I don't think there is any real danger in connecting an "electrical" sub-d to a "fluid" sub-d. You'd just have a non-working connection from both sides.
It's similar to many devices having RJ-45 serial console ports, that look like network ports, and if you accidentally connect the wrong cable to it, nothing bad happens.
On the other hand, I could really see hybrid connectors as a solution, i.e. have 4 electrical pins and 5 fluid pins. That way you could have some signalling between the devices and not start pushing fluid through the tubes unless a "correct" device is attached.
> One of the key barriers to the widespread adoption of microfluidic technology outside of specialized research laboratories (e.g. in clinical settings) is that microfluidic devices are often complex to operate.
If their goal is to make something for clinical applications, having an unexpectedly non-working connection could be a problem. Non-"standard" RJ45 and DB9 connections are notorious for confusing end users.
It's similar to many devices having RJ-45 serial console ports, that look like network ports, and if you accidentally connect the wrong cable to it, nothing bad happens.
On the other hand, I could really see hybrid connectors as a solution, i.e. have 4 electrical pins and 5 fluid pins. That way you could have some signalling between the devices and not start pushing fluid through the tubes unless a "correct" device is attached.