Published on 27 August 2019

Setup : OB1 MK3 pressure controller + MUX Inj + Flow Sensor + ALine Inc Organ on a Chip
In this application note, we walk you through the steps of setting up a unidirectional fluid recirculation through a semi permeable membrane. The MUX Recirculation is a bidirectional 6-port / 2 position valve allowing to perform switches between two set-up configurations. One application is to make a recirculating set-up with a flow rate always going through the chip in the same direction. It also possible to perform recirculation using 3/2 valves.
The injection loop consists of a network of inputs/outputs that can be connected to each other in two configurations.
Its very low internal volume (Stator- 0.2 ÎĽL/hole, Rotor Seal- 1.3 ÎĽL/groove) makes it the ideal valve to perform the injection of a controlled volume of sample into a chip.
The Mux Inj has 6 inputs and two configurations shown on the image below.
Each input is connected to a neighbor output, either on the right or the left depending of the configuration.
Configuration 1
Configuration 2
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Cell culture on chip
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Live cell imaging
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Cell response to medium change
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Drug screening
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Toxicity tests
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Stem cells assays
Fluid recirculation: Material & Methods

We are using here an organ on a chip to show case the recirculating setup.
This chip, from ALine Inc, is a two input two output chips. It consists of two channels, one upper channel and one above channel, separated by a semi permeable membrane. The idea of the experiment is to have a continuous and constant flow of for instance cell nutriment in the upper channel. This nutriment is recirculating during a given period of time. In the below channel, there is a continuous flow (for instance, of cells) which is not a recirculating flow.
This experiment showcases how the nutriments diffuse through the membrane and which amount of the initial quantity of nutriment has been consumed by the cells. We are here using a blue dye to mimic the nutriment.
[ooc_rebound]
Fluid recirculation: Setup diagram
Warning : Make sure that the tubes are correctly inserted into the Mux Inj to prevent any leakage. The tube should reach the bottom of the connector in order to perform a waterproof connection. After inserting the tubes, tighten the spanner to ensure the sealing.
Step-by-step control with the Elveflow® smart interface
The Elveflow® smart interface allows to synchronize the OB1 MK3 pressure controller together with the Mux Inj in order to perform a recirculating set-up. This software is thought to run long term experiment thanks to the powerful sequencer which can perform the switch between reservoirs automatically either after a predetermined period of time or, in combination with a flow sensor, after a chosen amount of sample as gone through the chips.
Learn also how to perform medium recirculation for dynamic cell culture.
Microfluidics knowledge
Do you want tips on how to best set up your microfluidic experiment? Do you need inspiration or a different angle to take on your specific problem? Well, we probably have an application note just for you, feel free to check them out!

















