This is the topic of a short podcast by the mineralomics master (https://www.youtube.com/watch?v=Z9PljOaz1k0): how to find the specific questions of your research? And the main conclusion is that there is no recipe to find it. This is the real challenge.
But from the perspective of a biologist or a physicist studying an occurring phenomenon, the questions are usually around the why and the how. However, form the perspective of an engineer, there are also another questions which are the what and what for.
Indeed, the research needs to go beyond the understanding of the mechanisms of an event, but on how to use those mechanisms to create something useful, unique and new or better than what already exists.
From the point of view of an engineer, there are thus two different approaches to the problem. The first one is: “I want to create this, how can I make it happen?”, whereas the second one is: “We know this happens, can I make anything useful with it?”.
In the path of the research, those two questions will then intertwine in a complex way to hopefully lead to some progress.
Once the first approach is achieved, ie you managed to create what you were aiming at, then the research task gets much easier. Indeed, you can behave like the biologist or physicist studying a natural event. If you created a new extraordinary material, you will study its fabrication method. But since you design it, the understanding of the mechanisms behind is much easier. There is the possibility to change the parameters and to test experimentally everything. This understanding is a pre-requirement to show the control and tunability of your process, and is likely to broaden the potential applications. Indeed, once you know the various forces, chemistry, interactions, …, occurring during the preparation, you can define the limit but also extend it to other materials or designs. It can also be further optimized to satisfy specific needs.
The second approach is also very interesting but more tricky as there is usually a infinite possibility of systems that can be created (“[Creation] lives on constraint and dies of freedom.” André Gide). One thus needs to be aware of the current challenges. This needs a lot of expertise. Usually, at this points, brainstorming with experts in different fields helps to pinpoint an application or a system that can be of interest.
Nevertheless, if there is a difference in the object of the study, a natural event against a synthetic one, the way “to do science” is quite similar in all the research fields, as is described in the podcast (https://www.youtube.com/watch?v=JqRWBygE9VI).