Examples described herein include sensor devices for measuring a parameter of a user. The sensor devices may include a reusable portion (e.g., a sensor). The sensor devices may include one or more weakened portions that may fracture on removal of a portion of the sensor device from the user. Fracturing the weakened portions may expose the reusable portion (e.g., the sensor). Accordingly, the reusable portion may be more readily observed and collected for reuse.