Disclaimer: while lab rotations are an integral part of the CBB degree and some important aspects are defined in the study regulations, how your specific lab rotation(s) will look like depends very much on the research group (and by extension department, company or other institution) you do it with. Accordingly, please treat the advice below as such (and not as rules set in stone and delivered by an ancient computational biology prophet).
Your internship/lab rotation academic supervisor cannot be the same as your thesis supervisor, even if the internship is in industry and thus contact with your academic supervisor might be limited. You also have to do your thesis in a different group/company as at least one of your rotations/internships. For further info refer to the Studienreglement (only in German): https://rechtssammlung.sp.ethz.ch/Dokumente/324.1.0600.20.pdf.
Where to do lab rotations?
Anywhere you want (almost). The more common options are
- research groups at ETH from relevant departments such as D-BSSE (obviously), D-BIOL and D-INFK but D-USYS or the Seminar for Statistics (part of D-MATH) can provide interesting opportunities.;
- research groups at UZH, some of which you might get in touch with through courses offered by UZH;
- and pharma or (bio)tech companies
but of course you are not limited to these. Other research institutions such as universities or research insititutes elsewhere in Switzerland, Europe or the world can be an option too. Venturing further should be covered by the study regulations in most cases but might take a little more effort to get officially approved, so before applying for less traditional options make sure you have a reasonable plan for how to go about this and potentially check with the study administration or coordinator of the CBB degree before commiting to anything with an external company or research institute. The most critical part is to find someone at ETH (or an institution associated with the CBB degree) to grade your report. This cannot be done by an external person. A natural choice would be to ask your Mentor if she/he would accept this task. You should not have any issues finding lab placements within the department, if you do please contact the department directly.
How to apply?
How to go about applications is almost as varied as the places you can go to for your lab rotation. Some research groups advertise projects on their website or through one of the mailing lists at ETH. In many cases, however, a lab rotation happens because you, as a student, show some initiative. This could be by talking to a professor or postdoc after a lecture (... once these take place in person again) or by sending an email. If you choose this route, it is most likely advantageous if you know (roughly) what their group is currently working on and maybe have even read two or three of their (recent) publications to have a good idea of what they are spending a large part of their time on.
If you decide to go for a lab rotation in industry, positions are more likely to be advertised (e.g. IBM research in Zurich will more or less frequently put project proposals on their website) but even here it could pay off to show some initiative and try to create your (temporary) position by talking to CBB alumni or older students who currently are or have previously been at the company you are interested in.
When to do lab rotations?
As soon as you are done with your additional requirements, you can do your lab rotations at any time. If you have additional requirements, you might not be able to register your lab rotation officially via mystudies until you have passed the relevant courses and the study administration might be reluctant to help you "overwrite" this constraint.
"How to do" lab rotations?
Part-time lab rotations are possible with most research groups but most likely you have to be proactive about this by asking.
Working remotely for lab rotations, e.g. if you live in Zurich but do your rotation with a D-BSSE group based in Basel, is often possible (and was even before COVID-19) but this of course depends to a large part on the type of work (computational vs. experimental) you do. Hybrid models where you go to the office of the research group for one or two days a week are also often possible. Note, however, that even though commuting might feel unusual after these long months in home office (or study), in-person interaction within a research group could be an important part of your lab rotation experience depending on the atmosphere in the research group you join and your style of working.