Measuring the output of strain gauges

In this video I show you what are the challenges of measuring the tiny changes in the resistance of a strain gauge. The resistance of an unloaded strain gauge is around 350 Ohm (at least the one I use in this video) and a loaded one's is 1-2 Ohms smaller or larger. This is a small change, it is difficult to measure it and it is even more difficult when it is a change in the resistance of something. To make this value into a more comprehensive one, I use a Wheatstone bridge to convert the change in the resistance into a change in voltage. The obtained voltage change is still tiny (few tens of microvolts), therefore I use the built-in PGA (Programmable Gain Amplifier) of an ADS1256 AD converter to resolve this tiny change.

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[forbiddenera]

Thanks for this.. seeing you work with a breadboard made me confident in not needing the strain gauge manufacturers ridiculously expensive amplifier for testing while making our own..

[EdyBraun]

Great video! I just ordered a kit online for 4x half-bridge strain gauges that can be connected with HX711 to Arduino. My question is, your video shows only 2 wires for each strain gauge. The kit shows 3 wires coming out of each strain gauge... is that because it contains 2 strain gauges in each sensor (one in compression and one in tension configuration) to double the output voltage difference?

[loganirwin]

Hi Curious Scientist,

I have been watching your videos over strain gauges and found them to be very educational. I am looking to do my own personal project similar to your video "Measuring the output of strain gauges." I plan on subscribing to the Bachelor of Curiosity very soon, but I just wanted to ask if the code for the "4-channel data logger" can be purchased through the Bachelor of Curiosity or donations.

[boblichtenfels]

I have a basic understanding of this having done some electronics in night college. Maybe this is a dumb question as I don't know much about strain gauges. Is the voltage output linear? If put 1 ounce of weight on a strain gauge and see 1 mv will I see 2 mv if I put 2 ounces of weight on the strain gauge. I'm trying to picture how a digital scale uses a strain gauge. Thank you.

[MelJeusette]

hi, thnaks for your video. it is really nice. how did you oder your 350 ohms resistor ? i found 330 ohms but not 350 ohms ? have you a seller reference ? thanks in advance

[jasond]

Is there any limitation to the length of the leads going to the gauge? In my situation I would like to have somewhere between 6 to 9 feet. Would there be any problem with that? Thanks

[thomassantos-luis]

Hi, , the module you showed containing the bridge and opamp, found it online, is there a point on having different nominal resistance strain gauges ? if yes do you reckon i can use this module with another strain gauge ?

[integratedbio]

Did you get drift if you held a static load? I did this with an hx711 ADC and it seems to drift upwards noticeably overnight. This is very linear and im thinking of using this ADC instead.

[ciksumurni]

What a coincidence! I also use this method to measure strain on alloy specimens when conducting tension, compression and axial impact test on it. Yeah, I got very tiny changes too but I was unsatisfied with that result. Anyways, unfortunately, I have not sure if my calibration method is right or wrong? Can you show me how to do calibration?

[civilengineer]

Hello,
How can you find the stress-strain response from that data If you have the elastic modulus of that rebar? Do we need to multiply or divide the resistance of that strain gauge with the strain values, which in this case is 350 ohm?

[bobodyuknow]

You said its the via elongating causing the resistance change? I'm not so convinced. It is the thin copper traces in the polyamide that change their cross sectional area that causes the resistivity of the trace to change. An elongated via still has the same circumference.

[CuriousCat-ylby]

Thankyouuu for this :D Have you ever worked with a mems sensor system in any project? That would be a really cool video

[israelsousa]

Hello, how was done the treatment of the raw value data obtained with the strain gauges to get the strain?

[aliomar]

How about wire? please could you tell me what kind of wire you are using, if give the link like other parts will be very good?

[maybeJace]

Hi, how did you go about calibrating the strain gauge? What testing standards are you referencing?

[blue-vqxg]

hi! can you please tell me what software u re using in 11, 29, and what materials u used to connect voltage circuit please ? last question please

[ValentineDay.ForYou.]

Can you recommend a pletier?
What number plates work cool and consume the least amount of power?

[abhilashnaragund]

Dear Mr. Curious Scientist,

You are doing a great job which help students like me.
Now I would like to request/seek your guidance to know more on Wireless Transmitter and Receiver modules since I want to measure the Strain/Stress/Force acting on the moving and loaded mechanical component. So I want to mount Transmitter along with Strain gauge on the test surface of the moving element and receiver placed at a distance from the transmitter need to receive the measured data from transmitter data continuously. Could you please suggest me "tutorials/learning materials/Electronic components to be used" to get to know better? I am expecting someone who would have explained like you with my requirement.
Awaiting your positive response.
Thanks & Regards

[BrandonBaunach]

would it be possible to built a small wearable application of a strain gauge that can sense and react to small strain changes? A device about an inch wide and 6 inches long and 1/2 inch thick?

[BrandonBaunach]

Can I email you about a potential commissioned project using strain gauge? Looking to build an application that is around 1 inch wide, 6 inch long, and .5 inch tall. When bent it should vibrate (using a micro vibration motor). Should have a button that allows it to be calibrated so that it will only vibrate when deviating from the calibrated strain.