Masimo is an Irvine, California-based manufacturer of noninvasive patient monitoring technologies. The company is best known for its pulse oximetry and it sells more pulse oximeters to hospitals than any other company. Masimo was founded in 1989 by electrical engineer Joe Kiani, who was later joined by fellow engineer Mohamed Diab. Masimo invented measure-through motion and low perfusion pulse oximetry, known as Masimo SET (Signal Extraction Technology).