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Description: These body electrodes were originally manufactured for use in electric therapy. While we can't condone the use of these in medical therapy, they can be useful for hobby applications. Each electrode is essentially just a conductive pad coated with adhesive gel and terminated on the opposite side with a snap connector. These electrodes are sold in pairs along with an electrode lead with a snap connector for each at one end and a 2.5mm jack at the other.

Although we have no information available regarding the voltage and current tolerance of these electrodes, it's probably safe to say that they will handle much more power than you would ever want to conduct through soft tissue!

The adhesive is a gel similar to what you might find on Pasties or those sticky hand toys you (try to) win at arcades and carnivals. After a few applications, the gel collects contaminants and becomes less adhesive, rinsing them with water will help it regain its adhesive properties.

Note: This product is NOT a medical device and is not intended to be used as such or as an accessory to such.

Features:

  • 5ft cable
  • 2.5mm connector
  • 2x3" Electrode
  • Self-Adhesive
  • Snap connectors

Comments 78 comments

  • I don’t think this product is at all dangerous. After all it is just a few pieces of metal and some gel. You could burn yourself with the soldering iron, cut yourself with the hobby knife and so on for many products.
    The issue at hand is that its uses could be potentially hazardous. SparkFunions, DO YOUR HOMEWORK! There are resources regarding safety for managing anything electrical attached to the human body. Take it from me, I am an Electrical/Biomedical Engineer (for real).
    If you take only one thing away from this: using batteries reduces the risk of AC line voltage shock, always avoid sending AC across your chest, even arm-to-arm & leg-to-arm. Stimulating muscles in your arms and legs is less risky, but know the risks.
    Otherwise, I look forward to ordering me a handful of these. Any chance of getting more specs?

    • I’m sorry to belabor the point here, but as someone who has taken courses, (yes plural), on electrical safety, biological effects of electricity, and bio-measurement, I feel the need to clear up certain common misconceptions in this area.
      Electricity can have negative effects on human tissue and must be handled with care and understanding. But it has also been used for decades in a variety of ways.
      Enough direct current can heat and damage cells.
      50-60Hz AC (what comes out of your wall) is the frequency to induce full tetanus, which meas the muscle contracts and cannot relax. Which is why if you grab a 60Hz line, you can’t let go. Also, bad for the heart, since it holds in a contracted state.
      At much higher frequencies, the skin effect plays a role, meaning more current flows on the surface. Also, if the frequency is high enough, the cells don’t have time to contract…

    • Then what the heck am I going to do with this 12V - 95V shock board I just made?

  • I say remove all safety labels from these, and all of these safety comments, and let nature take its course. It’ll be better in the long run for the gene pool.

    • It would be good publicity if Sparkfun was mentioned in a Darwin Award write-up….right?!

    • Sparkfun: Chlorinating the gene pool!

    • Safety with this sort of device isn’t necessarily common sense. An uninformed individual might plug this into a 120VAC to 5VDC adapter and not live to realize his mistake.

  • can you use it to re-animate dead things :D ?

  • Sparkfun says these are harmless on their own, but the only item listed under related products? Sparkfun band aids :)
    But seriously, saying that these items need a warning label is like saying kitchen knives, bicycles, or bathtubs should come with warning labels. Unless you intentionally misuse it, it’s perfectly safe.

    • Seriously, there are bicycles with warning labels.

      • Talking about warning lables…
        I am surprised that no one makes them put a warning on 9 Volt batteries; that your not to put your tongue across the contacts or it could cause you bodily harm while driving ;-)

  • Good for ECG/EEG/EMG (Well, maybe not EEG).
    Bad for defibrillators.
    Also, you might want to put a note that this can kill you/put you in Vfib if used improperly. (i think this is one of the most dangerous product sparkfun has. Not that it’s a bad thing)
    “If the current has a direct pathway to the heart (e.g., via a cardiac catheter or other kind of electrode), a much lower current of less than 1 mA (AC or DC) can cause fibrillation. If not immediately treated by defibrillation, fibrillations are usually lethal because all the heart muscle cells move independently instead of in the coordinated pulses needed to pump blood to maintain circulation.”

