[ECG]

[qwerty]

hi , is it possible to obtain the ecg, heart rate using  both thumb or index fingers on 2 metal electrod? if so , is there any explanation and circuit design i could use ?
thanks.

[FriskyFerret]

Your English is not precise. Do you mean an ECG with one electrode on each thumb?

If the answer to this question is 'yes', then of course it is possible. Picking up the signal from the wrists is a better method. The contact pressure must be absolutely constant and the muscles in the hand, arm and shoulders must be fully relaxed to quiet the signal down and reduce artifacts. Even then the signal must be low-pass filtered.

[qwerty]

ah , sorry for bad english.
yeah , one electrod on each thumb. is there any circuit design / schematics that i could use ? thanks

[rtm]

How about to use light through finger? There is a circuit:
http://www.picotech.com/experiments/calculating_heart_rate/

[persiangulf]

You won't be able to get an ECG recording from the thumbs...... ECG's primary purpose is to create graphs showing the rhythmical electrical activity of the heart. By the time the pulse reaches the thumb, there would be a delay, and many of the vibratory pickups essential to get an ECG would be lost/faint in the thumb area due to the distance from the heart.

You CAN get a pulse/heart rate from the thumb, but not an ECG. To get an ECG you need 7 precordial cords around the chest area an some pretty complex circuitry.

I heard of an company claiming in the BMJ to have been able to pick up the hearts electrical activity remotely, but never had a product to show this claim.

So ECG = you need to place the precordial leads near the heart. No possibility of reading an ECG from the thumb.
Pulse rate = you can read the pulse/heart rate from almost anywhere in the body where there is a pulse. Neck, thumbs, wrist etc. Some areas are easy to pick up the pulse from, some areas are harder.

If you need a precise reading of the pulse, avoid the thumb area, try to use the wrist. But if you're after an average reading of the pulse you can use the thumb. With most types of designs you would need to use both hands/thumbs.

You can use any type of metal on the thumbs or even a circuit board with a large copper area as a sensor. You can use a 555/Op amp to read the pulse. It's pretty simple. Here is an example project: http://www.cpureadyconsulting.com/heart-rate-monitor-pulse-reader.php

Hope I have helped you. If you any questions, please ask.

[FriskyFerret]

You won't be able to get an ECG recording from the thumbs...... ECG's primary purpose is to create graphs showing the rhythmical electrical activity of the heart. By the time the pulse reaches the thumb, there would be a delay, and many of the vibratory pickups essential to get an ECG would be lost/faint in the thumb area due to the distance from the heart.

persiangulf, you have absolutely no idea what you're talking about. Why do you even speak if you are know nothing about the subject? I regularly use a portable two-lead ECG monitor on my wrists. It was designed to be used on the wrists and it also works on my thumbs.

You should be banned for purposefully spreading disinformation on this board.

Here's my wrist ECG monitor. It interfaces to a PC or a telephone line via acoustic coupling. There are different brands but Pace was the original. Google 'transtelephonic ekg' for more info on these units. They typically use a flexible stainless watchband as the wrist straps. They used to be available on eBay for $10-$20 US. I bought three different brands off eBay, compared them, kept the best one and threw the other two away.

[persiangulf]

My brother is a doctor, and I do know about transtelephonic ecg, i've seen many of them. I just spoke to my brother, the only places to use for ECG are the chest, wrists, above the ankles and near the shoulders. So no, YOUR WRONG, you can't use the thumb, as I mentioned earlier because the vibratory pickups are faint in that area, the only thing it could perhaps be used for would be some abnormal heart rhythms picked up using the pulse as source, but the thumb would exhibit no data that demonstrates the heart electrical activities which is what ECG is proposed for. Just because they call it transtelephonic ecg does not mean it picks up the hearts electrical activity. So you have no idea what your talking about. In addition, if you digged deeper in google, you would find out the most effective way for an accurate ECG is precordial leads across the chest, and this method is always primary opposed to any other pickup areas. And to be banned for saying what I know? Your a very extreme person... God help you.

Sometimes transtelephonic ECG's use wristbands in conjunction with a thumb clamp with thumb clamp only being used for pulse pickup and nothing else.Go on, paste us the manual or some evidence to say the machine you have can be used on the thumbs?? An ECG is based on the hearts electrical activity inconjunction with the pulse. Most home ECGs use the pulse to detect abnormal hearth rhythms, some do use the hearts electrical activity, but they won't pick up anywhere near the thumb...... the name ECG is misused, when infact devices such as http://www.aerotel.com/en/products-solutions/heartline-ecg-monitoring/heartone.html only report abnormal heart behaviour using the pulse as source. If you read carefully, it even mentions "Pediatric use (with chest electrodes)" and also features a chest electrode. Even then, it won't be a full ECG device, as it will only pick up limited amounts of electrical heart activity, just about enough to report if there is something wrong with the heart rhythm. I hope you can go away now understanding what ECG is.

Posted on: February 04, 2008, 12:43:05 00:43 - Automerged
and qwerty, don't waste your time trying to read an ECG from the thumb, even if you do pick up something, the results would be inaccurate dependent from person to person. You could perhaps use the pulse it self to draw an ECG graph, but alot of important data would be missing. If you are trying invent a machine for a thorough ECG using the thumb good luck.

