[symaxian]

Are the techniques described in the article still in use today or have they been superseded?

[kens]

My understanding is that modern techniques are similar, but the tradeoffs have changed as chip voltages become lower and transistors become smaller. (Admittedly, I don't know a lot about modern techniques.)

This article, from a company that designs ESD circuits, describes various modern techniques: https://monthly-pulse.com/2022/03/29/introduction-esd-protec...

[lpribis]

Yes, using 2 or three flip flops in series to prevent metastability is still common practice today. As is using diodes in that configuration for esd protection.