modular physiological sensors that are physically and / or electrically configured to share a measurement site for the comfort of the patient and / or to ensure proper operation of the sensors without interference from the other sensors . the modular aspect is realized by providing outer housing shapes that generally conform to other physiological sensors ; mounting areas for attachment of one sensor to another sensor ; providing release liners on the overlapping sensor attachment areas ; and / or providing notches , tabs or other mechanical features that provide for the proper placement and interaction of the sensors .