Fiber-Optic Chemical Sensors and Biosensors

Porous Silicon‐Based Optical Microsensors for Volatile Organic Analytes: Effect of Surface Chemistry on Stability and Specificity

“…Optical fi bers with chemically responsive sensor heads on their distal end are widely used as remote sensors [41][42][43][44] for detecting vapor-phase organic compounds, [ 42 , 45 ] relative humidity [ 45 ] and aqueous biomolecules. [46][47][48] The small form factor (diameters of a few hundred microns and active regions < 1 mm) allows their use in volume-constrained applications, such as the activated carbon fi ltration cartridge of an air purifying respirator (APR).…”

An Optical Thermometer Based on the Delayed Fluorescence of C70

“…Given the inequalities mentioned above, Equation (2) simplifies to Equation (3), where F T is the quantum yield for triplet formation,…”

“…[1] Given that luminescence can be both excited and measured optically, luminescence-based remote temperature sensors have advantages over contact temperature sensors in applications where electromagnetic noise is strong or it is physically difficult to connect a wire as there is no contact with the medium in the sensing process. [2][3][4] Furthermore, temperature imaging using planar sensors is easily achieved in this way. Additional advantages of a luminescence-based thermometer are the usually fast response and the spatial resolution that can extend from the macroscale (in the case of luminescent paints) down to the nanoscale (such as in fluorescence microscopy).…”

Optofluidic refractometer using resonant optical tunneling effect

“…Inspired by the recent rapid progress of nanotechnology, different near-field mechanisms have been incorporated into the RI measurement, notably surface plasmon resonance ͑SPR͒, [19][20][21] whispering gallery modes of microresonators, 22 photonic bandgap waveguides, 23 photonic crystal fibers, 24 and local coupling of slab waveguides and tapered optical fibers. 25,26 As the near-field effect is confined to a subwavelength region, it intensifies the interaction and thus further improves the sensitivity to a level close to 10 −7 RIU. However, currently the 10 −7 RIU has become a formidable barrier, and none of the available methods is able to go beyond it.…”