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Flusso publishes FLS110 packaging innovations

Flusso has published first details of some packaging design innovations that have been specifically developed for use in the FLS110, the world’s smallest flow sensor.

The new features have been designed to maintain high performance of the FLS110 flow sensor across a wide range of flows, while reducing its overall size and cost for use in mass-market applications.

The details are discussed in a research paper entitled ‘On the Design of the World’s Smallest Flow Sensor Package’. The paper has been written by four members of Flusso’s in-house engineering team in collaboration with Dr John Coull from University of Oxford, and published in the peer-reviewed journal IEEE Sensors Letters (Volume 5, Issue 6, June 2021).

When it comes to flow sensors, the package is responsible for directing the air flow across the thermal flow sensing components and is a critical factor in determining its performance. The design of the package lid is vital for controlling the behaviour of that flow, and even more so in the FLS110 which has a footprint of just 3.5 by 3.5 mm.

News thumbnail packaging paper
This 3D render shows a package cutaway of one investigated design where flow guiding structures are being used. The thermal flow sensing components are shown in green.
News page packaging paper
These velocity magnitude isolines show how vortex guides can be used to control and divert the vortices away from the central sensing region.

Although several companies have developed specific packaging features to feed and smooth the air flow into a thin channel for measurement, none of them could be used within the FLS110 because it is so small. The FLS110 is 70% smaller than what was previously the world’s smallest mass flow sensor.

The transition from a circular inlet port on the package lid to a rectangular sensing channel through a 90 degree bend leads to the formation of vortices, which can interact with each other along the sensing channel and impact the sensor’s performance. To overcome this, Flusso has developed a novel approach using ‘vortex guides’. These structures ensure the flow along the sensing channel is much more uniform by controlling and diverting the vortices away from the sensing region.

Flusso has further developed and optimised the flow guiding structures referred to in its research paper and has now integrated them into the FLS110 flow sensor that was launched last year. The company has secured a number of patents based on its packaging innovations, which can also be easily implemented at low-cost in flow sensors that are even smaller than the FLS110.

Read the paper abstract.

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