Self-detachable sensors in body cavities such as a contact lens type and a mouthguard are attracted the attention on the preventive medicine. In this paper, a soft contact lens (SCL) sensor for tear sugar monitoring and the mouthguard (MG) sensor with biocompatible materials integrated with Bluetooth wireless module are introduced. The SCL biosensor for tear glucose was fabricated using biocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer and polydimethyl siloxane (PDMS) as the biosensor material. The biosensor consisted of a flexible Pt working electrode and an Ag/AgCl reference/counter electrode. Glucose oxidase (GOD) was immobilized on the sensing region. The SCL sensor allowed to monitor a rabbit tear glucose (normal concentration: 0.11mM). Also, the change of tear glucose induced by the change of blood sugar level was assessed by the oral glucose tolerance test. As another body cavity sensor, the MG thermistor with BLE wireless module was developed using a thermoplastic dental material. The MG sensor has succeeded in telemetry of oral temperature on a smart-watch monitoring display. In the future, the self-detachable body cavity sensors are expected to improve the quality of life.