Single Chamber Critical Point Drying Fluid Control
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Solution Overview
Problem
The existing critical point drying processes for samples, particularly biological and MEMS, are inefficient due to high consumption of intermediate and transitional fluids and require manual handling, leading to lengthy process durations and potential sample damage.
Innovation Solution
A method and apparatus that perform dehydration and critical point drying in a single chamber, using a single chamber for the entire process, with fluid ratios measured to optimize fluid usage and reduce manual handling, employing intermediate and transitional fluids like ethanol and carbon dioxide, and utilizing sensors and controlled fluid circulation to enhance efficiency and minimize fluid consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If manual dehydration and critical point drying are performed in separate vessels with empirical fluid amounts, then sample dehydration is achieved, but intermediate and transitional fluid consumption is high and process duration is long
Solution Approach 1:
The patent combines dehydration and critical point drying operations into a single chamber, eliminating the need for separate vessels and manual sample transfer. The chamber serves multiple functions: holding the sample during dehydration with intermediate fluid, then performing critical point drying with transitional fluid. This integration reduces fluid consumption by avoiding contamination and loss during transfer, and shortens process duration by eliminating manual handling steps and rest periods between operations.
Solution Approach 2:
The patent employs sensors (optical, electrical, or mass-based) to monitor the ratio of intermediate fluid to transitional fluid in real-time. This feedback mechanism allows the system to automatically adjust fluid flow rates and timing, optimizing the dehydration and drying processes. By continuously monitoring fluid composition, the system determines precise endpoint conditions, eliminating the need for excessive fluid usage and extended rest periods that were previously required to ensure complete fluid replacement.
2Reliability
If large amounts of transitional fluid are flowed through the chamber with additional rest periods, then sufficient replacement of intermediate fluid is ensured, but transitional fluid consumption increases and process duration extends
Solution Approach 1:
The control unit receives signals from sensors that monitor the fluid composition ratio and uses this feedback to determine when intermediate fluid has been sufficiently replaced by transitional fluid. The system automatically adjusts the flow rate and timing of transitional fluid based on real-time measurements, ensuring complete fluid replacement without requiring excessive amounts of transitional fluid or extended rest periods. This closed-loop control optimizes both reliability and resource efficiency.
Solution Approach 2:
The patent dynamically changes operational parameters (fluid flow rate, pressure, temperature) based on the monitored fluid composition ratio. As the replacement process progresses and the ratio changes, the system adjusts these parameters to maintain optimal replacement efficiency. This allows for rapid and complete fluid replacement with minimized transitional fluid consumption, eliminating the need for fixed, conservative parameters that previously required large fluid volumes and long time periods.
3Ease of manufacture
If manual handling is used to transfer samples between vessels, then dehydration and drying can be performed, but handling errors increase and sample damage risk rises
Solution Approach 1:
The patent integrates multiple processing steps (dehydration, fluid replacement, critical point drying) into a single automated chamber system. The sample remains in the chamber throughout the entire process, eliminating manual transfer operations. The control unit automatically manages fluid delivery, heating, pressurization, and depressurization sequences, ensuring sample integrity while achieving full process automation. This eliminates handling errors and reduces the risk of sample damage associated with manual vessel transfers.
4Object-affected harmful factors
If the chamber is filled with large amounts of intermediate fluid to prevent surface drying, then sample protection is maintained, but intermediate fluid consumption increases
Solution Approach 1:
The sensor system monitors the fluid composition ratio in real-time, providing feedback that allows the control unit to optimize intermediate fluid volume and flow rate. By continuously measuring the ratio of intermediate to transitional fluid, the system can determine the precise amount of intermediate fluid needed to protect the sample surface while enabling efficient replacement. This eliminates the need to use excessive intermediate fluid as a conservative measure, reducing consumption while maintaining sample protection.
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 reduces the consumption of intermediate and transitional fluids, shortens the process duration, minimizes manual handling errors, and ensures high sample dryness integrity by using a single chamber for dehydration and critical point drying, while avoiding fluid overconsumption and sample damage.
Implementation Method 1
Critical point drying exploits the property that fluids exhibit a supercritical state if temperature and pressure are above the critical point, where no phase boundary between liquid and gas exists
Implementation Method 2
Transferring the supercritical transitional fluid to the gaseous state by slowly depressurising the chamber and letting the gas escape while heating to avoid recondensation
Implementation Method 3
Replacing the intermediate fluid in the chamber with the transitional fluid. Transferring the transitional fluid from liquid to supercritical state by heating and pressurising the chamber
Data Source
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AI summary
A method for dehydration and critical point drying of a sample (2) in a single chamber (1) is introduced, comprising the steps of (a) dehydrating the sample (2) by replacing water by an intermediate fluid (3), (b) replacing the intermediate fluid (3) by a transitional fluid (4), (c) pressurising the transitional fluid (4) to or beyond its critical pressure and/or heating the transitional fluid (4) to or beyond its critical temperature, and (d) in response to gradually releasing the pressure, letting the transitional fluid (4) gasify and escape from the sample (2). In step (a) and/or step (b), a ratio of the fluid to-be-replaced to the replacing fluid is measured and used to control a supply of the replacing fluid. The method reduces consumption of intermediate fluid (3) and/or transitional fluid (4), making the process more efficient in terms of duration and user interaction while ensuring a high degree of dryness and the integrity of the sample (2).