Typical areas of application for microfluidics

Microfluidics refers to the manipulation of small quantities of fluids, often in the range of micro- and nanoliters, in tiny channels and structures. This technology is used in various fields of application.

• Analytics and diagnostics:

Microfluidics is often used in lab-on-a-chip systems to analyze samples in small volumes.

Rapid diagnosis of diseases, detection of biomarkers and genetic analysis are typical applications.

• Medical applications:

The development of miniaturized drug delivery systems, including implantable micropumps.

Lab-on-a-chip technologies for point-of-care diagnostics and disease monitoring.

• Chemical synthesis and reactions:

Carrying out chemical reactions in small volumes, which leads to faster reaction times and more precise results.

Optimization of synthesis processes and production of nanomaterials.

• Environmental monitoring:

Miniaturized sensors for monitoring environmental parameters such as water quality, air pollution and soil analysis.

In-situ analysis of environmental samples.

• Food and beverage industry:

Control of processes in food production, such as mixing, dosing and filling.

Rapid analysis of food samples for quality control.

• Biotechnology:

Cell manipulation, cell sorting and analysis of individual cells.

Research into protein folding and gene expression at the level of individual molecules.

• Pharmaceuticals:

Development of miniaturized devices for high-throughput drug screening.

Improvement of drug delivery systems.

• Optofluidics:

Integration of optical components with microfluidic systems for applications in optical signal processing and sensor technology.

• Energy:

Microfluidic systems are used in fuel cells and batteries to improve efficiency.

Cooling of electronic devices through microchannels for better heat dissipation.

• Research and development:

Microfluidics is used in laboratories for researching new technologies and developing prototypes.

Analysis of soil outcrops in the compartmentalized flow

The so-called segmented flow is one of the wonderful tools in the microfluidic toolbox. This flow is generated in micro-reactors featuring channels with a diameter of 100 to 200 µm. A polar liquid (water) is introduced to an intersection point of a nonpolar carrier flow (oil). Since the two liquids will not mix, individual water droplets will be torn away and join the oil flow. The droplet sizes are very defined and constant and they happen at defined intervals, while being separated from each other by the oil between them.

Large amounts of these droplets can be created in a very short time. If the soil concentration in the water is correct, each droplet contains just one individual or very few organisms, existing in their own habitat, where they can procreate and form cultures. Arranged on a coil of narrow tubing, similar to beads on a pearl necklace, they can now be taken to an incubator offering the appropriate growing environment.

Generating such small, defined and segmented flows requires highly precise, pulsation-free and controllable pumps, such as the CETONI Nemesys S. Thanks to its excellent dosing properties, substances, such as nutrients, can be dosed into the individual droplets. Also, it is possible to detect clouding and separate promising droplets. The CETONI Elements software allows users to operate the system comfortably and intuitively.

 

Bio-printing and pulsation-free flow

For the successful printing of biomaterials such as cells and tissues with their extremely difficult structures, precise fluid dosing is just as necessary as an even supply of the print head. Only in this way is it possible to create homogenous layers with a high degree of reproducibility. Our Nemesys S syringe pumps Due to their precision and particularly even feed of the medium, they are perfect for applications in this area and thanks to autoclavable ones Glass syringes contamination and cleanability are also not a challenge.

Simply put together a setup from several syringe pumps and couple it with an XYZ positioning system via our CETONI Elements software – Your universal bioprinting station is ready!

Geochemistry – High Pressure Syringe Pumps used in Crude Oil Research

The global demand for oil is increasing from year to year, at the same time we know that oil is a limited, non-renewable resource. Therefore, the search for methods enabling an improved exploitation of existing reservoirs and the related research has started some years ago. After all, the “black gold” is rarely found in underground caverns, but embedded in rocks. The physical and chemical properties of these rocks and the oil contained in them vary from location to location. In order to extract the oil, bore holes are filled with gas or liquids. Chemical (tensides) and physical methods (temperature), and even micro-organisms are employed in this process. The goal is to lower the oil’s viscosity and the surface tension between oil and rock, and doing it in a targeted manner, in order to extract as much oil as possible.

