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Description: A simple flex sensor 4.5" in length. As the sensor is flexed, the resistance across the sensor increases. Patented technology by Spectra Symbol - they claim these sensors were used in the original Nintendo Power Glove. I love the Nintendo Power Glove. It's so bad!

The resistance of the flex sensor changes when the metal pads are on the outside of the bend (text on inside of bend).

Connector is 0.1" spaced and bread board friendly.  Check datasheet for full specifications.

Documents:

Comments 22 comments

  • Take care how you mount these in your project.
    I was really surprised when I had two of these fail after only about 700 flexings. Looking at the failed sensors I noticed what I would call a design flaw. Most of the sensor has a thick plastic backing which helps keep it from bending too far/sharply to cause damage. However the reinforcing strip ends abruptly about 2mm before the connectors and the remaining material will easily bend far enough to destroy the sensor. (If you look closely at the back product shot you can see where the strip ends.)
    After applying strain relief to the connection area (gluing a couple of thick pieces of plastic across it) the life of the sensor has been dramatically improved.

  • This sensor is great! The reviews regarding inconsistent resistance values are fair and truthful from my experience. The ones regarding connection points failing due to being flexed may be truthful, but are not fair. If you want a sensor that is 100% ready for an industrial environment, then you will pay $150-$500 for it. It will come with pretty mounting brackets, an IP66 rating, and a housing that protects the sensitive portions. This sensor is less than $15! Buy two of them and use the first one as a learning experience on how to predict points of failure due to physical and environmental stress. Some of the negative reviews regarding the connections breaking due to flex are quite unfair…they have the same worth as saying, “My non-waterproofed temperature sensor failed when I submerged it in boiling water….what a piece of crap!” Would you also mount a toggle-switch solely by two 22 gauge wires and expect it to last for 50 years in a marine environment under daily use? Of course not! The datasheet clearly defines the ACTIVE LENGTH…and it does not include the connection points…RTFM!

  • Can anyone please give me what is the output produced for given amount of deflection? ASAP need for a project.

    • You can check our tutorial for rough values of the smaller sensor, but due to manufacturing variability each sensor will be a little different. The best practice for any project is to buy one and measure the resistance yourself at your required positions.

  • I too was having problems with the delicate end of this sensor. After applying strain relief and renforcing the pin end, I now have severe drift! It’s at ~1%/sec…really bad. Any suggestions on addressing the drift would be much appreciated!

  • i installed three of these and their resistance (laying flat) changed from 10k to 40k in just a few weeks. I’m not sure if it was due to temperature issues or i damaged the small unprotected part…
    I’m installing new ones, but I’m using the plastic part of the old ones to reinforce them :) just an idea i had and wanted to share :)

    • Can you gimmi the quantitative relation between amount of resistance vs deflection. Any formulae relating to it…Thanks in advance.

  • this items is absolutely unreliable, it’s I just waste 8 sensor after sometime using it. It’s just worth about 100 flex?

  • The schematic in the datasheet is wrong. it should say “Vout = Vin * (R2 / (R1 + R2))”. not “(R1 / (R1 + R2))”.

  • I bought one of these and I am struggling to get a decent range of values from straight to fully bent. The range difference from max value to min value is about 50 on a scale of 0 to 1023. I have tried anything from a 10k Ohm pull-down to a 390k Ohm pull-down resistor and the resistor values only change where the min and max values are within the range of 0 to 1023 while the difference between the min and max values never deviates much from 50. Is there a way to get these sensors to output a range from 0 to 1023 or is this just the nature of the device?

    • This is quite a nice toy. Some 10kOhm when not flexed, going up to some 18k when bent at 90 degrees, and some 24-25k when at 180 degrees.
      Flexing in the opposite direction shows less effect (down to some 9.4k). Apparently it can show far more than 50 different resistance values.

  • I want to like these… but they definitely are not designed that well. My biggest problem is that I need to re-calibrate them after a couple weeks of use. The resistance seems to change and it effects the way my projects work. I will try to strengthen the weak joint and maybe that will help.

  • when are these back in stock??

  • The datasheet link is broken. :(

  • These things are terrible. Absolutely terrible. I bought two a week ago to add to an e-textile project, and before I could finish, both the sensors decide that they only like to work when the “unprotected” end where the pins are is at a certain position. For sensors that are meant to be used with a lot of motion, these things are poorly designed. VERY POORLY DESIGNED.

    • See the comments here: http://www.sparkfun.com/products/10264
      It’s all about strain relief.
      I hate to say it but perhaps components that move or that are physically manipulated by the end user should have a disclaimer about needing proper strain relief.

    • Sorry to hear that. Email techsupport@sparkfun.com if you need help with them. They should be more stable than that, although the pins can be finicky.

  • Any idea where to get the connectors for these?
    Thanks.
    – Rob

    • The pins are 0.1" spaced so it’ll plug into a breadboard, or any of the female connectors or jumper wires. I’ll get them into the related items list.

  • Bravo on the “Wizard” reference. Lucas would be pleased… :)

  • Here’s some shots of an interesting use of these things for contact detection on a robot over at Hacked Gadgets:
    http://hackedgadgets.com/2008/04/13/map-bot-floor-mapping-robot/


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