Optical Ammonia Sensor for Continuous Bioprocess Monitoring

Abstract

We present an optical ammonia sensor suitable for bioprocess monitoring. A fluorescent dye is physically entrapped in a polyurethane hydrogel forming an emulsion system with vinylterminated polydimethylsiloxane (PDMS). The sensing layer is covered by a hydrophobic porous membrane which excludes hydrophilic substances. Ammonia, diffuses through this barrier and PDMS to the protonated dye, whereby it deprotonates the dye and switches off its emission. Readout is performed with a miniaturized phase fluorimeter combined with optical fibers. Dual-lifetime referencing (DLR) acts as detection method and Egyptian blue as reference material.

Keywords

• ammonia
• optical sensor
• process monitoring
• fluorescent dye