IR liquid level sensing with Arduino

January 31, 2017 // By Graham Prophet
SST Sensing and Sparkfun, have developed and simple to implement solution for single point liquid detection using infra-red technology, using an Optomax Digital liquid level switch which is connected to an Arduino board via the TTL output and powered by its 5V source.


LEDs on the Arduino can be programmed to indicate if the sensor is/isn’t immersed by the liquid (and thus determine if liquid level is too high/low). The two companies say that the hardware provides scope for experimenters hobbyists are provided with plenty of scope to experiment, while professional engineers have the opportunity to evaluate their prototype before moving on to a full scale design.


The Optomax devices have compact dimensions that allow them to be deployed within environments where there is only limited available space. As relatively long cabling can be supported, the sensor can be placed in close proximity to a liquid without any risk of the accompanying electronics on the Arduino being damaged. As this solution is optical rather than mechanical nature, issues such as the build-up of deposits, jamming, or wear and tear are avoided. A long term operational life span is thereby assured.


The liquid level switch can be supplied by SST in a robust housing with either a Polysulfone or Trogamid construction (depending on the particular application requirements). The complete solution has an operational temperature range that covers -25°C to +80°C.




The SST Liquid Level Sensor provides single point liquid detection via a TTL compatible push/pull output. An infra-red LED and phototransistor accurately positioned at the base of the sensing tip ensure good optical coupling between the two when the sensor is in air. When the sensing tip is immersed in liquid, the infra-red light escapes from the cone, causing a change in the amount of light present at the phototransistor, which makes the output change state.


SST Sensing;