EYE on NPI – Sensirion SFM3119 Low-Pressure Drop Flow Meter

This week's EYE ON NPI is going with the flow and keepin' everything chill and low pressure with Sensirion's SFM3119 Low-Pressure Drop Flow Meter! (https://www.digikey.com/en/product-highlight/s/sensirion/sfm3119-low-pressure-drop-flow-meter) This sensor is designed primarily for medical use cases - ventilators, CPAPs, oxygen masks, etc., but could also be used for industrial setups where non-toxic gas flow needs to be measured. What's interesting about this sensor is it doesn't use a little fan like the turbine sensors (https://www.adafruit.com/product/5066) we've used before for liquid flow measurements. Instead there's a digital (capacitive?) flow sensor that does not impede gas/air flow. This means it can be used for very low flow rates without interference. Like many of the sensors we've been investigating lately, there's an integrated analog front end with I2C controller already inside, so no complex calibration or linearization setup is required. There's a simple 4 pin interface with power, ground, SCL and SDA. On GitHub we found a wide range of libraries (https://github.com/Sensirion/?q=sfm&type=all&language=&sort=) for Arduino, Python, and embedded C, to handle the various I2C commands and checksums required. Data comes out of the libraries as flow rate in slm (standard liter per minute) and temperature. We were able to get our Arduino example with OLED output display working within a few minutes! Given the strong support, low price, and ease-of-use we can recommend this flow rate sensor even for non-medical purposes. While its designed for air or oxygen, it could possibly be calibrated for other non-corrosive gas types. While we were prepping for this EYE ON NPI, the sensor went out of stock at Digi-Key! But according to the lead time estimate system, more Sensirion SFM3119's will be in stock at Digi-Key in the next month or two (https://www.digikey.com/short/2jcff3qp). You can back-order this sensor or sign up to be emailed when they come back into stock for immediate shipment or notification when the next batch of this popular sensor lands in the Digi-Key warehouse!