Microfluidic Dialysis Device Pressure Profile Control
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Solution Overview
Problem
Dialysis devices face challenges in increasing convective clearance of solutes while maintaining safe hematocrit levels, as traditional methods require larger channel lengths, increased blood flow, and residence time, which can lead to unsafe hematocrit levels and membrane damage.
Innovation Solution
A microfluidic device with a controlled pressure profile system, including a first and second interchannel flow barrier, and controllable flow control devices to manage pressure differences between infusate, blood, and filtrate channels, ensuring a constant hematocrit level and efficient convective clearance without significant increases in device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the channel length is increased to improve convective clearance, then the clearance efficiency is improved, but the device size increases and hematocrit levels become unsafe
Solution Approach 1:
The patent transitions from a single linear channel to a three-dimensional stacked channel architecture with multiple layers. This vertical dimensionality change allows multiple channels to occupy the same footprint area, increasing the effective channel length and clearance capacity without proportionally increasing the device's overall length or footprint.
Solution Approach 2:
The patent implements nested channels where infusate channels, blood channels, and filtrate channels are interlaced and positioned in close proximity to each other in a stacked configuration. This nesting allows the channels to share common structural support and membrane interfaces, maximizing the use of available space while maintaining safe hematocrit levels through optimized flow paths.
2Productivity
If the blood flow rate is increased to improve convective clearance, then the clearance efficiency is improved, but the hematocrit level becomes unsafe
Solution Approach 1:
The patent divides the blood flow path into multiple separate blood channels that are distributed across stacked layers. This segmentation allows the total blood flow to be distributed across multiple parallel pathways, maintaining adequate flow rates for clearance while preventing excessive concentration of blood cells in any single channel, thus maintaining safe hematocrit levels.
Solution Approach 2:
By stacking multiple channels in the vertical dimension, the patent increases the total cross-sectional area available for blood flow without increasing the horizontal footprint. This allows higher overall blood flow rates to achieve improved clearance while distributing the flow across multiple channels to maintain safe hematocrit levels in each individual channel.
3Productivity
If the transmembrane pressure is increased to improve convective clearance, then the clearance efficiency is improved, but the membrane becomes damaged
Solution Approach 1:
The patent employs local quality by implementing support structures and structural reinforcements at specific locations within the channel assembly, particularly at the membrane interfaces. This localized structural enhancement allows the membrane to withstand higher transmembrane pressures required for improved clearance without compromising overall membrane integrity, as the support is provided precisely where mechanical stress is concentrated.
Solution Approach 2:
The patent utilizes composite material structures combining the selective membrane layer with supporting structural layers and channel walls. This composite construction provides both the filtration functionality of the membrane and the mechanical strength needed to withstand elevated transmembrane pressures, enabling improved convective clearance while protecting the membrane from damage.
4Productivity
If the device size is increased to improve convective clearance, then the clearance efficiency is improved, but the device complexity and footprint increase
Solution Approach 1:
The patent resolves the contradiction by stacking multiple channels in the vertical dimension rather than expanding horizontally. This allows the device to achieve high convective clearance capacity equivalent to much longer single channels while maintaining a compact footprint, as the increased effective channel length is achieved through vertical layering rather than horizontal extension.
Solution Approach 2:
The nested stacked channel configuration allows multiple functional channels to be integrated within a compact volume. The infusate, blood, and filtrate channels are interlaced and share common structural elements and membrane interfaces, maximizing the clearance capacity within a minimal footprint by efficiently utilizing three-dimensional space.
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 system achieves higher convective clearance levels while maintaining safe hematocrit levels and reducing membrane damage by controlling pressure profiles and fluid flow, enhancing the efficiency and safety of dialysis processes.
Implementation Method 1
The first controllable flow control device is configured to actively control a slope of a third pressure profile along a length of the filtrate channel relative to the slope of a second pressure profile along the length of the blood channel
Implementation Method 2
Convective clearance of solutes from blood in the device is determined by the transmembrane pressure in the device
Data Source
AI summary
A microfluidic device for increasing convective clearance of particles from a fluid is provided. In some implementations, described herein the microfluidic device includes multiple layers that each define infusate, blood, and filtrate channels. Each of the channels have a pressure profile. The device can also include one or more pressure control features. The pressure control feature controls a difference between the pressure profiles along a length of the device. For example, the pressure control feature can control the difference between the pressure profile of the filtrate channel and the pressure profile of the blood channel. In some implementations, the pressure control feature controls the pressure difference between two channels such that the difference varies along the length of the channels by less than 50% of the pressure difference between the channels at the channels' inlets.