Fetal Pulse Oximetry and ECG Sensor

A medical device configured to be temporarily secured at a tissue field, such as a fetal skull, via a spiral probe. The spiral probe functions to both secure the sensor in place and provide an electrode for ECG purposes. The spiral probe is non-uniform and includes one or more of a stop element, a cross bar element and a collapsed portion adapted to engage tissue after a predetermined rotation of the probe into the tissue field. The probe diameter can expand with an increase in torque applied to a drive rod, leading to disengagement of the drive rod from the probe. The spiral probe and drive rod may define a detent mechanism whereby upon reaching a predetermined torque the drive rod is disengaged from the probe and freely rotates without further entry of the spiral probe into the tissue field.