Taidacent Strain Gauge 350 Ohm Bend Flex Sensor Weighing Amplifier Module Pressure Sensor Analog Output Strain Gauge Test Kit (Extension Cable)

I plan on using the strain gauge module as a load cell to accurately determine the amount of filament remaining on the reel for my 3D printer. I'll glue the strain gauge to a flexible lever arm and activate the module when the filament reaches a certain level to reduce the required dynamic range. I should be able to get it accurate to a few grams of available filament left on the reel. I will input the strain gauge module's output to an HX711 Load Cell Amplifier A/D and connect that output to an Arduino to process. The strain gauge module has a Wheatstone bridge followed by an amplifier to bring the voltage to a 5V range. Note that there are many 350 ohm strain gauge sensors available on Amazon that are similar to that which this module uses for less than a dollar per unit so experimenting is inexpensive.

Never could get this little gauge going - but I think it might have been my application. Pretty obvious connections and the output can be used directly into a little arduino with not too much drama. Should work ok for typical Arduino applications where you just need some fine-feedback for stuff ilke motor torque maximums or whatever. Wish I could have figured it out better, but it does seem to give some feedback. One star off because of lack of documentation for average users.

By default the potentiometer is set so that with the strain gauge unstressed the output is about 2.5V. Bending up or down by 30 degrees with change the voltage linearly to 5 and 0V respectively. I did not have a setup that would allow me to do controlled graphs of output vs amount of bend. I also did not look at the affects of temperature. One thing you can do is if you only need to know about flex in one direction you can adjust the pot to get get more range of motion in the direction you want to measure. Twisting the strain gage can affect you reading. If all you need is a touch sensor there are simpler solutions, but if you do need to know the relative amount of flex this may be a good solution for you.

At least at low supply voltage (4V), 10mV of supply noise was replicated on the output.

I already had a circuit that used a linear potentiometer, and I was able to drop this in as a replacement. When the strain gauge is bent down the resistance increases. When it is returned to flat or bent up, the resistance is low. The gauge itself is tiny and very sensitive. It is wired on a lead (as show in the description) that connects to a board that handles the reading of the gauge. There are three standard pins as with other pots; Vcc, Gnd and Output. If you have a project where you want to have touch sensitivity but not simply on or off, this can be the way to go.

Feets are a bit short, even with the extended version. But I'm making it work for my project. Which is a proof of concept and this is a cheap and great device to prove that out.

Works as expected on analog pins. Outputs are reasonably consistent (depends a lot on how you design the rest of the setup and interference from things like ceiling fans), but I found it's much easier to set triggers based on wide 100mV gaps rather than trying to get a precise numerical estimation of weight. It's also just fun to play around with.

I found it hard to get consistent results with this flex sensor... it was hard to find where it was sensitive to bending. However, with a bit of experimenting, it should be an interesting sensor to couple to a microcontroller.