University of Cambridge spin-out Flusso has launched what it claims to be “the world’s smallest flow sensor” – with a 3.5 x 3.5mm footprint.

Flusso-FLS110-flow-sensor

Called FLS110, it is a CMOS device designed for gas flow measurements, with gas entering and leaving through two  tubular stubs.

Flow range is up to 200cm3/min directly through the sensor, or from 0.001 to >500litre/min used in a bypass arrangement (above diagram). Measurements are temperature-compensated, and operation is across -20 to +85°C (ambient and gas).

Flusso flow sensorRepeatability is said to be 0.5cm3/min +0.5% of measured value, and it comes in a reflow solderable six-pin DFN.

Inside, the sensor works in the same way as a hot wire anemometer – gas flow is estimated from its cooling effect on a hot surface – with micro-heater and temperature sensor integrated in a MEMS die.

Interfaces are analogue, and a microcontroller is required to drive the sensor and read its results.

Flusso is providing suitable firmware – it currently lists STM32 as a host microcontroller in its short-form data sheet.

Flusso-16mm-bypass100 litre/min bypass accessory (126 x 18 x 26mm, tubes are 16mm dia outside)

Applications are foreseen in vacuum cleaner filter monitoring, air-conditioning units, pipe blockage detection (particularly in gas detectors), air pump monitoring, air pump control, portable healthcare equipment (inhalers) and fitness monitoring masks.

“Flow measurement is often seen as being a difficult and time-consuming function to implement, requiring specialist engineering expertise and know-how,” according to Flusso. “Flusso has taken a different approach and developed its customisable flow sensing solution to integrate hardware and software with mechanical and fluidic components.”

Flusso flow sensor eval kitSamples are available now, within a product evaluation kit (left). Volume production is scheduled for the first half of 2021.

Flusso was spun-out of The University of Cambridge in 2016 to exploit technology developed by the high voltage microelectronics and sensors group at the electrical engineering department.

It has an in-house team of scientists, engineers and semiconductor industry professionals, and raised $5.7m in a Series A round.