Many Micro-Electro-Mechanical System (MEMS) devices such as gyroscopes, accelerometers, infrared uncooled arrays, radio frequency (RF) resonators etc. require vacuum packaging. In this paper novel MEMS resonators designed as double ended tuning forks (DETF) with pressure sensitive quality factor are presented. The study of different DETF-designs clearly identified the strucutres' ability to monitor the inside cavity pressure of hermetically sealed micro packages. Therefore a new test vehicle for the development and long-time reliability of hermetic wafer bonding technologies can be provided.