Discharge Device with Segmented Liquid and Bacterial Filters
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Solution Overview
Problem
Generic discharge devices for pharmaceutical liquids face issues where medium can contaminate the bacterial filter due to air cushion formation when the device is tilted, leading to surface tension issues that prevent air from entering the reservoir for pressure equalization, and increasing filter pore size compromises bacterial filtration.
Innovation Solution
The discharge device features two filters spaced apart with a free space, where air passes through both filters during pressure equalization, and the liquid path is separate from the filters, ensuring the liquid does not reach the bacterial filter, with a liquid filter designed to prevent medium passage until excess opening pressure is reached, and filters with differing pore sizes to manage surface tension effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pore size of the bacterial filter is increased, then air flow through the filter is improved, but bacterial filtration capability deteriorates
Solution Approach 1:
The filter system is segmented into two distinct filters: a liquid filter with larger pores (e.g., 10 μm) positioned closer to the medium reservoir, and a bacterial filter with smaller pores (e.g., 0.2 μm) positioned farther away. This segmentation allows each filter to be optimized for its specific function - the liquid filter handles bulk liquid removal with high flow capacity, while the bacterial filter provides fine filtration with smaller pores, resolving the contradiction between air flow and bacterial filtration capability.
2Reliability
If the pore size of the bacterial filter is decreased, then bacterial filtration capability is improved, but surface tension increases preventing air entry
Solution Approach 1:
The liquid filter acts as an intermediary element between the medium reservoir and the bacterial filter. It captures and retains liquid medium in its larger pores, preventing the medium from reaching the bacterial filter. This intermediary function eliminates the harmful effect of surface tension in the bacterial filter pores, allowing air to flow freely through the bacterial filter without being blocked by liquid, thus maintaining both high bacterial filtration capability and good air flow.
3Device complexity
If a single filter is used for both liquid and bacterial filtration, then device complexity is reduced, but filter contamination and malfunction occur
Solution Approach 1:
Instead of using a single filter for both liquid and bacterial filtration, the system is segmented into two specialized filters: a liquid filter with larger pores for bulk liquid removal and a bacterial filter with smaller pores for fine filtration. This segmentation prevents medium contamination of the bacterial filter, ensuring reliable operation of both filtration functions while maintaining acceptable device complexity through the modular arrangement.
4Reliability
If the liquid filter retains medium through surface tension, then bacterial filter protection is improved, but pressure equalization is prevented
Solution Approach 1:
The two filters are positioned at different locations within the pressure equalization channel, creating local quality differences. The liquid filter is positioned closer to the medium reservoir where liquid is present, while the bacterial filter is positioned farther away in a region where only air should be present during pressure equalization. This spatial arrangement ensures that the liquid filter provides local protection to the bacterial filter while allowing pressure equalization to proceed without obstruction.
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 design prevents medium from reaching the bacterial filter, ensuring effective air entry for pressure equalization and maintaining filter integrity, even when the device is tilted or pressurized, without compromising bacterial filtration.
Implementation Method 1
the small pore size of the bacterial filter leads to a high surface tension of the medium in these pores
Implementation Method 2
a filter arrangement in the area of the pressure compensation channel, which filters microbacteria from the inflowing air by means of a bacterial filter
Implementation Method 3
a pressure equalization channel to be routed from an external environment to the medium reservoir, through which air can flow
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The device (10) has a medium reservoir (20) for receiving a fluid medium, and a discharge opening (32) for discharging the fluid medium from the medium reservoir. A pressure balancing channel (40) is lead into the reservoir. A micro-biologically effective filter arrangement (44) has a fluid filter (52) pointing to the reservoir and a bacteria filter (50) pointing away from the reservoir, where the bacteria filter and the bacteria filter have filter pores. The bacteria filter and the fluid filter are arranged inside the pressure balancing channel in series.