Capillary Wiper Structure for Accurate Blood Sample Volume
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Solution Overview
Problem
Point-of-care analyzers often produce erroneous results due to over-fill or under-fill situations caused by improper handling of capillary tubes, which are typically used to collect blood samples, leading to inaccurate test volumes.
Innovation Solution
A capillary wiper is integrated into a disposable test cartridge to ensure the correct sample volume is presented for analysis by removing excess sample from the outer surface of the capillary tube, preventing over-filling and under-filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the capillary tube is used to collect blood sample without a wiper, then the sample collection is simple and quick, but the test volume becomes inaccurate due to over-fill or under-fill situations
Solution Approach 1:
The wiper is integrated directly into the capillary tube structure, merging the sample collection function with the excess sample removal function into a single unified device. This eliminates the need for separate wiping actions or additional components while ensuring accurate test volume.
Solution Approach 2:
The wiper acts as an intermediary element between the capillary tube and the test chamber. It mediates the sample transfer process by selectively removing excess sample from the capillary tube exterior while allowing the correct volume to enter the test chamber, thus ensuring volume accuracy.
2Manufacturing precision
If the user manually wipes the capillary tube, then excess sample is removed, but the user may accidentally draw sample out of the capillary tube causing under-fill
Solution Approach 1:
The wiper is designed to automatically perform the wiping function as the capillary tube is inserted into the test chamber. The system serves itself by using the insertion motion to activate the wiper, which removes excess sample without requiring any additional manual wiping actions from the user. This eliminates the risk of user error while maintaining sample volume control.
Solution Approach 2:
The wiper is pre-positioned and pre-configured to engage with the capillary tube during insertion. The excess sample removal action occurs automatically as part of the insertion process itself, before the sample reaches the test chamber. This preliminary action ensures that the correct volume is established before testing begins.
3Manufacturing precision
If a wiper is added to the capillary tube system, then sample volume accuracy is improved, but the device complexity and potential for user error increase
Solution Approach 1:
The wiper is merged with the capillary tube as an integrated component rather than a separate accessory. This combination ensures that the volume control function is built into the sample collection device itself, eliminating the need for separate wiping steps or additional user actions. The result is improved sample volume accuracy without compromising operational simplicity.
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 capillary wiper ensures accurate test results by maintaining the correct sample volume, even when used by minimally-trained healthcare workers, reducing errors and maintaining consistency with central laboratory standards.
Implementation Method 1
a tubular, capillary wiper having a pipette-shaped longitudinal cross-section with a tapered, elastomeric bottom portion and a top opening having a cross-sectional area greater than the cross-sectional area of a capillary tube used with the disposable test cartridge and a bottom opening having a cross-sectional area smaller than the cross-sectional area of the capillary tube
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A disposable test cartridge and method for a point-of-care analyzer includes a cartridge body having a plurality of chambers where each of the plurality of chambers has an opening at a top of the cartridge body, a cartridge cover connected to the cartridge body where the cartridge cover has a capillary-receiving aperture, a capillary wiper disposed within the capillary-receiving aperture where the capillary-receiving aperture is aligned with one of the plurality of chambers of the cartridge body, and a capillary element removably insertable into the cartridge cover where the capillary element has a capillary tube that extends into the capillary-receiving aperture and through the capillary wiper where a tip portion of the capillary tube extends into the cartridge body.