
Implementation Method 1
utilizing thermal stratification to maintain the cold environment
Implementation Method 2
maintaining the cold environment through strategic compartment temperature differences and insulation
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
A tube picking mechanism is designed for use in an automated, ultra-low temperature (e.g. -80°C or -135°C) or cryogenic (e.g., about -140°C to -196°C) storage and retrieval system that stores biological or chemical samples. The samples are contained in storage tubes held in SBS footprint storage racks that are normally stored within an ultra-low temperature or cryogenic freezer compartment. The tube picking mechanism includes a tube picking chamber that is maintained at about -80°C, about -135°C or at cryogenic temperatures in cryogenic applications. Active electrical and mechanical components are maintained in a compartment above and separate from the refrigerated, ultra-low temperature or cryogenic compartment. Thermal stratification inhibits heat transfer into the lower, ultra- low temperature or cryogenic compartment in which tube picking occurs from the upper compartment in which active electrical and mechanical components are located, and also inhibits heat transfer into the lower, ultra-low temperature or cryogenic compartment via an access door for tube storage racks.