Microfluidic Cartridge Passive Capillary Sample Transport
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Solution Overview
Problem
Existing liquid sample processing cartridges face challenges in efficient and user-friendly operation, particularly in hospitals and general practitioner offices, where sample intake and processing need to be quick, reliable, and minimally invasive, with existing technologies relying on active pumping mechanisms or complex flow control.
Innovation Solution
A cartridge with a microfluidic system featuring intake and storage capillary channels and a flow control element that utilizes capillary suction pressures to autonomously transport samples from an intake port to a processing chamber, allowing for passive filling and controlled sample forwarding without active pumping, using a hydrophilized surface and geometric design to manage capillary pressures and flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active pumping mechanisms are used to transport liquid samples, then sample transport speed and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces active mechanical pumping mechanisms with passive capillary forces generated by surface tension and wettability differences. The microfluidic channels are designed with specific hydrophilic/hydrophobic surface properties that automatically drive liquid flow from the sample application area through reaction chambers without external pumps, thereby reducing device complexity while maintaining transport reliability
Solution Approach 2:
The microfluidic system is designed to transport samples autonomously using self-generated capillary pressures. The channels and chambers are engineered with specific surface treatments that create inherent flow驱动力, allowing the system to serve itself without external active pumping components
2Device complexity
If capillary forces are used for sample transport, then device complexity is reduced, but control precision over flow rates decreases
Solution Approach 1:
The patent optimizes capillary flow control by precisely adjusting geometric parameters of the microfluidic channels (width, height, length) and surface energy parameters (wettability, contact angle). These parameter optimizations enable predictable flow rates and improved sample processing speed while maintaining the simplicity of passive capillary-driven transport
Solution Approach 2:
The system incorporates dynamic control elements such as valves or flow resistors that can be activated to regulate capillary flow at critical points. This allows temporary modification of flow characteristics without converting to active pumping, balancing control precision with device simplicity
3Ease of operation
If multiple vent holes are used for stepwise liquid transport, then flow control is improved, but manufacturing complexity increases
Solution Approach 1:
The patent integrates multiple venting functions into a single unified venting structure or combines vent holes with existing channel features. This merging approach maintains the capability for stepwise flow control through multiple chambers while reducing the total number of separate manufacturing steps and features required
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
Enables convenient, reliable, and minimally invasive sample processing with short filling times and precise control, ensuring error-free sample transport to the processing chamber, suitable for small sample volumes and optical measurements, while being cost-effective and easy to manufacture using injection molding techniques.
Implementation Method 1
A first capillary channel, called 'intake capillary channel' in the following and that connects the intake port to the storage chamber, the intake capillary channel having an intake capillary suction pressure. A second capillary channel, called 'feeding capillary channel' in the following and that connects the storage chamber to the processing chamber, the feeding capillary channel and processing chamber having a feeding capillary suction pressure.
Data Source
Figure 1
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AI summary
The invention relates to a cartridge (10) for processing of a liquid sample, for example for the detection of components in a sample of blood. The cartridge comprises a fluidic system with an intake port (12) leading via an intake capillary channel (13) to a storage chamber (14). Moreover, a feeding capillary channel (15) leads from the storage chamber (14) to a detection chamber (16). The design of the cartridge (10) is such that the intake capillary channel (13) that connects the intake port (12) to the storage chamber (14), has a capillary suction pressure sufficiently high to drive some sample from the intake port to the storage chamber without need of any additional pressure. Furthermore the cartridge a flow control element (18, 20) adapted to be externally controllable such that the sample can be drawn from the storage chamber (14) towards the processing chamber (16) without any active pumping.