The SpO₂ finger clip transducer is an absorption design that places two light-emitting diodes (LEDs) on the bottom side of the finger and a photodetector on the top side. The LEDs output two different wavelengths; one red (660 nm peak), and one infrared LED (910 nm peak). The photodiode on the top side faces the LEDs and detects the light that is passed through the translucent part of the finger. The LEDs are alternately flashed many times per second allowing the photodiode to respond to the red and infrared light separately. Well-oxygenated blood is bright red, while poorly oxygenated blood is darker in color. The pulse oximeter determines functional oxygen saturation of arterial hemoglobin from this color difference by calculating the ratio of absorbed red and infrared light as the blood volume at the sensor site fluctuates with each heart beat. Since steady conditions (steady venous blood flow, skin thickness, bone, fingernails, etc.) are not pulsatile, they do not affect the saturation reading.

The Oximeter module input accepts currently offered Human Spo₂ Transducers; Finger Clip (TSD124D) is included, Ear Clip (TSD124B) and Flex Wrap (TSD124C) will also work. SpO₂ output connects to analog CH input via a 1.8 M (6′) cable.

The OXYSSH-SYS utilizes Nonin Medical Inc. pulse oximeter technology which provides accurate and reliable data.

* Note: If using an MP45 two-channel device, only one auxiliary output can be simultaneously recorded in conjunction with the SpO₂ output.