The disclosure includes an apparatus including an elongated assembly, at least a portion of which is sized, shaped, or otherwise configured to be inserted into a human body to measure a physiological parameter at an internal location within the body. The elongated assembly includes an elongated member having a first length and an outer surface, a coil disposed about at least a portion of the elongated member, the coil having a second length, and at least one stand-off member positioned between the outer surface of the elongated member and the coil, where the at least one member is configured to prevent the coil from contacting an optical fiber positioned between the elongated member and the coil.