Hey Akash! Yes the Mechatronics student can apply for the PSU exam if he matches the eligibility criteria. Mechatronics, which is also called mechatronic engineering, is a multidisciplinary branch of engineering that focuses on the engineering of both electrical and mechanical systems, and also includes a combination of robotics, electronics, computer, telecommunications, systems, control, and product engineering.
The general eligibility for PSU exam are that the applicant should at least be a Graduate. For most of the posts the eligibility is Science Student (B. E., B. Tech., B. Sc.) with 60% marks. Age limit is age 21 to 30 years with some relaxation to SC/ST/OBC Candidates. Hope this may help you.