Water Sensors
Applied Impact Robotics - Engineering Intern - Summer 2025
Purpose
The robot will perform tests in several different environments prior to a crude oil tank, beginning with water. Electronics are stored all over the robot, so it’s important that preventing water from reaching those electronics is critical. It is for this reason that some of the sections of the robot are filled with mineral oil. It is also critical that there is water detection using sensors.
OTS Sensor Testing
I started out by testing two water sensors’ sensitivity. One had digital and analog output (black), and the other has only analog output (red).
I first tested how many drops of water was required until the sensor detected moisture. For both, the analog output detected water immediately, which was expected. However, for the black sensor, the digital output had exhibited a higher tolerance, which was also anticipated. Once I did a few trials and recorded the data, I moved onto submerging the sensors in mineral oil, and then dropping water right over them. As expected, it took significantly longer for water to be detected because the mineral oil created a hydrophobic film over the sensors’ surfaces.
Simple Water Sensors
While the OTS water sensors functioned, they real estate in the robot is expensive, so smaller sensors were needed. Luckily, water sensors function using two exposed leads, and react when submerged in water because it completes the circuit. So, it was really easy to make a few designs. I needed to test circular, straight-line, and rectangular sensors. It was easy to model in Onshape—just make a base, a channel for wire to sit in, and a few ‘caps’ to prevent the wire from popping out.
Results
After performing water tests with the sensors by hooking them up to a PCB, I was able to read their analog signals, proving their viability as a water detection method.