EOR

All of these methods are referred to as tertiary exploration or enhanced oil recovery (EOR). Since this type of research requires a precise simulation of storage and extraction conditions, the use of CETONI high-pressure syringe pumps makes sense. Many companies and institutes all over the world already use CETONI equipment in this field and have achieved and published promising research results.

Once the oil is at the surface, it becomes clear that there are different types of oil. Due to different compositions and rheological properties, products from different reservoirs have to be analyzed and characterized at regular intervals. The crude oil’s composition decides which products and which quantities can be made from a certain quantity of crude (e.g. a barrel). This has an effect on the price that can be achieved with this product and the profitability of the respective bore hole. The rheological properties, meaning the deformation and flow properties of the crude oil, influence the extraction speed and the maximum degree of exploitation for a particular reservoir. This, in turn, is a critical factor in the profitability of oil extraction as well as the availability of this desperately needed resource.

pVT

An important method for both – composition and rheological properties – is the pVT analysis. In this process, a specific amount of the sample at a specific temperature is pushed through a capillary of defined diameter and length. As the liquid passes through the capillary, the pressure loss is measures. If this measurement is taken at various temperatures, one receives a whole grid of the sample’s important physical properties. The accuracy of the measured data is governed by the parameters set during the analysis. High pressure syringe pumps from CETONI are therefore preferably used for such measurements with pVT cells, as they convey precise and pulsation-free volume flows even at pressures of several hundred bar, as well as simply adding functions such as pressure measurement or syringe heaters can be expanded.

Precision Dosing for Special Applications

The use of micro-fluidic processes is not limited to research labs. Industrial companies are already successfully using CETONI Flow-systems for the precision dosing of fluids. The bandwidth of application is enormous and ranges from model solutions to large-scale and automated systems.

Varnishes, Lubricants and Adhesives

The application of finishes requires a jerk-free media supply system. Our high-precision syringe pumps are capable of dosing without pulsation and at high precision down into the nano-liter range, therefore providing a homogenous coating process. A media supply that is interruption-free and independent from the syringe volume is made possible by combining our special valves with our innovative QmixElements control and automation software, which smoothly blends the operation of alternating syringe pumps during continuous media transport.

Thanks to its modular design and the available interfaces, the dosing system can be easily expanded and integrated into existing coating systems. In addition, its operation is simple and allows for efficient processes, thanks to the ability to exchange syringes very fast instead of employing complex rinsing and cleaning procedures.

Flow Chemistry

Flow chemistry is becoming increasingly interesting with regard to the implementation of industrial processes. Requiring only small quantities of poisonous or highly sensitive substances makes an important contribution toward achieving improved process safety and control. This simplifies the control of endothermic and exothermic processes as well as elevating temperatures beyond the boiling point with regard to critical reactions. The miniaturization of processes increases efficiency, while lowering costs at the same time. Even scaling up a proven reaction becomes quick and easy.

Particle Synthesis

Particle synthesis requires a setup providing extremely precise fluid dosing at very continuous flowrates. A media supply that is uninterruptable and independent from the syringe volume (continuous flow) is made possible by our innovative QmixElements control and automation software. By using an intelligent algorithm, it ensures the smooth blending of alternating syringe pumps during continuous media transport, to a point where it becomes practically unnoticeable. Thanks to the ability to choose from various different material combinations with regard to the medium-affected components, the fluid system is resistant to many different chemicals. Also, it makes no difference whether the system is operated under normal atmospheric conditions or high pressure. The neMESYS technology fulfills both requirements with excellent results.

Complex Systems and Integration

Apart from compact setups, our modules can also be used to realize highly complex systems, that feature pressure and temperature control or could be fitted with sample handling components, such as our rotAXYS system or additional analysis modules. In addition, they can be automated using our comprehensive QmixElements controlling software.

Microfluidics for analytical processes

Rapid advances in micro-fluidics led to the development of highly efficient chemical analytic processes. The miniaturization of fluid analysis makes it possible to work effectively with small reaction volumes and therefore places high demands on the hard and software components being used, particularly regarding precision and versatility.