    • Since I don’t think people will be applying these directly to heart muscle tissue (but who knows), I think this quote is a little more relevant:
      “A domestic power supply voltage (110 or 230 V), 50 or 60 Hz AC current through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60 mA. With DC, 300 to 500 mA is required."
      Clifford D. Ferris, Electric Shock, chapter 22.1 in Jerry C. Whitaker (ed.) The Electronics Handbook, CRC Press, 2005, ISBN 0849318890, pp. 2317-2324
      An important thing to know is that for DC, the current needs to be high enough to damage cells. For 60Hz AC, (the worst frequency for V.fib. risk btw) the current needed is less because you only need to disrupt the natural synchronization of the heart.

      • Since I don’t think people will be applying these directly to heart muscle tissue (but who knows), I think this quote is a little more relevant:
        These electrodes lower the skins resistance to almost nothing. Ventricular fibrillation (a cardiac rhythm in cardiac arrest) can be induced with very little current (1mA DC) if you create a circuit that goes through the heart, and your electronics leak current or output current through the electrodes.

        • I don’t mean to pretend as if I know anything about this… but it seems to me that the idea of a surface electrode lowering skin resistance is akin to the idea that laying an insulated wire against a metal plate would lower the insulator’s resistance… The only resistance effected with the use of electrodes is that between the device and the skin’s surface. The only way I know of to lower skin resistance is to induce certain physiological changes or to jump to percutaneous electrodes.
          EDIT: Please don’t play with percutaneous electrodes. lol

          • If you break the skin in both sites (i.e. percutaneous electrodes), the resistance is quite low (think of the resistance of non-deionized water). If you really want to know the resistance, just put two of these pads on your thigh, a few cm (or inches) away each other and measure Ohms with a DMM. I will tell you now, if you get less than 500 Ohms, there’s probably something wrong with your multimeter.

        • Actually you need to read what you quoted more carefully, it DOES matter where you place it, the extremely low current you quoted is only valid if the electrode provides a “direct pathway to the heart”. In other words these electrodes will only be dangerous at the current level you mention if they either contact a surgically implanted heart catheter or if they come into direct contact with the heart muscle, it is not at all reasonable to have the warning you propose.
          The warning BlackJester suggests is sensible, but really you could get the same effect by jamming a wire into your skin, these pads just make it more comfortable.

        • To begin, you can’t induce fibrillation with 1mA DC unless you place electrodes directly on the heart tissue. I think you are misreading the Wiki quote you included.
          “The current may, if it is high enough, cause tissue damage or fibrillation which leads to cardiac arrest. 60 mA of AC (rms, 60 Hz) or 300–500 mA of DC can cause fibrillation."
          Second, even wet, skin resistance is still on the order of 1kOhm.
          "The voltage necessary for electrocution depends on the current through the body and the duration of the current. Ohm’s law states that the current drawn depends on the resistance of the body. The resistance of human skin varies from person to person and fluctuates between different times of day. The NIOSH states "Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body’s resistance to 1,000 Ohms,” adding that “high-voltage electrical energy…"
          -Wiki

          • Please, everyone be informed! Read the entire article before you make decisions. If you take proper precautions, read the relevant background info, and avoid grounding and AC scenarios, you can work safely. Be smart!
            If a hobbyist injures themselves because they were playing with something they didn’t fully understand, I’m sorry, but it’s not SparkFun’s fault.

          • No, you can induce fibrillation with 10uA. “current as low as 10uA (microampere) directly through the heart, may send a patient directly into ventricular fibrillation."
            Then if you use electrodes, the skin resistance is even lower.

            • When they are talking about “directly through the heart” they are referring to microshock.
              “intracardiac electrical conductors, such as external pacemaker electrodes, saline filled catheters"
              If you are going to quote, at least quote the entire reference please. Selective quoting can lead to further confusion of the facts.

    • These are conductive adhesive pads. They will do nothing to you directly. We do not and will not sell electronics for them.

