A unitary sensor is provided that includes a frame upon which electrical and optical components may be disposed and a coating, such as an overmolded coating provided about the frame. The unitary sensor includes one or more diaphragm structures formed from thin regions of the coating material and disposed generally about at least one of the optical components. The diaphragm structure or structures allow the optical components to be separated, such as by application of an opposing force to the lateral sides of the sensor, such that the sensor may be placed on a patient. The sensor may thereby be placed on a patient's finger, toe, and so forth to obtain pulse oximetry or other physiological measurements.