EEVblog #656 - Pacemaker Monitor Teardown

[mikeselectricstuff]

In case anyone missed it - implantable defib teardown :

[babysitter]

And I am a electronics technician in medical device business, doing very little design with vanilla stuff but non-design-supporting in really interesting projects

[VK3DRB]

St. Jude medical is not a hospital it makes medical equipment so there could be tens of thousands of those devices out there.
The finger design on the pcb inside the coil housing looked like an antennae of some sort.

Antennas is plural for an electrical antenna. Antennae is plural for an insect's antenna.

[VK3DRB]

The PCB lacks of some component designators and almost no semiconductors have pin 1 markers on the PCB. A component level debug technician would probably not be impressed, especially if there were bottom side components as well. Other than that, it looks well designed.

The board would be Probably built to IEC 60601-1 Ed 2 or Ed 3.

A bit more about designing medical devices in general...

Design is very stringent. Everything is documented to the extreme, and regulatory body audits are commonplace. Often, component suppliers are requested for details that are not published in datasheets. After product release, simply changing one component or one line of code usually means the device requires full verification and validation testing. And with the software, unit testing is mandatory for class B and class C medical products, which usually DOUBLES the software development effort. Furthermore, the cost of compliance testing is severe. Medical trials are needed too. Hence development is generally very slow (taking years) and is costly. This development environment of often intense.

Typically there must be TWO means or patient protection on a medical device. In addition, earth leakage and touch currents limits are much more stringent than for consumer equipment. One example of higher standards is designing in an old RJ-45 type wired ethernet port. Your common 1.5kV isolation ethernet magnetics used in PC's don't cut it. Typically 4kV isolation medical grade ethernet ports are required. There are a few companies selling these as add-ons (also called network isolators) at very high prices to simply provide the necessary safely isolation between the medical equipment and the unknown wired ethernet network.

I know of a medical device designed with a complex array of discrete logic in 1988. The device is still sold today. The vast amount of discrete logic and A/D circuity could be replaced with one small modern  microcontroller with relatively simple software. But because of the cost of re-compliance testing, it is still the same as it was in 1988, even with its antiquated design low capacity NiMH batteries.