      • “We do not and will not sell electronics for them."
        Umm… Thats even worse. People will try to build their own front end for these and might not know how to properly isolate the electronics from the body.
        I realize that the electrodes are harmless directly, but when paired with faulty electronics without isolation, thats when they become very dangerous.
        I really hate how SparkFun is ignoring this. I don’t want to hear a hobbyist dead because of:
        * Not knowing the risks associated with electrodes and electricity.
        * A non-isolated analog front end.
        I think you should continue carrying these (I’ve been waiting for these :D) but at least have a warning somewhere.
        I don’t understand why someone can’t put a note somewhere saying that these electrodes can cause death if misused.
        I know you claim that the electrodes are not a medical product (however it really is) and should not be used as such, But that doesn’t stop people from using it for it for it’s real intended use.

  • for safety can you not just put a diode to only allow current to flow in one direction?

  • Sparkfun should offer a 2.5mm jack

  • I just bought these today and hope to find these useful I am currently testing with biomedical engineering and have came up with this great idea so ill see what my out come is also I bought two pairs

  • Maybe I am an idiot, but I can’t find any female jacks for this on Sparkfun, only 3.5mm….

  • So umm. How do you use them! :P

  • Purchase this product and in my country say they need a health standard for impotacion of this product, I think is missing more information about this product because I was not allowed to import and do not know if my product leaving the customs or back to sparkfun, if there any reimbursement for such cases

  • Has anyone used these in a project of any kind yet?

    • I’m using a pair I already had as an Electromyogram (EMG) detector for muscle activity. I feed it into a differential amplifier, then to a highpass filter, then to a rectifier, then to an low pass amplifier, and lastly to a dsPIC micro. They are pretty sweet. I’m able to detect flexing of muscles and also heart beat. You’ll need to buy 2 pairs though. You’ll need one pair between the area to be sensed, and another sensor to put on an area of your body that will connect to ground. I may post more details when my project is finished. Here is a great reference that will definitely get you started: www.ece.utah.edu/~harrison/ece3110/Lab5.pdf

  • Hey guys, I’d appreciate any input you offer.
    I have 2 pairs of similar electrodes from a TENs unit laying around the house. I’m thinking of employing these in my senior design project. Could someone tell me if these would be effective to monitor heart pulse?
    Here’s how I would go about it, but please correct me or offer suggestions:
    I would imagine setting up one electrode right before the hand (on the wrist) and the other electrode about 4-5 inches down, both sensors on the underside of the forearm. Then I would run the output of the V+ electrode through some kind of amplifier and into a PIC A/D converter. I have a dsPIC dev kit. I don’t know if I’d need digital signal processing or could code in an easier manner. Can anyone provide some coding or code references for detecting a peak in the signal? Would this method of setting up the electrodes work? Thanks.

  • Speaking of electrocautery, when can we get a kit for that? Possibly the coolest medical device lay people don’t know about.

  • The manufacture of “Warning Labels” MUST be the fastest growth industry in America? Just a thought…
    FOR SAKE, this product is just an insulated piece of wire, with exposed metal on both ends.
    Let’s face it, the idiots that a number of you are worried about, will NOT spend $7 on contacts and a socket for their ‘DIY taser’ they are building from an old electric fence box they found on uncle Bill’s farm!!!
    We all know our idiot will simply tackle Billy-Bob to the ground and connect the new ‘toy’ to his nipples with the battery jumper cables from the tractor. After all, the whole purpose is to see if he can get Billy-Bob to twitch hard enough to do a full 360 degree somersault. Them flimsy little leads are no where near as appealing as hefty 60 Amp jumper cables.
    -forgive me for saying ‘Nipples’, I was being polite. We know the ‘probes’ will probably be clamped further south of the border.-.
    ..
    P.S. Idiots wont spend money on a quality product, they will make their own from tin-foil and jumper cables etc - These decent contact pads will be purchased by people who want to do things properly - and carefully!

    P.S.S. Idiots don’t read warning labels either!

