Droplet & Particle generation

The science of flow control for emulsion and particle production

An emulsion is a heterogeneous system consisting of at least one immiscible liquid dispersed in another in the form of droplets. Salad dressings are common examples of emulsions. Droplet production using microfluidic systems was implemented for applications where monodispersity is of high importance as compared to batch methods. Within micrometer-sized channels, one droplet at a time is generated, allowing for the production of volumes of monodisperse droplets. With this level of control, applications that would not have been possible have emerged, such as digital PCR and single-cell encapsulation within droplets. It is also an excellent method for applications that use expensive API (Active Pharmaceutical Ingredient), as it produces less waste.
Main benefits
  • High monodispersity
  • High control
  • High encapsulation efficiency
  • Avoid loss of expensive reagents

Main applications

PLGA microcapsule microfluidic

Drug delivery

In recent years, biodegradable microcapsules/microparticles have gained widespread importance in the delivery of bioactive agents.  Polymer based microcapsules/microparticles are one of the most successful new drug delivery systems. They can be used in various areas, such as long-term release systems, vaccine adjuvant, and tissue engineering. Droplet based microfluidics allows highly monodispersed droplet and microcapsules/microparticles production opposed to  batch emulsion methods and provides an “In-line” continuous droplet production process.

Formulation

The encapsulation of active ingredients such as flavors or fragrances for cosmetics and food products is a key step in these areas. One of the most important challenges in encapsulation isto prevent the leakage of the encapsulated species. The possibility to encapsulate these compounds allow one to control the release of the compound and have improved pharmacokinetics.

drop seq next generation sequencing

Next generation sequencing (NGS)

Encapsulation of single cell inside droplet allow to increase NGS efficiency. The ability to study cell at single cell level using droplet based systems combined withNGS techniques allow for the sequencing of the mRNA from a large number of cells. The power of this technology resides in the fact that during sequencing, one can distinguish where the original information came on a cell to cell basis. This allows one to make a gene expression map of the cell, or even to distinguish cell populations within a tissue.

Drug discovery

In vitro cell culture is a fundamental component of biological production systems and biotechnological research. The ability to grow cells outside of their natural environment offers many possibilities ranging from high quantity production of enzymes to cell toxicity studies and drug discovery.

Droplet microfluidics allows one to encapsulate single or multiple cells into tiny droplets of pL volume which are generated at a rate of approximately one thousand per second.

digital pcr microfluidic

Diagnostics

A key measurement challenge in diagnostic research involves identifying small changes in nucleic acid sequence that are commonly associated with genetic diseases such as Down’s syndrome, and many cancers. Digital PCR (dPCR) carries out a single reaction within a sample as standard PCR, however the sample is separated into a large number of partitions where reactions take place in each partition individually. This is an excellent solution to partition a sample, and dPCR technology that make use of droplet microfluidics is often called droplet digital PCR (ddPCR).

Fluid handling and droplet control

When it comes to droplet or particle generation, having control of the fluid delivery system is important. During droplet or particle production the flow rate of each phase must remain constant and stable to allow the production of monodisperse droplets.

The possibility to control the flow rate of each phase allows for more control over the process, to precisely and easily regulate the size of the droplet or particle generated.  

Read more on the expertise page

Analysis between Microfluidic syringe pumps and flow EZ

Flow control systems for droplet generation

Flow rate stability is critical for having repeatable reactor volumes and reproducible results. Syringe pumps are commonly used for generating droplets in microfluidic experiments. Depending on the model in use, syringe pumps show limited flow control.

As a consequence, the droplet size( proportional to the flow rate), is affected. The actual flow rate cannot be controlled with syringe or peristaltic devices. The flow rate value is displayed on the device, but no information on the time required for reaching a set flow rate is given. Tthe time for flow equilibrium may vary depending on the microfluidic setup, and flow rate can oscillate depending of the instrument. An alternative to syringe pumps are pressure-based flow controllers. These show high-precision flow control and fast response time.

Droplet stability table

Pressure control for reliable droplet generation

We compare the production of water-in-oil emulsions using microfluidic syringe pumps, and pressure-based flow controllers. Droplet size stability and the time required to reach several droplet diameters are determined for the two instruments.

For more information or a technical discussion

Contact us