Flow control

Active flow control

On-chip flow control enables the design of simpler, more compact microfluidic devices, which can lead to cost reductions in the resulting system. We can design these chips to integrate a large variety of functions, thereby reducing the need for manual handling between process steps.
An example of an added function is the active mixer chip, which allows asymmetric volumes to be mixed. Watch the movie below to see how this works. Additional functions for on-chip integration can include:

Accurate volume sampling
Spatial and temporal control over fluid flows
Mixing of asymmetric volumes
Multiple washing steps
Incubation and heating
PCR or other thermal-cycling capabilities
Detection and sensor integration

Our active flow control systems are based on fully integrated membrane valves and pumps. The reliable on-chip valve and pump technologies are based on visibly clear materials, which can be actuated through pneumatic control systems.

The valves and pumps can be provided in a selection of materials and hybrid combinations. All of which are designed to meet application-specific needs and customer requirements.

Materials and hybrid combinations

COC devices with COP membranes
Full COC devices
Glass devices with PDMS membranes
Full glass devices
And many more

Capillary-based flow control

Over the years we have built up a robust technology for developing autonomous microfluidic devices, which integrate on-chip flow control and are based on capillary action. With this technology we are now able to target Point-of-Care (PoC) applications. At Micronit, we are driven by the need to yield a simple and compact microfluidic device, that delivers different liquids in a specific time sequence and uses minimal external pumping equipment. We are capable of enabling our customers to perform multistep assessments on single-use microstructured devices, with improved temporal and spatial control.

Capillary burst valves

In order to fulfil the PoC application requirements, the fluidic movement inside the channels of our systems is based on capillary action. The key points are:

Tuning the surface chemistry to assure capillary filling by developing the appropriate functionalisation strategy; and
Adjusting the geometry to discover the best way to stop the capillary flow.

We have gained a lot of experience working with these two key points, and placed a lot of effort in developing devices that integrate capillary burst valves. The valves rely on an abrupt increase in the cross-section of a microfluidic channel, which causes the capillary filling to stop at the transition.

Electrostatic triggering

Electrostatic actuation of capillary burst valves is an effective way of triggering the liquid after the valve. What is more, it is required to develop a reliable, multistep, on-chip assessment. The operation principle lies in applying a voltage between two electrodes which are placed in front of and behind the valve. This order attracts the meniscus towards the second electrode and triggers the valve. By bringing these two elements together, we can yield autonomous devices that require little operational power and are suitable for use in handheld instruments.

Our polymer-based technological approach

At Micronit, we recognise that a crucial point for delivering an autonomous, cost-efficient microfluidic assembled chip is to use cheaper and more easily accessible materials. That is why we focus on developing our polymer substrate technology and are capable of integrating functional elements, capillary valves and metal electrodes in a polymer-based microfluidic chip.