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What is responsiveness?

MFCS™ systems have been designed to control flows in microfluidic paths or systems. Responsiveness is their ability to provide a flow within the required time frame. This determines the ability of a microfluidic pump to reach a setting point. In order to better understand system responsiveness, three time factors must be distinguished.


The response time

 

The response time is the elapsed time between the sending of a command from the computer system and the beginning of a response. In microfluidics, response time is the duration between an inquiry and the the start of flow (the first reaction of the microfluidic pump).


The rising time

The rising time is the time a system takes to move from a starting value to a set value. However, it does not give any information about the fact that the set-point is reached. Some devices may have an excellent response time but also provide long transient states until flow is stable. This is typical of syringe pumps with particularly highly resistant systems.

In microfluidics, the rising time is the time elapsed to go from 10% to 90% (or sometimes 95%) of the setting flow-rate or pressure requested.


The settling time

The settling time is the elapsed time to get to and remain within a specified error margin of the final value. It gives information about how fast the system reaches the set-point in a stable way. The settling time includes the response time, plus the rising time and finally, the time needed to be within the specified error margin.

In microfluidics, the settling time is generally defined as the time needed for the response of flow to reach and remain within an error band of ±5% of the final value of the flow. This is a function of the delivery system as well as the fluidic system resistance.

When choosing a microfluidic instrument, one needs to not only look at the response time but also at the settling time to conduct the experiment at steady state as fast as desired. For these reasons, all of our MFCS™ systems have a short response time (down to 40ms or better depending on user computer OS) but they also offer a minimal settling time (flow path dependent to stay at a stable state.

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