[simma]

Dear persiangulf,

You are correct in your enthusiasm to help others and wrong in your understanding of ECG . Please get your fundamentals correct. You are correct in saying "An ECG is based on the hearts electrical activity " but wrong in saying "but the thumb would exhibit no data that demonstrates the heart electrical activities which is what ECG is proposed for". Our body can conduct electricity and hence, ECG signals can be picked up from the thumb. However, as contact area at the thumb is little, they are not preferred.

A pulse (or pulse rate) is a measure of the heart's pumping action (contraction of the heart) expressed as BPM (Beats Per Minute). It conveys only a little information of the condition of the heart whereas the PQRST complex in ECG waveform tells you the inside story of the heart. A two leads ECG gives you a quick snapshot of the heart condition and used for monitoring purposes alone. However for diagnostic purposes a 12 lead ECG is used, which is acquired from the chest area.

Pulse rate can be obtained

1. by detecting the QRS complex in the ECG waveform

or

2. by Photoplethysmography which is based on the principle of optically detecting the change in the blood concentrations due to heart's pumping action. Pulse Oximeter works on this principle.

or

3. by Tonometry (based on mechanically detecting the blood flow), very uncommon in usage now.

Let me stop here. Please, read a good Biomedical engineering book for a better understanding.

[persiangulf]

ofcourse I know the hearts electrical activity brushes off all over the body.... I have experimented with an oscilloscope in my time. Even a child knows the body conducts electricity. When I said the thumb won't exhibit no data for the hearts electrical activities I did not mean suddenly you move 1 inch up to the wrist there is data, and suddenly there is no data at the thumb. Now you can look at what I said digitally or like a human. The last 2 methods you mentioned are only for the detection of the pulse. You try to detect reliable "QRS complex" from the thumb to create worthy ECG data and I can assure you you will have a million dollar circuitry in your hands. If you also studied the human body more, the hearts electrical stamp varies from area to area.. infact all types of electrical waveforms from the body have hotspots. Now if you want, you can also try to measure ECG data from the anus or the tip of your nose... maybe you could make an ear ring transtelephonic ecg device and become rich..... but in practice, its not as simple as simply using 2 leads to get reliable ECG data. Maybe you could suggest a design to also pick up the brains electrical acitivity from the toes... that would be interesting. Even the transtelephonic ecg machines are known for their unreliability, interference, etc. which is why doctors always also conduct ECG recordings in the hospital. Like I said before, the best areas for ECG pick up, the ankles, mid shoulders, wrists, and chest. Since you're are purist, you can even argue ecg data can be picked up harmonizing radio waves with the bodies waveforms using a remote sensor far from the body.

[nacho1]

qwerty. of course you can do that.
First you need an instrumentation amlifier,  you can made one with 3 comon op Amps. or build una integrated like the ad620.
after these stage you should pick up a noisy ecg signal.
the second stage is a lowpass filter with a cutoff frecuency arround 40hz. the QRS complex or the BEEP  has a low frecuency less than 30 hz.
and a high pass filter wiht a cutoff frecuency  of 10hz to eliminate the p and t waves. I dont remember the exact frecuencies, but you can try with  R-C filters
after these satges if the signal is noisy you should put a notch filter to eliminate the electrical noise from the power  lines.

remember since you are using  2 wires you dont inject the common noise back to the patient so skipping these technique you need to refine the filtering after the instrumentation amplifier.

besides the only reliable data that you can obtain its the QRS complex in form of a bipolar peak. after that you should do the math to obtain the heart rate

[simma]

persiangulf,

Looks like English is not your native language and you are using a translation engine which looses the essence of your message.



 

[lillbear]

heh well i dont know nothing about anythin, but i usually check this link first 

so...http://en.wikipedia.org/wiki/ECG

yours

[FriskyFerret]

My ECG unit works just as well on my thumbs as my wrists. I tried it.


Enough with the "my brother is a doctor" guy, and back to qwerty's question, Everyday Practical Electronics had an DIY ECG article in the November 2007 issue. Anyone have a link?

Looks like the pickup electrodes are mounted on the chick's wrists. Hmmm, aren't the thumbs just a few inches from there?

[simma]

qwerty,

If your intention is to measure just pulse rate, you can go for optical sensing. I have done ECG and optical method and both works fine. Which one is good ? -> depends on your application. If it is for commercial application, I would advise you to improve your knowledge on this subject before you embark on the project. Otherwise, for an amateur project you can use any one of the many projects available on the net. But their merit may vary.

I am attaching an article from elektor for your reference.

[hoda]

here is a simple design for ECG amplifier
http://ebasic.easily.co.uk/01A059/00B038/anddes.html

[tuvoj]

Have done both ECG and EEG and I can tell you that optical will get you pulse only---(also Oxygen levels if you are into reflectrometry)

BUT, to get TRUE ECG, you will have to go with silver/gold electrodes and cream, and play around with position on the chest/back---NOT arms or hands!

Take a look at a few med supply catalogs for electrode sourcing...

Cheers-Tuvo