Level Sensors for Microfluidics
Fail-safe instrument for automated recirculation experiments
Easy recirculation
Continuous, unidirectional flow over samples
Up to 3-week long experiments
Less manual work to maintain your long term recirculation
Plug-and-play
Save time and improve reproducibility
Fail-safe mechanism
No more losing your experiment due to clogging
Need a microfluidic SME partner for your Horizon Europe project?
Level sensors
Automated & secured recirculation system
Most automated recirculation systems rely on the initial fluid volume and desired flow rates to estimate the time for one reservoir to flow most of its volume through the sample and then switch to the other reservoir.
In cell culture, for example, as cells grow and proliferate, they release debris that can foul and clog the lines, changing the flow rates.
Even small changes can affect the time it takes for one reservoir to empty. However, the system is usually insensitive to this change. Thus, it continues to switch between reservoirs as programmed.
If one of the reservoirs empties before was expected due to biofouling or clogging, it introduces air into the system and damages the cells, ruining the experiment.
Take full advantage of controlled recirculation
To avoid this problem, our microfluidic level sensors add an extra layer of responsiveness to your system and ensure that your reservoirs are never empty.
This ensures that your experiment is always full of liquid and that you don’t risk air passing through your chamber and disrupting your sample.
The level sensors automate your system based on the actual media volume level inside your reservoirs, so changes in flow rate due to fouling are accounted for, and the time it takes to switch between reservoirs is adjusted.
In case something goes wrong, for example, leakage due to extensive clogging of the lines, the level sensors will stop the flow and preserve your sample.
Automation and control with Galileo user interface
- Detection of the Galileo flow sensor
- Reading and plotting flow rate in real time
- Display of clogging detection flag
- Record flow rate and clogging detection with an acquisition rate of up to 100 Hz
Level sensor applications for dynamic cell culture
A great asset of a cell perfusion system is providing a more physiologically relevant cell microenvironment by sustaining a constant unidirectional flow through a microfluidic chip laden with cells. In this light, limited volumes of liquid flow back and forth between two reservoirs, as seen above.
The media flow subjects cells to relevant shear stress while providing a fresh supply of nutrients at a constant level of O2 and CO2 while flushing away waste, all with a high level of control. The level sensors add an extra layer of control by introducing a fail-safe mechanism that considers the changes that can happen within such a dynamic system, such as fouling the tubing with the debris of cellular death, leakage due to clogging, and other blockage-related matters, such as the entry of air.
As illustrated below, the level sensors can be added to our automated cell culture platform or cell perfusion system.
Examples of setups using level sensors
1) Automated cell perfusion platform (Principle)
2) Cell perfusion pack with a rotary valve
3) Cell perfusion pack with active valves
These examples include the following instruments:
| 1. Automated cell perfusion platform | 2. Rotary valve recirculation | 3. Active valves |
|---|---|---|
Pressure controller Recirculation Bridge Microfluidic flow sensor (eg. Galileo) | Pressure controller Microfluidic flow sensor (eg. Galileo) Rotary valve | Pressure controller Valve controller (MUX wire) Microfluidic flow sensor (eg. Galileo) 3/2 valves |
Some applications of our microfluidic cell culture system include:
Stem cell culture
Automated and fail-safe long-term microfluidic cell culture system.
✓ Highly controlled microenvironment
✓ Fail-safe mechanism
✓ Automated sequences
Stem cell culture
Microfluidic spheroid cell culture
Plug-and-play instrument pack for automated scaffold-free 3d cell culture technique.
✓ Multiple Parallel culture of Spheroids
✓ Automated Spheroid Perfusion
✓ More Physiologically Relevant Model
Microfluidic spheroid cell culture
Blood-vessel-on-chip pack
Reproduce physiological flow conditions for vasculature assays
✓ Reproduce Physiological Shear Stress
✓ Unindirectional Flow
✓ Use the Device of Your Preference
Blood vessel formation & occlusion (Atherosclerosis)
And many more!
We have built expertise in microfluidic flow control for over ten years to provide you with state-of-the-art microfluidics systems. From biology to engineering applications, the Microfluidics Innovation Center is the perfect partner for you to get started with microfluidics.
Level sensor pack specifications
The following table summarizes the main specifications of the level sensors for microfluidics. This product is subject to optimization.
| Components | Technical Specifications |
|---|---|
| Dimensions (cm) | Sensing area: 2 x 1 cm |
| Material | Plastic |
| Reservoir compatibility | 100 mL Schott bottle |
| Control | Software (Galileo user interface) |
The level sensors are compatible with standard incubator conditions (37oC, 5% CO2, and 100% humidity). The liquid being sensed should be able to conduct current for proper functionality.
Customize your pack
Our instruments can be added to different setups depending on your specific needs. In this light, our microfluidic specialists will advise you on the best instruments and accessories depending on your needs and will accompany you during the system’s setup.
