Cryogenic Reservoir Level Control Using a Thermal Probe
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Solution Overview
Problem
Cryo-microscopy systems face challenges in maintaining a constant cryogenic liquid flow to prevent temperature variations and contamination, leading to wave-like temperature behavior and potential devitrification of samples during the transfer and analysis of frozen samples.
Innovation Solution
A system comprising a reservoir with a thermally conductive probe extending from a lower position to above the maximum filling level, equipped with a temperature sensor to generate a signal for a controller that regulates the liquid flow, ensuring a constant filling level and minimizing the risk of contamination and devitrification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cryogenic pump delivers variable amounts of cryogenic liquid, then the system can adapt to changing conditions, but the filling level becomes unstable causing wave-like temperature behavior
Solution Approach 1:
The patent implements a feedback control system using a level sensor (L) that continuously monitors the filling level in the reservoir and provides signals to the controller (S). The controller adjusts the pump operation based on this feedback to maintain a constant filling level, thereby resolving the contradiction between adaptability and stability by using closed-loop control to regulate variable delivery conditions.
Solution Approach 2:
The system changes the operational parameters of the pump by controlling it to deliver only the required amount of cryogenic liquid needed to maintain the desired filling level, rather than delivering variable amounts. This parameter control approach stabilizes the filling level while still allowing the system to adapt to changing conditions through the feedback mechanism.
2Measurement precision
If temperature sensors detect temperature deviations very fast, then temperature monitoring precision is improved, but feedback control problems occur leading to wave-like temperature behavior
Solution Approach 1:
The patent uses feedback control where the temperature sensor signals are fed back to the controller, which then adjusts the cryogenic liquid delivery accordingly. The fast temperature detection is managed through proper feedback control tuning to prevent oscillations, converting the high measurement precision into reliable control action.
Solution Approach 2:
The system employs periodic control action through the feedback loop that continuously monitors temperature and makes periodic adjustments to the cryogenic liquid delivery. This periodic action smooths out the fast temperature variations detected by the sensor, preventing wave-like behavior while maintaining accurate temperature control.
3Productivity
If the filling level of cryogenic liquid fluctuates, then the system responds to varying demands, but temperature variations and devitrification of samples occur
Solution Approach 1:
The feedback control system continuously monitors both the filling level (via level sensor L) and temperature (via temperature sensor T), and adjusts the pump operation to maintain constant filling level and temperature. This ensures sample integrity is maintained while still allowing the system to respond to varying demands through controlled adjustments.
Solution Approach 2:
The system maintains a constant filling level as a buffer or cushion against temperature variations that could cause devitrification. By keeping the filling level stable through feedback control, the system preemptively prevents temperature fluctuations that would threaten sample integrity, rather than reacting after problems occur.
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 system maintains a constant temperature at the sample location, reducing the risk of devitrification and contamination, and ensuring accurate temperature control for cryo-microscopy applications.
Implementation Method 1
a probe (120) comprising a probe body (122), in particular a thermally conductive probe body (122)
Data Source
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AI summary
The present inventive concept relates to a system (100) for controlling a filling level (X) of a reservoir (110) filled with a liquid, said system (100) comprising the reservoir (110) configured to be filled with liquid at least up to a maximum filling level (Xmax), a probe (120) including a probe body (122), at least a section of said probe body (122) extending, in a height dimension of the reservoir (110), from a first position (126) to a second position (124), the first position (126) being lower than the second position (124), and the second position (124) being above the maximum filling level (Xmax), and further including a temperature dependent sensor (128) configured to generate a signal based on a temperature at the second position (124), the temperature depending on the filling level (X), and a controller (250) for controlling the filling level (X) of the reservoir (110) depending on the sensor signal such that the filling level (X) is kept constant.