I place all of my research work in the public domain. I believe university research should serve society at large, and should be freely available for anyone to use and learn from. I have nothing against patents in principle: Industry invests huge amounts of time and money in R&D and needs to protect new ideas to give them the confidence to continue to invest. As academic researchers, I favor staying ahead by running faster, rather than protecting our backs. It keeps us on our toes and makes us more innovative. And it makes it much easier to work with our colleagues in industry.
I am very lucky that my employer gives me the discretion - as a Principal Investigator - to decide which of my ideas are placed in the public domain. Since 1999, I have placed all my research in the public domain.