Weighing scale made out of a PCB

Electronics

Oct 17

In this project, I wanted to try something new and fun. First, I wanted to know if I can use the traces in the same way as a strain gauge. - The answer is no.

I created a similar pattern on the copper layer as the pattern on the strain gauges. However, the traces are made of pure copper (very good conductor) whereas the strain gauges are typically made of constantan (1 order of magnitude worse conductor). Thus, the trace pattern I created had a very low resistance (~1.1 Ohm, instead of 350 Ohm) and the change in its resistance upon deformation was even lower, nearly undetectable. Therefore I ditched the idea of using the traces for measuring the deflection of the PCB. But, I had this potential issue in mind when I created the circuit board, so I was able to easily attach a strain gauge to the cantilever part of the PCB. Luckily, this saved the whole circuit, it worked as expected.

This project is more of a prototype project. It allowed me to see if I can use the PCB as a load cell, and the conclusion is: yes! This will open up a lot of fun applications of PCBs.