Abstract: A pulse oximeter sensor with a light source optimized for low oxygen saturation ranges and for maximizing the immunity to perturbation induced artifact. Preferably, a red and an infrared light source are used, with the red light source having a mean wavelength between 700-790 nm. The infrared light source can have a mean wavelength as in prior art devices used on patients with high saturation. The sensor of the present invention is further optimized by arranging the spacing between the light emitter and light detectors to minimize the sensitivity to perturbation induced artifact. The present invention optimizes the chosen wavelengths to achieve a closer matching of the absorption and scattering coefficient products for the red and IR light sources. This optimization gives robust readings in the presence of perturbation artifacts including force variations, tissue variations and variations in the oxygen saturation itself.

Abstract: An improved fetal pulse oximeter sensor. The friction provided on the sensor head surface to engage the fetus is higher than the friction on the back side of the sensor head. Thus, any contact with a maternal surface by the back side of the sensor head is less likely to dislodge the sensor, since the maternal tissues will slide over the sensor head. The portion of the sensor surface in contact with the fetus' head will not move because of the increased friction. The increased friction can be achieved by using two different materials with different coefficients of friction, or by using a smooth surface on the back of the sensor head, and a rough surface on the sensor face.

Abstract: A fetal pulse oximeter sensor in which a sensor head is held against the fetus by the action of a securing means which is remote from the sensor head. The securing means is sufficiently remote so that light detected by the light detector in the sensor head does not scatter through tissue which may be deformed by the securing mechanism. The securing mechanism could deform the tissue by applying pressure, to exsanguinate the tissue, or could attach to the tissue by vacuum, penetration, or glue, etc.

Abstract: A presenting part fetal pulse oximeter sensor which does not penetrate the fetus' skin, and does not rely on a vacuum for attachment is provided. The fetal sensor of the present invention is held in place by pressure applied to the fetus by a number of different mechanisms. In one embodiment, the sensor is held in place against the fetus by a rigid rod, with the pressure being applied by the physician or technician's hand on the rod. This type of a sensor is useful for spot-checking, where continuous monitoring is not needed. In another embodiment, a pre-loaded spring is coupled between the rod and the sensor head to prevent too much pressure being applied by the user.

Abstract: A presenting part fetal pulse oximeter sensor with a securing mechanism for providing tension to a hook or other securing mechanism penetrating the fetal scalp. In one embodiment, a sensor can be secured to the presenting part of the fetus by means of a suture or a hook which penetrates the fetus' scalp. If a suture is used, the ends of the suture are wrapped around a securing member, such as a bar, attached to the back of the sensor. By tying the suture ends around this securing member, the sensor is pressed up against the fetus' scalp and retained in place by virtue of tension provided in the suture between the securing member and the portion of the suture penetrating the fetus' scalp.