DIY Heart ECG wearable recorder (Holter monitor) - Page 1
Forum section: electronics / projects

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 16, 2013, 02:55:14 pm
content: Experiencing strange sensations and feelings in my chest I did the only logical thing... Make a ECG recorder!I bought a front end fromhttp://www.100randomtasks.com/ecg-front-endand connected it to an Arduino Nano. (Don't worry, no Arduino IDE's where harmed in this project...)The data is stored in a 16MB flash chip.The PC part where written in C#, my first program in that newfangled thing called OOP.See pictures and ZIP file for source code. If there is interest I can provide more details.I was able to catch a few of those glitches, see picture. (Third line in the middle)Now tell me... How much time do I have?

author: mmagin
author_rank: Frequent Contributor
timestamp: September 16, 2013, 03:04:24 pm
content: While this kind of configuration seems to work fine for the simple heart-rate monitors used when people are working out, I seem to recall that most ECG setups (even simple ones) use some kind of driven guard electrode attached elsewhere on the torso.

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 17, 2013, 10:31:14 am
content: Quote from: mmagin on September 16, 2013, 03:04:24 pmThe ECG front end has resistors from each lead to Vref to keep the common input voltage in range for the input amplifier.

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 17, 2013, 10:33:25 am
content: Quote from: Pippy on September 17, 2013, 10:14:09 amHey, that is not to bad, I get to see another summer!

author: saturation
author_rank: Super Contributor
timestamp: September 18, 2013, 07:26:51 pm
content: That strange 'blip' above the red line is a premature ventricular contraction.http://en.wikipedia.org/wiki/Premature_ventricular_contraction

author: mmagin
author_rank: Frequent Contributor
timestamp: September 18, 2013, 09:26:27 pm
content: Quote from: Kaptein QK on September 17, 2013, 10:31:14 amThat might be enough, I'm not experienced enough to be sure -- I was thinking the movement of the leads and amplifier relative to the patient could cause enough interference in the signal to be a problem, maybe. I've only done this once long ago in a college class with an instrumentation amplifier and a commercial A/D board. I think we had a third electrode on the torso which was driven by the amplifier output or something. Possibly this was more essential when the amplifier wasn't mounted right on the subject

author: Chryseus
author_rank: Regular Contributor
timestamp: September 19, 2013, 12:17:06 am
content: I see nothing wrong besides a PAC followed by a PVC on the second line which is nothing to be concerned about, first and third line is due to noise from movement or the leads making poor connection.

author: Psi
author_rank: Super Contributor
timestamp: September 19, 2013, 02:13:23 am
content: You should put a bright LED matrix on the box, so at night you actually see your realtime ECG waveform through your tshirthehe, electrolumenesent array t-shirt that shows realtime ECGNow that's a good idea for a kickstarter.Actually i think a flex PCB with bright SMT leds would be better. Best to make it not part of the tshirt at all.Just have a internal pocket behind the chest where the flex board sits.

author: Psi
author_rank: Super Contributor
timestamp: September 19, 2013, 02:24:05 am
content: Id like to see your doctors face when you show up with your own home built ECG readout of the issue.

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 20, 2013, 01:22:06 pm
content: Quote from: saturation on September 18, 2013, 07:26:51 pmThanks!

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 20, 2013, 01:30:08 pm
content: Quote from: Chryseus on September 19, 2013, 12:17:06 amThanks! The noise is due to movement.The incident which made me make this device was much longer (minutes), but I did not have other symptoms. It only happened a few times during a hour.So I guess I will see several summers come and go!

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 20, 2013, 01:35:18 pm
content: Quote from: Psi on September 19, 2013, 02:13:23 amHaha, good idea! Imagine a date: "Your BPM is rising. Are you getting horny?"

author: Kaptein QK
author_rank: Regular Contributor
timestamp: September 20, 2013, 01:39:52 pm
content: Quote from: Psi on September 19, 2013, 02:24:05 amUnfortunately I do not have recording of the issue which made me make this device. Since there where no other symptoms I will let the doctor wait.

author: Psi
author_rank: Super Contributor
timestamp: September 23, 2013, 09:23:57 am
content: You have the screen capture of it.