Fluid Chromatography

Fluid chromatography processes, such as HPLC, require continuous fluid streams without pulsation, as well as media-resistant systems that are able to provide high pressure and can be cleaned quickly and easily. The highly flexible syringe pump systems of the Nemesys range, fulfill these requirements and are therefore the ideal alternative to conventional HPLC-pumps. From automated sample feeding and preparation or fraction collection by means of collaborating laboratory robots (Cobomation), to high-precision conveying by Nemesys syringe pumps and analysis by integrated spectrometers, CETONI offers an all-encompassing approach that can be easily expanded thanks to its modular design.

Requirements, such as the fast and hard adjustment of solvent ratios, medium change or the ability to transport larger volumes do not pose a problem for the dosing system. Beyond that, the analysis process can be easily automated, using our powerful CETONI Elements control software.

Flow Cytometry

Flow cytometry is a powerful analytic method for the precise determination and characterization of particles, such as cells, spores and blood samples. Depending on their application, these analytic processes often happen at moderate system pressure levels. An essential requirement for the success of these sensitive processes is a highly continuous stream of analytes, such as individual cells, for example.

The pulsation-free character and the superior precision of Nemesys syringe pump drives is therefore ideal for analytic processes in the sub-microliter range. The combination and synchronization with periphery devices, such as laboratory cameras, can be interesting for the continuous detection of cells in a fluid stream. A space saving, modular and expandable system is a big asset in this case. Of course, the increasing number of devices and the increasing complexity of applications also leads to higher demands regarding the operation and synchronization of all components involved. Our powerful and user-friendly CETONI Elements software is the answer to all of your automation needs and gives you more room for creativity.

CETONI Elements now supports precision scales!

Integration of a high-resolution precision balance in your application offers you precise information at every point in your process and thus additional security. With the help of our flexible laboratory automation software CETONI Elements You can now integrate precision scales into your process and use them for targeted control of your high-precision dosing, automation of processes or permanent process monitoring.

Simply install the latest QmixElements update and getting started!

The CETONI Elements software now supports the integration of laboratory balances via the balance plug-in. A device driver for Sartorius scales (Entris, ED, GK and GW scales) is already included with the release of the plugin. This means that you can easily integrate your existing Sartorius laboratory balance into the CETONI Elements software. Thus you not only extend your CETONI system with the possibility to weigh substances, substances or dosed liquids, but you can also synchronise or completely automate processes as you wish in interaction with other CETONI hardware and your own analysis.

CETONI Elements with two Nemesys syringe pumps and a scale

The configuration of the scale devices is carried out, as you are used to from the CETONI Elements software, via the device configurator. Simply create a new configuration or add the scale to an existing configuration and save it. After activating the configuration, the scale is available in the software.

Elements Device Configurator

In the software, the scale is then displayed as a normal analogue input channel in the list of I/O channels ❶. There you can see the current value at any time and tare the scale via the context menu of the channel. Like all other analogue channels, you can also record this channel in the graphic logger ❷ or in the CSV logger and use it to create control channels. Due to the real-time recording of the measured value in the graphic logger, dynamic weight changes, e.g. when dosing into a sample vessel, can be visualised and followed very well.

List of I/O channels with scale channel

The measuring channel of the scale can be read via the script system and taring of the scale is also possible via a script function. This allows the scale to be easily integrated into more complex analyses and automated processes.

Cell-on-Chip: More and more research fields aim to miniaturize and transfer cell cultures and complete assays to a lab-on-a-chip system. On the one hand, the reduced analysis areas mean that less sample is required, and on the other hand, it is possible to observe cell behaviour in real time. High-precision and pulsation-free dosing systems are the key to successful implementation of such lab-on-a-chip procedures. Our CETONI nemesys syringe pumps are used in numerous laboratories for the realization of microfluidic analyses.

We have therefore compiled 10 tips from which beginners and experienced researchers can benefit in their work.

1. The right chip material

The demands on the chip material for cell cultivation are high. The material should not only be biocompatible, but also have a high transmission property. For this reason, most of the work is based on the polymers PDMS (polydimethylsiloxane) or COC (cycloolefin copolymers). Nevertheless, PDMS also has some disadvantages due to its gas permeability and it is not resistant to chemicals, which means that COC or glass are becoming more and more important.

