Microfluidic Dialysis Device Pressure Control
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Solution Overview
Problem
Dialysis devices face challenges in increasing convective clearance of solutes while maintaining safe hematocrit levels, as reducing fluid to red-blood cell volume in blood channels can lead to unsafe hematocrit levels.
Innovation Solution
A microfluidic device with multiple layers and interchannel flow barriers, including permeable membranes and pressure control features, is designed to manage pressure profiles across infusate, blood, and filtrate channels, ensuring a consistent pressure difference and fluid flow to enhance convective transport without compromising hematocrit levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fluid to red-blood cell volume in the blood channel is decreased to increase convective clearance, then the convective clearance of solutes is improved, but the hematocrit level becomes unsafe
Solution Approach 1:
The patent introduces a fourth channel (filtrate channel) adjacent to the blood channel, creating a new spatial dimension for solute removal. By applying transmembrane pressure perpendicular to the blood flow direction, solutes are cleared through the membrane into the filtrate channel without requiring reduction of fluid to red-blood cell volume in the blood channel, thus maintaining safe hematocrit levels while achieving enhanced convective clearance
Solution Approach 2:
The patent uses a permeable membrane as an intermediary between the blood channel and filtrate channel. This membrane enables selective transport of solutes from the blood channel to the filtrate channel under applied pressure, allowing convective clearance to occur without directly altering the fluid dynamics within the blood channel that would compromise hematocrit safety
2Productivity
If the device size is increased to improve convective clearance, then the solute removal efficiency is improved, but the device complexity and size increase
Solution Approach 1:
The patent utilizes the transmembrane direction (perpendicular to blood flow) as an additional dimension for mass transfer. By applying pressure gradient across the membrane thickness, convective clearance occurs in this fourth dimension without requiring extension of the channel length or increase in device footprint, thereby achieving high solute removal efficiency in a compact configuration
Solution Approach 2:
The patent embeds the filtrate channel and membrane structure within or adjacent to the blood channel assembly, creating a nested or closely integrated configuration. This allows the clearance function to be incorporated without proportionally increasing overall device size, as the filtrate channel and membrane are positioned to maximize surface area for mass transfer within a compact volume
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 device achieves increased convective clearance of solutes while maintaining safe hematocrit levels, allowing for higher efficiency in solute removal without the need for larger device sizes or increased blood flow.
Implementation Method 1
The pressure difference between the blood channel and the filtrate channel is controlled such that it varies by less than 50% of the pressure difference between the blood channel and the filtrate channel at an upstream end of the blood channel and the filtrate channel
Implementation Method 2
A first membrane separates the infusate channel from the blood channel and a second membrane separates the blood channel from the filtrate channel
Data Source
Figure 1A
Figure 1B
Figure 1C
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.