In this paper we present our current joint work (Georgia Tech - Northwestern University) in developing diagnosis of children's brain cancer and lays down the requirements for fabricating, integrating and testing a bio compactable embedded RF cancer sensor for in vivo monitoring of the recurrence of brain tumor after treatment. The paper presents a detailed literature search on diagnosis of brain tumor. Several techniques used for the treatment and symptoms of recurrence of brain tumor is also presented. A case study done on a group of children is also presented. Through the study the parameters required for a in - vivo sensor understood. Advanced bio materials and conductive polymers are used to fabricate a shape memory bio sensor. The sensors response to a change in temperature and change in PhH of fluid. The sensor fabrication and its applications is in progress. The data collected till date and required improvements will be presented at the conference.