Self-Sealing Microreactor Using Meltable Wax Layer
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Solution Overview
Problem
Lab-On-Chip systems face issues with fluid loss due to evaporation during thermal cycles, which can alter reaction results, and existing sealing methods are either ineffective or complex and costly, with manual addition of mineral oil posing contamination risks.
Innovation Solution
A self-sealing microreactor using a meltable portion with cavities that melts to accommodate thermal expansion, preventing pressure increases and re-solidifies to seal the chamber, ensuring containment and preventing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a rigid cap is applied to seal the chip after filling with sample, then evaporation is prevented, but pressure dramatically increases on heating which may affect the reaction or break the cap or chip
Solution Approach 1:
The patent uses a sealing layer made of wax or other meltable material that transitions from solid to liquid phase during thermal cycling. This phase transition allows the sealing layer to accommodate pressure changes by becoming more compliant in liquid form, preventing cap or chip breakage while still preventing evaporation when solid.
Solution Approach 2:
The sealing material's physical properties change with temperature - it is solid at room temperature to prevent evaporation, but melts at elevated temperatures to accommodate pressure expansion. This dynamic parameter change resolves the contradiction between sealing effectiveness and pressure tolerance.
2Stress or pressure
If integrated membrane valves or bonded elastic caps are used to cope with pressure increases, then pressure tolerance is improved, but manufacturing and use become more complex and costly
Solution Approach 1:
Instead of complex mechanical pressure-regulating components, the patent uses a simple wax layer that passively regulates pressure through phase transition. This eliminates the need for intricate membrane valves or elastic cap mechanisms, significantly simplifying manufacturing while maintaining pressure tolerance.
Solution Approach 2:
The sealing wax layer is a simple, inexpensive material that can be easily integrated into disposable cartridges. This approach trades the reusability of complex pressure-regulating components for the simplicity and low cost of a single-use sealing layer that performs the same function.
3Object-affected harmful factors
If mineral oil layer is added manually on top of the sample, then evaporation is prevented and thermal expansion is accommodated, but sample contamination risk increases
Solution Approach 1:
The sealing wax layer is pre-integrated into the cartridge structure, eliminating the need for manual addition of sealing material. The system seals itself automatically when the cartridge is assembled, removing the contamination risk associated with manual mineral oil addition while maintaining evaporation prevention.
Solution Approach 2:
The sealing layer is prepared and positioned in advance during cartridge manufacturing, before the sample is loaded. This preliminary sealing preparation eliminates the need for post-loading contamination risk, as the seal is already in place and requires no manual intervention.
4Stress or pressure
If no proper cap is used to allow thermal expansion, then pressure stability is improved, but sample may spill during movement exposing technicians to pathogens or toxic reagents
Solution Approach 1:
The sealing wax layer undergoes phase transition from solid to liquid during heating, allowing thermal expansion and pressure stability. When cooled, it re-solidifies to provide a secure seal that prevents sample spillage during handling and transport, thus resolving both requirements simultaneously.
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 microreactor effectively prevents fluid loss and contamination by allowing thermal expansion without mechanical stress, ensuring accurate reaction conditions and safe disposal.
Implementation Method 1
the meltable portion also has cavities for receiving a sample for analysis. Thus, during use, the meltable portion completely or partially melts, allowing thermal expansion inside the reactor.
Implementation Method 2
the meltable portion completely or partially melts, allowing thermal expansion inside the reactor
Implementation Method 3
However, the melted material is immiscible with the sample, thus preventing mixing with the sample during the high temperature phase of a reaction.
Implementation Method 4
After use, the melted material re-solidifies, preventing contamination and re-sealing the chamber for ease of transport and use.
Data Source
AI summary
A microreactor includes a shell structure (2, 3), having a bottom wall (2) and a peripheral wall (3); a layer (5), accommodated in the shell structure (2, 3) and having cavities (9, 10) formed therein, the cavities being accessible form outside the shell structure (2, 3); reagents (17), arranged between the bottom wall (2) and the layer (5), at locations corresponding to the cavities (9, 10). The layer (5) is made of a meltable material that is solid at room temperature, has a melting point (TMP) lower than a maximum operative temperature (TMAX) required by reactions performable through the microreactor (1) and is not miscible with water. The melting point (TMP) may be between 50° C. and 70° C. In one embodiment, the melting point (TMP) is lower than a minimum operative temperature (TMIN) required by reactions performable through the microreactor (1).