Dear Jisle Mariya,
Yes, you can pursue biomedical engineering. To become eligible for for the UPSC exam you must have completed graduation from any recognized university. It does not matter which stream you have completed your graduation, therefore you can apply for UPSC after your graduation.
The eligibility criteria candidates should be between 21 and 32 years of age as on August 1, 2019 i.e.., they should not have been born earlier than August 2, 1987 and not later than August 1,1998. 
GOOD LUCK!!