2. CO2-independent cell culture media

CO2-independent media are ready-to-use formulations which independently build up HEPES-(2-(4-(2-hydroxyethyl)-1-piperazinyl)-ethanesulfonic acid)- a buffer system, e.g. based on mono- and di-basic sodium phosphate and β-glycerophosphate. Therefore, the supply of CO2 is not necessary to maintain the buffer system.

3. Separated cell reservoirs

The use of cavities (lowered cell reservoirs) can both create a microclimate within the cell reservoir and protect the cells from shear stress, both of which are otherwise disadvantages of flow cell cultivation.

4. Coating favours cell adhesion

Many different wet chemical coating substances are known to promote cell adhesion. Collagen, gelatine or the substance mixture Matrigel® are most commonly used. Depending on the cell culture used, the suitability must be investigated on the basis of a time-dependent growth profile.

5. Exact control of the flow

A too high flow rate can not only prevent the adhesion of the cells, but can even detach them, both of which are a consequence of the shear stress that is too high in this case. A flow rate that is too low, on the other hand, would not mean a sufficient supply of nutrients for the cells. Ultimately, a compromise must be chosen in which the flow rate is adapted to the glucose consumption of the cells.

6. Constant temperatures

Miniaturized cell-based sensors allow the holistic statement on cell physiological processes in real time through incubator-independent observation. However, this requires the maintenance of 37 °C for the cultivation of human cells. In this respect, different approaches are taken when heating an incubator-independent system. Peltier elements, heating foils or slides, which have been provided with an ITO (Indium Tin Oxide) coating. The ITO coating offers an even temperature distribution and an excellent optical transparency for simultaneous light microscopic examinations of the cell culture.

7. Eliminating gas bubbles

In addition to the general aim of air-free filling of the system, the greatest challenge in microfluidics is to reduce remaining gas bubbles in the chip system. Very often media are degassed beforehand or so-called “bubble traps” (degasser) are used in the process. These not only represent an expense in terms of equipment and a potential risk of contamination, but also make pulsation-free conveying more difficult. Another approach makes use of Henry’s law, where the proportion of gas dissolved in a liquid is proportional to the pressure. In a figurative sense, the increase in pressure in the system favours the solubility of the smallest gas bubbles in the system, which thus lose their disturbing effect. This effect can be exploited by the correct placement of a back-pressure regulator (BPR), which provides a fluidic resistance and thus ensures the desired pressure increase depending on the set flow rate.

8. Continuous-flow

In order to expose cells to conditions as homogeneous as possible and to supply them continuously with nutrients, a continuous and low-pulsating flow is essential. Subsequent incubation with appropriate test substances allows meaningful and reproducible results to be generated afterwards.

9. Reduce the risk of contamination

A contaminated cell culture is a nightmare for every cell researcher. Especially in incubator-independent cell-on-chip research, the risk of contamination is correspondingly high and should be monitored particularly carefully. The use of special sterile filters before and after the chip system supports contamination-free cultivation. Special attention should of course be paid to the fluid connection technology and the conveyor system. Through the targeted use of disposable or autoclavable components such as syringes and valves, the modular nemesys syringe pumps are ideally suited for this purpose.

10. The cell seeding

The cell seeding process in the chip system is particularly critical because the uniform cell distribution has a decisive influence on the validity of the experiment. The introduction of the cells into a fully assembled microfluidic system requires either some fingertip sensitivity or constructive mechanisms that ensure an even cell distribution. The following methods for cell trapping can be distinguished: hydrodynamic, optical, magnetic, electrical or acoustic.

In their latest publication, a team from the laboratory of Mohammad A. Qasaimeh, at New York University Abu Dhabi, set a new milestone for open space microfluidics in the field of cell biology. The researchers developed a new kind of open-space microfluidic system for the sequential cell separation and patterning based on dielectrophoresis, and are able to reach a cell purity of ~90 %.

The syringe pumps were used to generate flow from the injection to aspiration aperture of their device, in order to generate a hydrodynamic flow confinement within which cell separation occurred.

