I’m looking for a young adult book I read around the mid 2000s. I was living in Bahrain at the time, but the book was in English and I think it was bought in England (Manchester). I think the book had a purple color and ~250 pages. It was about some teenagers winning some sort of science competition to work at this world famous lab where they all had their own projects and had whatever materials they needed provided by the company.
The main story is about a pair (boy and girl, I think around early teens) that built tiny robot with true AI. The story starts going downhill when other teenagers go missing when they don’t show enough progress. The world famous scientist (?) that’s running the whole program turns out to be evil.