Thermal conductivity

Identifying a liquid or a mixture (for example by determining the thermal conductivity) is important in microfluidics for a variety of reasons:

The performance of a micropump is viscosity dependent.
An exact degree of mixing of two liquids should be controlled.
The whole process depends on the fluid currently used.

The ability to switch between fluids fairly easily and still allow the system to function optimally opens up a wide variety of applications for the microfluidic system.

Watch the thermal conductivity video to see the full experiment. You can also find more details in the case study.

Video: Determining thermal conductivity

The identification of the fluid in a microfluidic system is very important. Hence, our partner Sensirion has been working on an in-line and in-situ solution. Their thermal conductivity sensor is easily integrated in our system.

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The sensor measures the thermal conductivity of the fluid in the system. That allows you to identify the fluid and its viscosity. With this knowledge, you can then set the perfect frequency for the optimal flow rate.

You do not need a separate sample to measure the thermal conductivity. Therefore, this is an extremely efficient system. Additionally, you can also identify the mixing ratio of the fluid. Simply add this sensor to your system and you will have all the information you need in the software you use to control the system anyway.

Case Study: Identifying liquids and mixtures

Diaphragm-based micropumps such as the mp6 micropump can be controlled by the frequency (how often per second the diaphragm is actuated) and the control voltage of the actuating elements (control of the diaphragm stroke). Both parameters must be adjusted to the viscosity of the fluid and the desired flow rate. Especially in applications where different fluids are pumped by the same pump, it is useful to automate this manual step.

To this end, this case study shows that our mp6 micropump, in conjunction with Sensirion’s SLF3C-1300F sensor can detect the fluid thanks to thermal conductivity. Therefore, it creates the possibility to automate the pump parameter setting.