    Now, for those who are looking forward to using these probes for real projects:
    | Post by Austipodean | July 10, 2011
    | with a link to SiliconChip Magazine's
    | nerve stimulation circuit.
    If you didn’t get a kick from that link, this one’s a guaranteed screamer.

    Don’t forget, before testing a new project yourself, always paint your name across your chest, so the ‘Darwin Awards’ people don’t spell it wrong!

    Anyhow, must run, I just getting the kinks and final wrinkles out of my “Electronic Viagra” project - watch out for it in SparkFun’s ‘Featured New Product’ list in 3 or 4 weeks.
    Cheers,
    Paul

  • There are so many good uses for this. But i agree, you could hurt yourself in short order.
    Remember to always use multiple redundant safety resistors and don’t use anything connected to AC mains unless you know what your doing. really. just don’t. if you must,be sure the output is isolated!!!
    anything across the chest or head is a dangerous(unless its a sensor not a shocker)
    but otherwise, great product!

  • Can you say “DIY Elektro Kardiogramm”?

  • You could zip-tie a bunch of these to some wheels and make a car that can drive up walls and on the ceiling :D

  • Can those be used to detect voltage ?

  • Add this product to the list of things that can hurt you if used improperly (already on the list are the Geiger counter [high voltage shock hazard], reflow toaster controller [burn down your house], and super-bright leds [ruin your vision]).
    Seriously, these things should not be fooled with unless you know what you are doing.
    On the electro-stimulation side, there are control boxes available to use with this sort of product. These are usually used for muscle stimulation and pain control applications. A properly designed stimulator is electrically isolated for safety and provides an AC signal that minimizes cellular damage. The general rule for any sort of electro-stimulation is to never use it anywhere above the waistline or lower back, otherwise it can kill you.
    On the sensing side, interfaces designed to read electrical signals from the body must be designed so that they are isolated and so that they cannot inadvertently inject current into the body.
    The description note saying “This product is NOT a medical device and is not intended to be used as such or as an accessory to such.” is probably not sufficient to protect Sparkfun from potential liability; this product should be marked as “NOT FOR HUMAN USE”.

    • Hey, that gives me an idea: I should buy some, stick them to my legs, and attach an LED, then go for a run. Then I should stick them on my crazily strong sister’s stomach and see what happens when she does 150 sit-ups.

    • I would guess that if creatively used, one could injure oneself with almost every product we carry. We aren’t going to start putting choking hazards on small ICs…
      Thanks for looking out for us, but we’re fine. This is a harmless product that of course could be used to cause harm if mis-used.

  • These are used on electronic muscle therapy devices for people with problems such as a severely pulled muscles, or stressed muscles under tension. my mom had to use something like this hooked up to a small machine to help her pulled neck muscles after a car accident.

  • Hmm… I agree with MTG.
    Normally skin resistance is a couple of hundred K which limits current through the heart pretty well until you get to higher voltages. Electrodes like these can reduce the resistance through the skin to a value low enough that voltages which are normally relatively safe can become dangerous. 9v and under battery powered (vs line powered) circuits are probably fine. With line powered circuitry leakage currents (or miswiring) could cause real problems.
    BTW, Pasties?

    • It lowers resistance very much. Remember it only takes 10mA to stop your heart/put you in cardiac arrest. Voltage doesn’t matter.
      BT: Conductive gel.

      • I = E/R. I was trying to make the point that as R (skin resistance) falls, for a given E the danger (I) will increase. I guess I should have mentioned ‘I’ explicitly instead of leaving it as an exercise for the reader..:-)
        Conductive gel on Pasties..? Who’d a guessed? Maybe that’s how they make them light up in the dark! (Just kidding)

        • WTC are P(edit: *****)? Some kinda crazy, messed up novelty twinky-like Pastry?

          • Close. Pasties were/are a now quaint costume requirement for strippers operating in locales that would not allow exposing female nipples during performances… Sometimes equipped with sequins or tassels. And evidently attached with conductive gel.

  • tDCS, anyone?


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