Building a portable ECG machine project

[lindalock]

Hello,
I want to build a portable ECG machine. I am thinking of having a display to show the wave and a SD card output to store the data, body temperature measurement.

What other things can I add to it? I want to add a simple thing. If I add enough options then I could even change the name to "portable medical tester" or something.

[CaptDon]

And what is the extent of your electronics background??? There are many schematics and DIY ECG/EKG projects to be found on the internet.

[TimFox]

Also remember that ECG safety is extremely important, since the leads connect directly to the patient's skin through conductive gels.
There are horror stories about patient electrical injury due to faulty equipment or bad connections.
https://pubmed.ncbi.nlm.nih.gov/4684516/
https://users.cs.duke.edu/~cfs/pubs/electric_hazards.pdf

[Stray Electron]

  Any kind of mis-diagnoses (on yourself or on anyone else) could also result in BIG problems.  Unless you just want to use it strictly your OWN medical evaluations, I would stay away from this.

  My 2 cents worth,

[Gyro]

My son developed one for his final year project. It worked well - front-end design is critical though, he dead bug prototyped that section before committing to PCB. As others have said, it is essential that it is battery powered (including not being capable of use or connection to the body leads if USB charging!). This is a safety red line, as well as a potential signal integrity nightmare in a home project.

As far as other functionality, think of a hospital. An ECG test tends to be a standalone activity, while standard 'Obs' combine blood pressure, temperature, and pulse oximeter. Even in theaters and HDUs, the ECG is a standalone machine.

It's important that if you are doing this, it should be undertaken as a personal interest project rather than with a view to a commercial product - approvals will kill you.

[TimFox]

Battery power is useful for safety and ground loops.
Also, be paranoid about the connectors used for the ECG electrodes so they can't be mixed up with anything else.
One horror story I remember from a local hospital (decades ago) was that the mains-powered ECG used the old-fashioned "adding machine" power connector (also used on older -hp- test equipment before the "IEC" connector became standard for mains power) that could mate with the miniature banana plugs used on the electrode cables--what could possibly go wrong?
(The pediatric patient had been moved from the ICU to radiography, and the electrode cables had been shifted from the bedside monitor to a portable monitor while the patient was away from the ICU, then re-connected after the patient's return to the ICU.)