Slab Waveguide and Optical Fibers for Novel Plasmonic Sensor Configurations

Abstract

The use of plasmonic sensor devices often requires replaceable parts and disposable chips for easy, fast and on-site detection analysis. In light of these requests, we propose a novel low-cost surface plasmon resonance sensor platform for possible selective detection of analytes in aqueous solutions. It is based on a Polymethyl methacrylate (PMMA) slab waveguide with a thin gold film on the top surface inserted in a special holder, designed to produce the plasmonic resonance at the gold-dielectric interface. A wide-band light is launched in the PMMA slab waveguide through a trench realized in the holder directly, and illuminated with a PMMA plastic optical fiber (POF) to excite surface Plasmon waves. The output light is then collected by another PMMA POF kept at the end of the slab at an angle of 90° to the trench, and carried to a spectrometer. In this configuration, the trench has been used because a large incident angle is required for surface plasmon resonance excitation. The preliminary results showed that the sensor’s performances make it suitable for bio-chemical applications. The easy replacement of the chip allows for the production of an engineered platform by simplifying the measurement procedures.

An Eco-Friendly Disposable Plasmonic Sensor Based on Bacterial Cellulose and Gold

“…The advantages of this approach, based on an extrinsic POF sensor, is the possibility of remote sensing by two POFs combined with a removable, eco-friendly, and disposable chip sensor for biochemical sensing applications. In fact, as shown in Table 1, the bulk sensitivity and the resolution of the sensor configuration without ILs in the BC paper are very similar to those obtained by other refractive index sensors (several already tested with receptors for the selective detection of analytes) [1,2,3,4,5,6,7,8,9,10,11,12,13,14,22,23,24,25,26,27,28,29], but with all the advantages of an eco-friendly disposable chip.…”

“…From the datasheet of the spectrometer, “ δM meas ” is equal to 1.5 [nm] ( δ ʎmeas ) when the resonance wavelength value is used as measured value (it is the resolution of the spectrometer at FWHM) [11,12,14], whereas it is equal to 0.004 [a.u.] for the sensor based on BC with ILs and it is equal to 0.001 [a.u.]…”

“…More specifically, from the datasheet of Ocean Optics, the spectral emission of the light source ranges from 360 nm to 1700 nm and both the spectrometers are sensitive from 300 nm to 1050 nm with a spectral resolution of the spectrometer of 1.5 nm (full width at half maximum (FWHM)) [11,12,14].…”

“…Many configurations of plasmonic optical fiber sensors have been proposed in order to improve the performances in terms of throughputs, reliability, robustness, and miniaturization [6,7,8,9,10,11,12,13,14]. Usually, the optical fiber sensors are defined as intrinsic and extrinsic.…”

“…In particular, when the interaction of the fiber with the analyzed medium is present, they are defined as intrinsic optical fiber sensors, whereas, when the optical fiber is used only as a mere waveguide allowing the launching of the light to the sensing area and its collection, they are defined as extrinsic optical fiber sensors. The advantage of extrinsic optical fiber sensors are the capability of the remote sensing, typical of the optical fibers, and the possibility of exploiting the input and output fibers only to connect the equipment with the sensor chip, usually disposable, low-cost, and with a better reproducibility from chip to chip [12,13].…”