Laboratory Setup:

For the research work it was necessary to use specially developed and 3D-printed microfluidic chips. Based on the Hele-Shaw-cell approximation, the flow was generated between two parallel flat plates by simultaneous injection and aspiration of fluids from the microelectrofluidic probe. Dielectrophoresis forces were then used to isolate target cells out of the flow stream and sequentially pattern them on the bottom substrate. Based on this method, cell purity of up to ~90 % was reached, characterized by fluorescence microscopy.

With their publication in Lab on a Chip last year, Qasaimeh et al. provide new tools to separate specific cells from heterogeneous cell population without need of any microchannels and have thus laid important foundations for this field of research.

Laboratory setup cell separation

The setup for the investigation of open space microfluidics for cell separation could be realized with a modular and high-precision CETONI dosing system. In order to generate continuous multipoles to separate cells with a high isolation efficiency, an extremely uniform and pulsation-free fluid flow is required. The nemesys precision syringe pumps are ideally suited for precise and smooth dosing of smallest fluid quantities. Thanks to its modularity, the setup can also be extended at any time, giving the research team complete flexibility in their work.

Used CETONI devices:

• Base 120
• 6x CETONI nemesys Low Pressure Syringe Pumps 290N

Literature:
A. T. Brimmo, A. Menacherya, M. A. Qasaimeh: Microelectrofluidic probe for sequential cell separation and patterning. 2019, (19), 4052-4063. DOI: 10.1039/C9LC00748B

In the second part of this tutorial you will learn how to create sinusoidal flow profiles using JavaScript functions. To do this, you modify the script from the first part so that a sinusoidal profile is generated instead of a sawtooth profile. Before you start with this second part, you may want to read the first part of the tutorial here.

Important
For this tutorial, you need QmixElements version v20191121 or a newer version. If you are still using an older version, please update to the latest QmixElements version.

Latest QmixElements Version

Preparation

Configure your system as described in the first part of the tutorial and then connect to your devices. If you do not have the appropriate devices, you are welcome to follow the tutorial with simulated devices. The QmixElements project with simulated devices and the script created in the first tutorial can be downloaded here.

Now open the script Tutorial_Sawtooth_Profile.qsc that you created in the first part of the tutorial and save it under a new name. You should then see the following program in script editor.

Part 2 – Script for generating a sinusoidal profile

The goal of this script is to generate a flow profile in the form of a sine wave from 0 to the defined target flow rate with one pump and to supplement the flow of the first pump with the second pump in such a way that the sum of the two flows results in a constant flow with a defined flow rate.

To generate the profile, the flow rate of the pump must be changed step by step so that a sinusoidal profile is created over time. The number of steps for generating the sine profile, i.e. the resolution, should be set to 100 steps for one sine. In the previous sawtooth script you had set the number of steps to 20. Therefore change the value of the variable $GradientSteps to 100.

Adjusting the resolution (number of steps) for a sine profile

Now delete the two Generate Flow functions as shown in the figure below. To do this, select both functions and then delete them using the context menu (right mouse button) or by pressing the Delete key.

Now insert a new variable before the two existing variables in the counting loop. Name the variable $Sinus and select JavaScript Expression in the Type field.

The $Sine variable is used to store the calculation of the sine value for further processing. To calculate the sine value, use the JavaScript function Math.sin() together with the constant Math.PI. Enter the following into the input field for the JavaScript expression:

Math.sin(2 * Math.PI / ($GradientSteps – 1) * $i)

The loop counter $i runs from 0 to the number of $GradientSteps – 1. To calculate the current sine value, the period 2π is divided by the number of steps – 1 and then multiplied by the current step $i.

To check the calculated value of the $Sine variable, you can display its value in the graphical logger. To do this, you have already created the virtual I/O channel Script Value 1 in the first part of the tutorial and added it to the graphical logger. Now insert the function Write Device Property ❶ into the script. Then configure the function as shown in the figure below.

In the field Value to be written ❷ enter the variable name $Sinus. In the Device Property area ❸ select in the Devicefield the virtual channel Script Value 1. In the Property field select the property ActualValue. You can now read the function as follows:

Write the value of the variable $Sinus into the property ActualValue of the virtual channel Script Value 1.

