Maria Montero

Make Your Own Home Brewing Sensor Kit …

Have a party in the next few weeks where you want to do a little extra on fashion? Try making your own extra special beer with Gentleman Maker’s SmartBrewer! Make sure you have an Adafruit IO account ready to go and your Particle Photon on hand.

With the holidays just around the corner, it’s time to start thinking about parties! And with most parties comes some form of alcohol, be it an eggnog or a good pint of beer. But for some connoisseurs, store-bought beer is not enough, or just not feasible. That is why many people turn to home brewing!

Typical brewing systems include a bucket, a few ingredients, and a bit of patience, but for an engineer like me, that’s not enough! We want to know exactly what is going on with our beer at all times. In this project, we will create the SmartBrewer, which will allow us to monitor our delicious lager as it brews, just in time for next month’s party!

SmartBrewer BOM

The schematic

Take a look at Scheme-It for the full SmartBrewer schematic.

How does it work

The SmartBrewer consists of several sensors that allow us drinkers to see different readings about our beer. In our circuit, we measure the following:

  • Internal atmospheric pressure
  • Hydrometer level
  • Internal air temperature
  • Internal humidity
  • Internal alcohol vapor content

Internal pressure

The internal air pressure is recorded using the Adafruit MPL115A2 barometric pressure sensor. Recording pressure is important for three reasons:

  • Determine if there is a risk of contamination.
  • preventing oxygen from entering
  • observing the pressure of the brewery

When making alcohol, it is imperative that no contaminants, such as dust and insects, enter the container. Otherwise, the beer can go bad.

To prevent the ingress of external contaminants, an airlock can be used, which consists of a U-bend filled with water. This allows the pressurized gas to exit the container, but does not allow anything from the outside to enter inside. However, one of my last preparations was ruined because the container itself was not airtight, which could have ruined the batch. Oxygen should be kept away from brewing vessels, as oxygen allows a special bacteria, acetobacter, to convert alcohol into vinegar.

Brewing vessels are also at risk of exploding, in case vents and valves are blocked, the pressure sensor can warn us before that happens!

The hydrometer configuration with a magnet attached to the top.


To determine the amount of alcohol in an infusion (which is also an indicator of when it is ready to drink), a hydrometer is used. A hydrometer is a special glass vile with a scale printed on the side that will float at a specific level, and this level indicates the specific gravity.

Most hydrometers are analog and require manual reading. We need to be able to read it without opening the container. To achieve this, we will place a small magnet on top of the hydrometer and then we will have a magnetic sensor on top of the hydrometer. As the sugar and alcohol content change, the depth of float of the hydrometers will change, and this will result in a difference in height above the fluid. Therefore, the position of the magnet will change, and this will be measured with a magnetic sensor.

Temperature and humidity

While temperature is important (since fermentation occurs in a short temperature range), humidity is not. However, as this is a sensor project, I thought it would be interesting to measure as many things as possible, including humidity. It could turn out that moisture has an effect on the final product. This could mean that future breweries may have humidity control!