Using microwaves to kill malaria parasites and developing a way to give fetuses immunity to HIV are among the dozen ideas the Bill & Melinda Gates Foundation thinks are worth more research dollars, after giving more than 500 scientists seed money to take an initial look at some far-out concepts.

A dozen scientists or teams of researchers will each get an additional $1 million over five years to take their ideas to the next level and see if they have the potential to save lives, the foundation announced Wednesday.

The foundation initially chose more than 500 scientific ideas out of nearly 20,000 proposals for its Grand Challenges Explorations grants, worth $100,000 each, saying it would be taking a calculated risk by giving money for whatever wacky idea the world's best minds come up with to combat malaria, HIV and other world health problems.

The ideas remain highly speculative into the $1 million stage.

"They run against conventional wisdom," said Chris Wilson, director of the foundation's Global Health Discovery program. "Of course, more often than not, conventional wisdom is right."

As an example, he points to the idea of using microwaves to kill malaria parasites, from within their hosts – mice for the experiment, but humans eventually.

"That's probably not going to work," Wilson said. "But if it did work, it would be pretty stunning."

The scientist, Jose Stoute, a medical researcher who specializes in infectious diseases at Penn State University, might not appreciate that less-then-enthusiastic endorsement, but Wilson says the same thing about nearly all these grants.

"Science is a place where lots of things don't work," he said, adding that the foundation remains optimistic about these grants. "I think we're cautiously optimistic that somewhere along this path, some of these might happen," he said.

To graduate to a million dollar grant, the scientists have to prove their initial idea has merit as a potential way to save lives and that it is practical and potentially scalable and affordable, Wilson said.

Stoute said he and his co-collaborator, Carmenza Spadafora at Panama's Institute of Advanced Scientific Investigations and High Technology Services, got the idea for the project from an innovative cancer treatment involving microwaves that uses iron to tag cancer cells.

Since the malaria parasite naturally collects iron as a byproduct of its actions within the human body, they thought malaria might be another good target for microwave treatment. Stoute is working with microwave engineers to design a machine to deliver the treatment in the lab.

Collaboration among different kinds of scientists is an attribute of many of the Grand Challenges projects.

Mike McCune, professor of medicine at the University of California San Francisco, said working in multidisciplinary teams has helped a number of researchers from his university get a Gates grant.

His project, to fight HIV infection while a fetus is in the uterus, takes a number of known scientific principals and combines them in a new way.