Medline is a great place to start. It has a huge selection of articles on medical topics from a large variety of medical journals.
Web of Science Core Collection is another great scientific database, with articles from top tier research journals in all fields of study. It also has some specialized features.
Engineering Village is a VERY comprehensive database covering engineering aspects of your topic. It covers all of the engineering disciplines, and a huge selection of journals and conference proceedings.
You may also want to look for books on your topic. Books are great for background information. If there is a book published on your topic, you want to know about it.