Sensor assembly

A flexible finger sensor having a finger entrance, a sensor holder at a distal end of the assembly, and a fenestrated region disposed between the finger entrance and the sensor holder. A displacement resistant finger sensor and method of use for reducing motion-related artifacts by mechanical isolation from external forces by providing a resilient sensor body having a digit entrance, a sensor holder, and a fenestrated region between the digit entrance and the sensor holder. The sensor holder maintains sensing elements relative to a user's finger, with said sensing elements being in communication with a monitoring device via a lead wire. The lead wire may extend at a lateral edge of the sensor body. A force to the lead wire may be applied so as to distort the fenestrated region without substantially disturbing the sensing elements relative to the finger surface.