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I'm not sure this is where it should be posted, so apologies in advance, but I'm working with an Arduino and Sparkfun's heart rate monitor AD8232 (https://www.sparkfun.com/products/12650) to gather ECG data for heartrate. I want to try to collect without "official" ECG pads, and maybe without the leg option (so basically, two on the chest, opposite sides of the heart). I have been trying with tinfoil, and I get some readings with the leg lead, but it's pretty sketchy and I have to often tailor the data I gather (I am using Matlab to process the data I get, copying and pasting from the Arduino. I know I can output to a file, but, that's another story).

So I'm curious if anyone has any non-gel and non-sticky options for pad options that work?

Scott Seidman
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Asinine
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    Try an ECG chest belt. The HR sensor is usually just clipped on for easy cleaning. – Turbo J Jun 23 '18 at 10:42
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    If you aren't careful with electrode material, you may end up [like me that time](https://electronics.stackexchange.com/a/322961/7036). – Nick Alexeev Jun 24 '18 at 03:40
  • Thanks for bringing that to my attention @NickAlexeev. I hadn't even thought of a safety factor! – Asinine Jun 26 '18 at 20:45
  • Buying electrodes should be possible from home health care suppliers. Alternately eBay and if some regulation prevents this you could use larger but unregulated (as far as I have encountered) TENS machine pads. They are generally larger and probably more expensive in sets of 4 than a bag of 50 for US$10 ECG electrodes. – KalleMP Jun 28 '18 at 18:23
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    @KalleMP I'm trying to avoid the sticky factor of those types. Edit: additionally, I have a number I purchased earlier, and they don't read very well, despite being apparently pretty good ones from 3M. I suspect the Sparkfun module just doesn't like them; the tinfoil actually worked. – Asinine Jun 29 '18 at 00:46
  • I saw some on the google search that were attached with suction cups. I read years ago of DIY electrodes that used silver salts to gain the conductivity required. The modern ones use silver as well. Regular saline works as well as far as I can recall. – KalleMP Jun 29 '18 at 08:39

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The most advisable to obtain an ECG signal is to use conventional electrodes. The alternative to the conventions is to use a textile ECG electrode, but this is experimental. You can put "ecg textile electrodes" in google and you will find many PDF files that contain research. This type of electrode is usually more expensive.

If you want to make a conventional ECG you should use general purpose electrodes, if you want to implement a wearable small size if you can try to work with a textile electrode.

I am currently working with the AD8232 and trying to use only 2 electrodes is to have an ECG signal with a lot of noise. I recommend that you use the configuration of 3 electrodes, the electrode of the right leg is there to reduce the noise of the electrical network. Techniques to reduce noise in your ECG signal: have the electrodes as short as possible, that the electrode cable is shield to GND, that the area of ​​the electrode is as large as possible. Using quality electrodes significantly improves the quality of the signal. Also, applying a pre-skin preparation helps to diminish the impedance of the skin, which allows to reduce the noise and have a signal with greater amplitude.

When working on the design of an ECG you must be very careful, and respect the electrical standards. In the case of using a self-developed electrode, you should request the certification of the electrode you are going to use. I mention this as a little advice.

Everq
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  • I'm not familiar with a "general purpose electrode", and a quick google search shows me long metal sticks. I gather the general idea (a piece of metal with high conductivity/low resistance to detect a voltage), but I am looking for something either flexible or small, as I want to attach it inside of a belt to be attached around the chest (under armpits for men, adequately positioned for women). Noise won't matter as long as I can get some sort of QRS peak or regular rhythm to analyze. – Asinine Jun 29 '18 at 00:43
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Tinfoil is difficult, because there is an insulating oxide layer that forms on the surface of aluminum. I recommend trying to grab bare (stripped) wires. For a 3-wire lead set, the ground and one other lead to one hand, and the other lead to the other hand.

Scott Seidman
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  • I was thinking that tinfoil had some sort of processing to prevent it from being naturally conductive, but I am getting readings if I have all three placed. Unfortunately, I have to use the leg spot because the other two are too noisy apparently without the additional filter. I will try your suggestion. – Asinine Jun 29 '18 at 00:44
  • Foil will function as a capacitive electrode, or at least have a substantial capacitive component – Scott Seidman Jun 29 '18 at 00:50