How Does Pulse Oximeter Work in Owlet Smart Sock

History of Pulse Oximetry Technology

What is Pulse Oximeter? A pulse oximeter is a device used to measure how much oxygen your blood is carrying. The use of pulse oximeter enables healthcare providers to avoid the traditional way of sticking a needle to obtain blood which would then be measured in a lab. Pulse oximetry process is therefore non-invasive and is fairly accurate.

Pulse Oximetry’s history dates back to 1940s when an American scientist designed the first non-invasive gadget to be used in monitoring a patient’s oxygen saturation (SO2). Glenn Allan Millikan is credited to have been the first scientist to invent the original oximeter in 1940s as an improvement to the works of Karl Matthes, a German physicist who developed O2 saturation meter with red and green filters in 1935.

Current pulse oximeters and specifically the ones you see in hospitals or off-the-shelf finger pulse oximeters use red and infrared LEDs as the original red and green filters were ineffective.

Below is the Owlet’s pulse oximeter which is barely the size of a human’s middle finger and has a curved-shape design to fit well on the baby’s sock.

Owlet Smart Sock Pulse Oximeter Technology on Sock
Owlet Smart Sock Pulse Oximeter Technology on Sock

From 1940s to 2015, pulse oximeters were only limited for use by doctors in hospitals. Owlet, a start-up that was then based in Utah, USA submitted a patent at the US Patents Office for a pulse oximeter that would be inserted in a baby’s sock to be used to monitor the baby’s oxygen level and heartbeat rate. They were successful and that paved way for the first generation Owlet Sock that eventually paved way for a better-designed Owlet Smart Sock 2 that was released to the market in 2017.

Pulse Oximeter LED inserted on a baby's sock

The video below describes the four process that takes place to power pulse oximeter technology in Owlet’s Smart Sock

How Does Pulse Oximeter Works: 3 Key Steps

Below are the steps describing how Pulse oximeter works

  1. Pulse oximeter which comes with an inbuilt clip, similar to a clip used to hang clothes, is inserted on your finger, earlobe or toe with a small pressure to enable it to be in contact with your skin. In Owlet’s Smart Sock, the pulse oximeter is inside the curved part of the smart sock and it comes in contact with the baby’s foot at all times the baby is wearing it.
  2. The pulse oximeter emits a red LED light which passes through your finger, earlobe, toe or baby’s feet to measure oxygen. The beam of light measures the oxygen level in blood and the pulse of your heart or the pulse of your baby’s heart.
  3. Hospital oximeters are fairly accurate with a 2% difference either way. In a normal human being, 89% of the blood should be carrying oxygen as this is the minimum required level needed to keep you healthy. Oxygen saturation level below 95% is still considered normal but anything below 92% may be considered deficient and you may be at risk of hypoxemia. Hypoxemia is a below-normal oxygen level and Mayo Clinic defines this as:

Normal arterial oxygen is approximately 75 to 100 millimeters of mercury (mm Hg). Values under 60 mm Hg usually indicate the need for supplemental oxygen. Normal pulse oximeter readings usually range from 95 to 100 percent. Values under 90 percent are considered low.

From Mayo Clinic

The video below has a more detailed guide on how pulse oximetry works

Below is a short downloadable pulse oximeter brief in PDF format.

Pulse Oximeter for Newborns

The video below describes how a pulse oximeter works to take vital-sign readings of newborns