Investigate some of the challenges faced by your clinician. What would they most like to change? How could they better serve their patients? Personal interviews (with your clinician and others in the field), consultations with professors, and google searches are a good way to get started.
Begin to thoroughly understand the problem, so that you can begin to create the solution. Books are great for this step. And articles. Remember this simple strategy: Use books to provide background, then use journal articles to back up and support your findings, and provide the most up-to-date information. (See Books/eBooks and Find Articles.)
Read journal articles and research reports that describe the current understanding and treatment of the condition. See the databases linked on Find Articles to find these. Patents can also be an excellent source of this information, as they sometimes give a review of a device in context of the medical need. A good summary of this step is to use information found in articles, research studies, and patents to address specific questions raised in your initial assessment of the medical need.
Patents are again a great source of information, this time to describe the workings of devices that are currently on the market (granted patents) and in the pipeline (published patent applications). And again, articles are a great source of information - this time focusing on the device itself rather than the medical need. Knowledge of industry standards and government regulations - particularly FDA - is needed to determine how your device might be regulated. See Medical Device Regulation for a detailed description of this step.
Once the design phase is completed, it is necessary to understand the market for your device. How many people have the condition you are treating? How many procedures are done every year? How will your device impact the market? The library has invested in several key databases that address these questions. Articles in business databases can also be a good source of information. (see Market Research resources.)