Ocean Optics Inc., Dunedin, FL, offers optical oxygen and pH sensors for accurate, real-time in situ measurements in life science, pharmaceutical, biotechnology, and food and beverage processing applications. The sensors use an oxygen-sensitive fluorophore or pH indicator dye trapped in a sol-gel host matrix that can be applied to the tip of an optical fiber, adhesive membrane, or flat substrate. The indicator materials experience a change in optical properties when exposed to specific analytes and electronics then measure the response. For oxygen, the NeoFox Phase fluorometer measures the partial pressure of dissolved or gaseous oxygen; for pH, a miniature fiber-optic spectrometer measures the colorimetric response of the pH dye.