You searched for: “oximeter
oximeter (s) (noun), oximeters (pl)
1. An instrument that is used to measure oxygen in something; eudiometer: An oximeter can determine the amount of oxygen in a controlled space, such as an oxygen tank or incubator as well as in the atmosphere.
2. A photoelectric instrument used for measuring the degree of oxygen saturation: An oximeter can estimate the amount of oxygen in a fluid, such as in blood.