Fiber-optic sensor for continuous monitoring of fermentation pH

We have developed a fiber-optic chemical sensor for on-line monitoring of fermentation pH. The sensor is based on a covalently bound fluorescent dye immobilized within a water-permeable polymer layer on an optical fiber. Measurements were performed on a portable fluorimeter and employed a ratiometric approach to account for system instabilities. We show that the use of this fiber-optic sensor provides fast, accurate and reliable measurements during E. coli fermentation in a complex medium.