This guide describes how to generate a controlled flow inside a microfluidic chip and stop it completely (stop flow) by using an Elveflow® pressure control instrument (OB1) and a MUX Cross Chip.
Stopped-flow technology is frequently used to monitor rapid (bio)chemical reactions with high temporal resolution, e.g., in dynamic investigations of enzyme reactions, protein interactions, or molecular transport mechanisms.
First introduced in 1940 by Chance et al. and improved in 1964 by Gibson et al., stopped-flow technology is a highly versatile and convenient method for monitoring fast reactions.
The following video shows a stop flow experiment using fluorescent microspheres (sample) in poly-ethylene glycol (buffer medium) are used.
In order to perform a stop flow experiment, the sample must be miscible in the buffer medium and they must have the same density.
Three different setups are possible depending on the application and the number of inlets and outlets on the microfluidic chip.
The following setup allow a very good control of the sample in the microfluidic chip and is capable to stop the flow instantaneously but it is also possible to use two simpler setups with 3/2 valves using this application note.
Please note that in order to ensure a good zero flow performance, the sample solution has to be miscible and must have the same density as the buffer medium that fills the microfluidic system.
Results of a wide variety of applications can be improved by achieving stop flow in a microfluidic chip, from cell migration study due to chemotaxis (Yang et al., 2015) and precisely measure the performance of a microfluidic fuel cell (Cuevas-Muñiz et al. 2012) to long-term cell culture and detection (Sang et al. 2015).
This feature is also key in microscope-based projection photolithography and the formation of non-spherical particles (Dendukuri et al. 2007). Controlling perfectly how to stop the flow enables to decrease the number of imperfections on polymeric microparticles formed in situ and the automation increases the rate of formation. The advantage of the set-up including the MUX Cross Chip is mostly to work at very low volumes which is an interesting feature when one needs to reduce the mixing times, study reaction kinetics or minimize the volume in IR spectroscopy.
The MUX Cross Chip is a matrix of microfluidic valves that can be used for multiple applications, including stop flow but also phase injection sequences, flow focusing, etc. Setting the pressure applied by the OB1 pressure controller at 0 mbar is not sufficient to totally stop instantaneously the flow as the pressure can take some time to stabilize, thus creating some residual flow at first. A setup using a MUX Cross Chip has been developed to balance the pressure between the inlet and the outlet of the microfluidic chip, by applying the pressure from the OB1 flow controller. A syringe is used to perform a low volume injection experiment where the sample can be perfectly injected and controlled inside the chip. For example, it is possible to flow the sample both ways in the chip by applying successive positive and negative flows.
The sample is injected into the microfluidic chip using a syringe and a T-junction.
Be sure that all the cables and tubing are well connected to the Elveflow devices (USB cable, 24V DC, etc).
Perform leakage tests and remove any air bubble before starting the experiment to ensure a good flow regulation. This step is extremely important since air bubbles can contract or expand depending on the pressure applied, preventing the stop flow experiment to be instantaneous.
The MUX Cross Chip is a matrix of 4 x 4 valves. Connect any of the 4 inputs with any of the 4 outputs and open/close the valves using the software.
Flow controller OB1
MUX Cross Chip
Flow sensor
Fluidic 268 chip from microfluidic ChipShop
T-junction connector, tubing, fittings and reservoirs
A syringe
MAY THE FLOW BE WITH YOU
This configuration allows the injection of a little volume of sample into the T-junction when pushing the syringe plunger as the pressure at the inlet and outlet of the chip is equal to the pressure at the waste reservoir (atmosphere pressure). The syringe can then be removed and a cap can be put on the T-junction.
This configuration connects the inlet of the microfluidic chip with the OB1 and the outlet with the waste reservoir thus creating a positive flow. Applying a negative flow is also possible using the following configuration:
This configuration balances the pressure between the inlet and the outlet of the chip with good stability thanks to the pressure applied by the OB1, stopping the flow almost instantaneously.
Congratulations! You completely stopped the flow by using an Elveflow OB1 a MUX Cross Chip!
How can we help you?
Name*
Email*
Message
Newsletter subscription
We will answer within 24 hours
By filling in your info you accept that we use your data.
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!
Microfluidics is the science of handling small amounts of liquids, inside micrometer scale channels. Discover how to handle fluids for your microfluidic experiments.
This application note demonstrates a smart use ouf Elveflow's Pressure sensor and sensor reader for Direct-Ink-Writing flow control.
Learn how to set up your development environment for Elveflow products with this comprehensive tutorial.
This user guide will show you how to run microfluidic colocalization studies of single molecule spectroscopy.
This application note explores the basic principle of pneumatic pumps and a flow controller based on the basic principle of pneumatic pumps, known as pressure driven flow control. It also demonstrates the applications of pressure driven flow control in a range of industrial & research fields.
Study the impact of molecular transport on cell cultures with a cross flow membrane chip and microfluidic instruments.
Precise liquid injection system for manipulation of small volumes of fluids using the MUX distribution and the MUX recirculation valve.
This application note explains how to set up a robust and reproducible microfluidic platform for liposomes assembly with improved encapsulation efficiency and reduced polydispersity in size.
Single-wall carbon nanotubes (SWCNTs) are considered as quasi 1-dimensional (1D) carbon nanostructures, which are known for their outstanding anisotropic electronic, mechanical, thermal and optical properties.
This application note describes how to combine and synchronise liquid perfusion and imaging using an Olympus spinning disc confocal microscope together with an Elveflow pressure-driven flow controlled microfluidic system.
Mixing is a crucial step for several microfluidic applications like chemical synthesis, clinical diagnostics, sequencing and synthesis of nucleic acids
This application note describes how microfluidic can be employed as a nanoparticle generator based on the example of PLGA bead generation.
Learn how to perform PLGA nanoparticle preparation with Elveflow instruments and a microfluidic chip
The application note describes how to convert various units of shear stress and/or pressure from one to another: shear stress conversion from Pascal, atmosphere, and N/m²...!
Get a quote
Collaborations
Need customer support?
Serial Number of your product
Support Type AdviceHardware SupportSoftware Support
Subject*
I hereby agree that Elveflow uses my personal data Newsletter subscription
Message I hereby agree that Elveflow uses my personal data Newsletter subscription