An apparatus is disclosed for measuring a blood constituent. In a preferred embodiment, the apparatus includes a semipermeable membrane for defining a volume with a flexible membrane disposed on one end and with a light source disposed on an opposite end. The flexible membrane flexes to become the moving...http://www.google.fr/patents/US5079421?utm_source=gb-gplus-shareBrevet US5079421 - Invasive FTIR blood constituent testing