Frequently asked questions
Is the instrument compatible with other reservoirs than bottles?
The current version is compatible with 100 mL bottles, but we are working on making it compatible with small volumes. If you need a different type of reservoir, contact us using the “talk to our experts” green button above.
What extra equipment is needed?
Besides the fluid flow equipment, such as the pressure-driven flow controller, flow sensor, and chip, you will need a computer to run the software to program the automated sample collection.
Does it only work with experiments under flow?
The automated sampling unit needs to be connected to a flow generator so the automation of the process is possible. Thus, it is best adapted to microfluidics and perfusion experiments. The experiments can have continuous or intermittent (stop/go) flow.
Funding and Support
The LIFESAVER project helped develop this instrument. This project is funded by the European Union’s H2020-LC-GD-2020-3, grant agreement No. 101036702 (LIFESAVER).
Research and Innovation in Health (I3S).
Products & Associated Accessories
FAQ - Level Sensors for Microfluidics
What are Level Sensors, and what problem do they solve?
In the case of automated recirculation perfusion studies, the Level Sensors function as a safety net. The primary function of the Level Sensors is to ensure that the reservoir does not run out of liquid in the course of the long flowing cell cultures.
The sensors function by calculating the time at which the next switch of the typical automatic recirculation system will be required, considering the amount of liquid initially in the system and the expected rates of the flow. However, in the case of the presence of cell debris in the system, the predictions may go awry, and the reservoir may run out of liquid. This may result in the entry of air into the system, leading to the irreparable damage of the cell sample. The problem is resolved by the Level Sensors, which function on the real-time liquid levels in the system rather than the predictions of the time required for the next switch.
How do the Level Sensors operate at a technical level?
Unlike the typical recirculation system, the Level Sensors function by continuously monitoring the liquid levels in the system and switching the system based on the presence of the liquid in the tube. This means that the system automatically switches to the second reservoir as soon as the liquid in the first one drops below a certain threshold. This will ensure that there is no entry of air into the system, leading to the irreparable damage of the cell sample.
What happens if there’s a leak or a severe clog?
The safety net provided by the Level Sensors is not limited to the swapping of the reservoir. In the case of a leak in the system, caused by a major blockage in the tube, the Level Sensors will stop the flow of the liquid. This will ensure the protection of the cell sample and prevent unseen damage to the system while the experimenter is away.
How long can you run tests with this setup?
The level sensor setup allows tests up to three weeks in duration. This is a significant milestone in terms of long-term cell culture, which could involve the differentiation of stem cells, the maturation of organ-on-a-chip systems, or vascular biology studies, among others, in which cell behavior needs to be observed without human input for extended durations. The design makes this duration achievable.
What reservoir formats does the system accept?
Currently, the level sensor setup is only compatible with Schott bottles with a capacity of 100 mL. The product page, however, claims that development is in progress for the setup to be compatible with reservoirs with smaller capacities. If your needs require a reservoir with a different format, you may need to use a different setup.
Which software program governs the level sensors?
The Galileo user interface, used in several devices, is the software program that governs the level sensor setup. Some of the features include real-time display of the flow rate, plotting of the flow rate, a clog flag, and data logging with a maximum acquisition rate of 100 Hz. However, you need a computer to operate the software and design your own automated tests.
Can the sensor be used in an incubator?
Yes, they can be used in an incubator. The level sensors are validated for use in a standard CO2 incubator with conditions of 37°C, 5% CO2, and 100% humidity. This is important, as in order for the media temperature and the gases in the experiment to be stable, the reservoirs need to be in the incubator during the experiment.
What are the tools that need to be used in order to use the level sensor?
To use the level sensor, you need the chip/culture device, a pressure-driven flow controller, a micro fluidic flow sensor (which could be the Galileo sensor), as well as a computer running the Galileo software. The level sensor can be used in three main forms: as an active valve with a MUX wire controller, as a rotary valve recirculation configuration, as well as in an automated cell perfusion system with a recirculation bridge.
Can continuous and intermittent flow both be utilized with these sensors?
Yes. Both continuous flow and intermittent flow modes, or stop-and-go flow, can be utilized with these sensors. The fail-safe safety feature is effective in both situations, as the level sensors react to the actual liquid level, irrespective of whether there is flow present or not.
What cell culture applications would this device best suit?
This device would be best suited to any type of long-term dynamic cell culture where continuous monitoring is not possible. This would include any type of regulated flow stem cell cultures, microfluidic spheroid cultures, continuous flow blood vessel on a chip devices where continuous unidirectional shear stress is required, etc. The real-time response of these sensors would be especially beneficial where there is a possibility of biofouling, debris accumulation, or gradual blocking of channels, potentially altering flow rates.
