Extrinsic optodes

As a process analytical solution, these extrinsic reactive approaches necessitate an extrinsic optode (see later discussion), an on-line sample conditioning system or an at-Une solution such as a flow injection analysis (FIA) system or other autonomous solutions. Reaction kinetics, post analysis cleanup such as rejuvenating a substrate (optode, immobilized based immunoassays, etc.) among other complexities are additional considerations for these types real-time analysis methods. ... 

Ihble 17-3. values for passive (without immobilization of dyes) and semi-active (active-extrinsic) optodes... 

As already discnssed, intrinsic LIF bioreactor monitoring is the most common application within biopharmaceutical manufacturing. Other extrinsic PAT LIF methods are also possible for biopharmacenticals snch as varions flnorescence immunoassays facilitated by flow injection analysis " or other real-time approaches. As PAT begins to emerge within biopharmaceuticals the wider used of sensitive and precise in-line intrinsic and extrinsic approaches such as optodes and at-line extrinsic methods is likely to occnr. ... 

Fig. 3 Schematic diagram of an extrinsic-type sensor (optode)...

It was mentioned before that fiber-optic chemical and biosensors are broadly classified into two categories extrinsic- and intrinsic-type sensors. In the extrinsic-type sensors, the fiber is acting as a link connecting optical signals to (and from) the active material (medium) positioned at the end of the fiber, such as the Optode case. In the intrinsic-type sensors, the fiber is modified in different ways, through construction of the sensing component, which will be explained next. 

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