Microreactor with Segmented Outflow for Independent Cell and Product Control
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Solution Overview
Problem
Conventional continuous culture systems face challenges in independently controlling growth rate, cell density, and product concentrations, especially in small-scale bioreactors, due to difficulties in fluid flow measurement and control, and the inability to maintain constant cell density at non-zero growth rates.
Innovation Solution
A microreactor with a reaction chamber comprising two sub-chambers and a flexible membrane system allows for independent control of cell and molecule dilution rates by varying the volumes and flow rates through unfiltered and filtered output ports, using a method that adjusts the ratio of dilution rates and maintains a constant average volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemostat control is used to maintain steady state cell concentration, then cell density can be controlled, but product concentrations cannot be directly controlled and washout occurs at high growth rates
Solution Approach 1:
The system segments the outflow into two separate streams: one filtered stream for cell retention and one unfiltered stream for product removal. This allows independent control of cell density (via filtered outflow rate) and product concentration (via unfiltered outflow rate), resolving the contradiction between maintaining steady state and enabling product concentration control.
Solution Approach 2:
A filter is introduced as an intermediary component between the bioreactor and the outflow. The filter separates cells from the medium, enabling differential removal rates of cells versus products. This intermediary allows the system to maintain cell density while independently controlling product concentration, preventing washout at high growth rates.
2Productivity
If turbidostat control is used to maintain cell density at maximum growth rate, then cells can be maintained at maximum growth rate, but product concentrations cannot be directly controlled
Solution Approach 1:
The segmented outflow system allows the turbidostat to maintain maximum growth rate via filtered outflow control while the unfiltered outflow provides independent product concentration control. This resolves the contradiction by separating the control functions that were previously coupled in single-outflow systems.
3Stability of the object's composition
If conventional continuous culture is used, then steady state can be maintained, but independent control of multiple parameters (cell density, product concentration, growth rate) is not achieved
Solution Approach 1:
By segmenting the outflow into filtered and unfiltered streams, the system maintains steady state through controlled cell retention while providing flexible independent control of multiple parameters (cell density via filtered outflow, product concentration via unfiltered outflow, growth rate via dilution rate). This resolves the contradiction between stability and operational flexibility.
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
This approach enables precise control over cell density and product concentrations, allowing for optimal growth rates and productivity in small-scale bioreactors, overcoming the limitations of traditional systems by maintaining constant cell density and controlling product concentrations independently.
Implementation Method 1
each sub-chamber has a flexible membrane that deforms to change the volume of the sub-chamber
Implementation Method 2
a filter that allows different dilution rates between cells and molecules
Data Source
AI summary
A microreactor with a reaction chamber comprising two sub-chambers with reconfigurable volumes, an input conduit with input valve, an un-filtered output conduit with first output valve, and a filtered output conduit with a second output valve is used to perform a method to control a different dilution rate for cells and molecules in continuous culture bioprocesses. In preferred embodiments flow control is achieved using the difference in volume of the two sub-chambers.