Now delete all data from the graphical logger and activate automatic scaling. Now start your script. If you have entered everything correctly, you should see how the following sine function is generated in the graphical logger:

The sine oscillates between 1 and -1 as expected. For the sinusoidal flow profile to be generated, the flow rate should oscillate between 0 and the target flow rate. In a first step, the sine value should be adjusted so that it oscillates between 0 and 1. You can achieve this by shifting the sine on the Y-axis upwards by 1 and then halve the amplitude. To store the new value, we use the existing variable $Flow1 ❶. This can now be calculated like this:

❷ $Flow1 = ($Sine + 1) / 2

Now change the Write Device Property function so that the value of the variable $Flow1 is displayed instead of the value of the variable $Sine. Then delete the graphical logger and reactivate automatic scaling. You should now see the following function in the graphic logger – a sine function oscillating between 0 and 1:

To make the sine oscillate between 0 and the target flow rate, you now only have to multiply by the target flow rate $TargetFlow. Extend the calculation of the variable $Flow1 by this step:

$Flow1 = ($Sine + 1) / 2 * $TargetFlow

The flow rate $Flow1 will now oscillate sinusoidally between 0 and the target flow rate. The flow rate $Flow2 of the second pump should complement the first flow rate in such a way that a constant flow with a constant flow rate $TargetFlow is created. You can therefore calculate the flow rate of the second pump in the variable $Flow2 as follows:

$Flow2 = $TargetFlow – $Flow1

Now insert two Generate Flow functions in front of the Write Device Property function and then delete the Write Device Property function as it is no longer needed.

The script should now look like the figure below ❶. Configure the two Generate Flow functions to start the first pump at flow rate $Flow1 ❷ and the second pump at flow rate $Flow2 (see figure below). Make sure that the Run to completion option ❸ is disabled.

Now delete all data from the graphical logger again and activate automatic scaling. Before starting the script, check that the syringes of both pumps are filled. Then start your script. If you have entered everything correctly, you should see how the following flow profiles are generated in the graphical logger:

You have now learned the basics of how to use JavaScript in the script functions – e.g. to perform mathematical calculations. Apply what you have learned, for example by programming a script that generates two sinusoidal flows, where the sine of the second flow has twice the period of the sine of the first flow. Use the graphical logger to check the results.

In the third part of the tutorial you will learn how to add an initialization routine to the script, how to wind up the syringes and get tips on how to improve the readability of your script and how to document your script.

The QmixElements project with simulated devices and the scripts created in the first and second part of the tutorial can be downloaded here.

Nowadays, medical science needs to be more innovation-driven and personalized than ever. That’s why microfluidics play a critical role in researching new therapeutic approaches. CETONI has a clear mission: with innovative solutions, we not only empower our customers to be part of the development process, we even allow them to take charge.

Unlike conventional methods, individualized medicine focuses on humans instead of diseases. The primary goal is patient-oriented interventions without time loss or side effects. The establishment of in-vitro assays, as a first step toward authoritative effectiveness tests, has paved the way for developing personalized therapies in a way that is sensible and available to the masses.

Conventional processes are reaching their limits

Cell cultivation is usually done in standardized cell culture flasks in a regulated CO2 environment. The enclosed incubation unit maintains a constant temperature, high humidity and sterility. But there is a problem caused by spatial separation between cell cultures and the analysis unit, which makes it impossible to arrive at a holistic conclusion about the real-time physiological process inside the cells. Microfluidic systems, on the other hand, are perfectly suited to the simultaneous analysis of different test substances. Therefore, the development of an automated cell culture for the purpose of reducing costs and time-consuming tasks, as well as the real-time observation of cells, becomes very interesting, particularly with respect to developing personalized therapies.

After a short implementation phase, the miniaturization of laboratory processes, from standardized in-vitro assays in well designs to lab-on-a-chip systems, becomes extremely lucrative in terms of time and cost-savings. Due to the reduced analysis areas inside the chip, the required samples are very small. This technology offers new possibilities, particularly when it comes to cell cultivation. These systems can not only automate cell seeding and supply nutrients to the cell culture. They also allow for toxic stimulation of cells in real time. Since the cell culture areas are very small, only a small number of cells are needed, which can be analyzed in real time, while ensuring a controlled supply of cells through an automatic pump and supply system with a heating unit. In addition, the pump system allows for automated cultivation.