Fabrication and characterization of the surface plasmon resonance (SPR) based three channel fiber optic sensor for
multiple parameter sensing have been carried out. Three probes have been prepared on a single fiber by coating silver,
gold and copper along with one high index titanium oxide on three unclad well separated portions of the fiber
respectively. SPR spectra have been recorded for aqueous sucrose solutions of varying refractive indices. The sensor
relies on wavelength interrogation technique. To verify the results, simulations have been carried out using a multilayer
model and geometrical optics. The experimental and simulated results have been found to match qualitatively. The
present sensor can simultaneously sense multiple parameters/analytes at a single platform.
A design of SPR based fiber optic ethanol biosensor is presented by using enzyme alcohol dehydrogenase and nicotinic
acid. The sensing probe is fabricated with the coating of 40 nm thin film of silver metal and immobilization of alcohol
dehydrogenase and nicotinic acid by gel entrapment method over unclad core of a multimode optical fiber. The SPR
spectra of ethanol samples of concentrations ranging from 0 mM to 10 mM prepared in buffer have been recorded. The
sensor works on the spectral interrogation technique and operates in the visible range of the spectrum. The SPR curves
are blue shifted with the increasing concentration of ethanol and the sensitivity of the sensor decreases with the
increasing concentration of ethanol. The sensor has many advantages such as fast response, stability, small probe size,
low cost and can be used for remote/online monitoring.
The nano-textured surface of black silicon can be used as a surface-enhanced Raman scattering (SERS) substrate. Sputtered gold films showed increasing SERS sensitivity for thicknesses from 10 up to 300 nm, with sensitivity growing nonlinearly from around 50 nm until saturation at 500 nm. At 50 nm, a cross over from a discontinuous to a fully percolated film occurs as revealed by morphological and electrical measurements. The roughness of the Au coating increases due to formation of nanocrystallites of gold. Structural characterization of the black- Si needles and their surfaces revealed presence of silicon oxide and fluoride. The sharpest nano-needles had a tip curvature radius of ~10 nm. SERS recognition of analyte using molecular imprinted gels with tetracycline molecules of two different kinds is demonstrated.
We report the fabrication and characterization of surface plasmon resonance (SPR) based optical fiber riboflavin/vitamin B2 sensor using combination of colloidal crystal templating and molecularly imprinted gel. The sensor works on spectral interrogation method. The operating range of the sensor lies from 0 μg/ml to 320 μg/ml, the suitable amount of intakes of riboflavin recommended for different age group. The SPR spectra show blue shift with increasing concentration of riboflavin, which is due to the interaction of riboflavin molecule over specific binding sites caused by molecular imprinting. The present sensor has many advantageous features such as fast response, small probe size, low cost and can be used for remote/online monitoring.
Surface plasmon resonance (SPR) based fiber optic sensor has been studied for multichannel and multianalyte sensing.
Simulations have been carried out for a fiber optic sensor having two sensing regions coated with silver and gold for
multichannel and multianalyte sensing. The simulated results have been obtained for different combinations of refractive
indices of the samples around the probes. To support simulations optical fiber SPR probes with two sensing regions
coated with silver and gold have been fabricated. SPR spectra for these sensors have been recorded for aqueous sucrose
solutions of varying refractive indices. The refractive index of the liquid samples around both the gold and silver coated
regions was kept the same to see the potential of SPR based fiber optic multichannel sensing, while it was kept different
for studies related to multianalyte sensing. Both the theoretical and experimental results match qualitatively. The SPR
resonance wavelengths for gold and silver being different, these sensors can be utilized for both multichannel and