Biosensor Laser-Sealed Capillary Chamber
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Solution Overview
Problem
Current test strips face challenges in accurately applying small sample volumes due to small capillary entrances, which is exacerbated by impaired vision and dexterity, and suffer from hematocrit interference and adhesive-related manufacturing issues.
Innovation Solution
A test strip design featuring a flared sample receiving chamber with a hydrophilic reagent layer extending to the dosing end, aiding sample introduction and reducing dose hesitation, along with a biosensor that minimizes hematocrit interference through a micro-capillary chamber and laser welding for cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capillary entrance width is reduced to decrease sample volume, then the sample volume required is reduced, but the ease of operation deteriorates due to difficulty in accurately aligning fingers with the dosing edge
Solution Approach 1:
The sample receiving chamber is divided into a flared portion and a capillary portion. The flared portion provides a larger target area for sample application, while the capillary portion maintains the small volume requirement. This segmentation allows users to easily apply samples to the larger flared area while still achieving the required small sample volume in the capillary region.
Solution Approach 2:
The invention transitions from a simple narrow capillary opening to a three-dimensional flared chamber structure. The flared portion extends in multiple dimensions, providing a larger surface area for sample application while the capillary portion constrains the volume. This dimensional expansion resolves the contradiction between large target area and small sample volume.
2Quantity of substance
If the capillary entrance width is reduced to decrease sample volume, then the sample volume required is reduced, but dose hesitation increases making sample uptake slower
Solution Approach 1:
The sample receiving chamber is segmented into a flared portion for sample application and a capillary portion for sample uptake. This segmentation allows the flared portion to serve as a sample reservoir that feeds the capillary portion, ensuring continuous sample flow and reducing hesitation.
Solution Approach 2:
The flared portion is designed to be filled with sample before the capillary portion begins uptake. This preliminary accumulation of sample in the flared reservoir ensures that the capillary entrance has immediate access to sample, eliminating the hesitation that occurs when the capillary must wait for sample to arrive.
3Reliability
If adhesives are used to seal the reaction chamber, then the chamber can be sealed, but manufacturing productivity deteriorates due to periodic shutdowns for cleaning slitters
Solution Approach 1:
The invention replaces the chemical adhesive bonding system with a mechanical laser welding system. Laser welding seals the reaction chamber without leaving residual adhesive materials that would contaminate slitters, thereby eliminating periodic shutdowns for cleaning and maintaining continuous manufacturing productivity while still achieving reliable chamber sealing.
4Object-affected harmful factors
If glass fiber filters or porous films are used to separate red blood cells, then hematocrit interference is reduced, but the sample volume required increases
Solution Approach 1:
The invention extracts the red blood cell separation function from external components (glass fiber filters or porous films) and integrates it directly into the reaction chamber structure through laser welding. This integration allows for effective hematocrit reduction while maintaining the small sample volume requirement, as the separation occurs within the chamber itself rather than requiring additional filtering components that increase sample volume needs.
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 design facilitates easy and accurate dosing, reduces hematocrit interference, and enhances manufacturing efficiency by improving user interaction and reducing production interruptions.
Implementation Method 1
The base substrate and the cover layer are laser welded to define a micro-capillary chamber
Implementation Method 2
it is known to provide test strips having a sufficiently small reaction chamber such that sample fluid is drawn therein by capillary action, which is a phenomenon resulting from the surface tension of the sample fluid
Data Source
AI summary
A test strip or biosensor comprising a base substrate on which an electrode system is formed. One or more laminate layers overlie the base substrate to form a sample-receiving chamber in which a reagent is deposited. An opening is provided from the sample-receiving chamber to the exterior of the biosensor. The layers and the base substrate are laser welded to secure the biosensor. One of the layer and base substrate is light transmissive to allow laser welding at the interface therebetween. The biosensor may be formed from a series of continuous webs that are subsequently sliced to form individual biosensors.