Hardware

You will need the following parts for this project:

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eTape Liquid Level Sensor

Make sure to get the food safe sensor if you're mixing liquids for people to consume.

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Arduino YunArduino Uno, or other microcontroller with an analog input.

If you use the Yun you can make a web page which displays the measured liquid volume.

If you use the Uno or other microcontroller you'll want to add a display, like one of these OLED graphic displays.

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Female to male hookup wires.  These will connect the sensor to the Arduino.

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Graduated cylinder or other container to hold liquids.  For the 12" liquid sensor a 500ml graduated cylinder is the perfect size.

The container should be tall enough to hold the entire liquid sensor without bending, and it should have a constant size so the volume can be calculated.

Make sure to use a container which is food safe plastic or glass if measuring liquid for people to consume.

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MicroSD card for storing scripts and data on the Arduino Yun.  Any card with about 10-20 megabytes of free space should work.

Assembly

The assembly of the hardware is very simple because the eTape liquid sensor is a resistive sensor, just like a photocell. Attach one of the middle two leads to ground on the Arduino. Attach the other middle lead to an analog input such as analog 0 on the Arduino. Finally attach the 560 ohm resistor that comes with the sensor between the analog 0 and 5 volt pins on the Arduino.

The outer two pins on the sensor will be unused (they're for temperature compensation in a bridge configuration).

You can see a diagram and photo of the wiring below:
To attach the liquid sensor to a container, place the sensor against a wall of the container. Make sure the sensor hangs vertically with no bends or crimps. Only the top portion of the sensor above the MAX line can be attached to the container. The rest of the sensor must be allowed to hang freely so liquid can touch both the front and back of the sensor. Check the sensor datasheet if you need more information about using or mounting the sensor.

Below you can see how I attached the sensor to a graduated cylinder with a binder clip. This clip works well as a temporary means of affixing the sensor. For something more permanent consider taping or gluing the top of the sensor to the container (remember only glue or tape the sensor above the MAX line!). Use a food safe adhesive such as silicone sealant if necessary.

You can also see I bent the wires in a tall loop and taped them onto the back of the cylinder as a strain relief.
This guide was first published on Apr 14, 2014. It was last updated on Apr 14, 2014. This page (Hardware) was last updated on Jun 24, 2019.