Microfluidic Device Pressure Control for Convective Clearance
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Solution Overview
Problem
Dialysis devices face challenges in increasing convective clearance of solutes while maintaining safe hematocrit levels, as conventional methods require larger channel lengths, increased blood flow, and residence time, which can lead to unsafe hematocrit levels.
Innovation Solution
A microfluidic device with multiple layers and interchannel flow barriers, including infusate, blood, and filtrate channels, where pressure profiles are controlled to maintain a consistent pressure difference, allowing for increased convective transport of solutes without compromising hematocrit levels by using apertures, fluid flow restriction materials, and recirculation pumps to manage fluid flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dialysis methods are used to increase convective clearance, then solute removal efficiency is improved, but hematocrit levels become unsafe
Solution Approach 1:
The device segments the fluid transport into three distinct channels (infusate channel, blood channel, filtrate channel) separated by permeable membranes. This segmentation allows independent control of each fluid stream, enabling convective clearance enhancement in the infusate channel without directly affecting blood flow dynamics and hematocrit levels in the blood channel
Solution Approach 2:
The patent applies different pressure profiles to different channels locally. The infusate channel maintains higher pressure to drive convective flow and solute removal, while the blood channel maintains controlled pressure to preserve safe hematocrit levels. This local quality differentiation resolves the contradiction by allowing high convective clearance where needed without compromising blood safety
2Productivity
If channel length is increased to improve convective clearance, then solute transport efficiency is improved, but device size increases
Solution Approach 1:
The patent transitions from one-dimensional linear channel flow to a three-dimensional multi-channel structure with perpendicular infusate and blood channels. This dimensional change allows simultaneous achievement of adequate residence time and convective clearance without proportionally increasing channel length, as the perpendicular arrangement increases effective exchange surface area within a compact footprint
3Productivity
If blood flow rate is increased to improve convective clearance, then solute removal is improved, but residence time decreases and hematocrit safety is compromised
Solution Approach 1:
The patent introduces infusate as an intermediary fluid that carries solutes across the permeable membrane from the blood channel. This intermediary mechanism enables convective clearance without requiring increased blood flow rate, thereby maintaining adequate residence time and safe hematocrit levels while achieving enhanced solute removal through the infusate-mediated transport process
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 higher convective clearance without increasing the device size, maintaining safe hematocrit levels and ensuring efficient solute transport through controlled pressure profiles and fluid management.
Implementation Method 1
a pressure control feature to control a difference between the second pressure profile and the third pressure profile along a length of the filtrate and blood channels
Implementation Method 2
an interchannel flow barrier separating the infusate channel and the blood channel allowing a portion of fluid flowing into the inlet of the infusate channel to flow through the interchannel flow barrier and into the blood channel
Implementation Method 3
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.