I am currently in an engineer school specialized in Computer Science, and I will be done with it in a little less than 2 years. I spent a lot of time on some advice websites and this stackexchange regarding PhD for the future, as I would like to do some research (based on a internship I did before), and later on join the academic world (or at least the teaching world).
The big issue I am facing is choosing a laboratory that I would like to join. The first thing that came to mind was of course Computer Science related, but the real question is : What kind of PhD can I join ?
What kind of knowledge is required before engaging in a PhD ? Could I join a bioinformatics laboratory and do a thesis on a specific protein because I have some general knowledge on how proteins work and use my computer science knowledge only as a tool, or does my thesis have to be computer science related as it is my main field ?
As for context, the main reason I am searching for another field than Computer Science is because I did not find yet a subject I am passionate about in this field. I have a lot of knowledge in a lot of different topics that I can apply at work, but none of them is something I would consider researching on.
On the other end, I am very passionate about different topics that I would love to contribute on and where computer science would be useful as a tool.