Reflective Fiber Temperature Probe Based on Localized Surface Plasmon Resonance towards Low-Cost and Wireless Interrogation

Abstract

Reflection fiber temperature sensors functionalized with plasmonic nanocomposite material using intensity-based modulation are demonstrated for the first time. Characteristic temperature optical response of the reflective fiber sensor is experimentally tested using Au-incorporated nanocomposite thin films deposited on the fiber tip, and theoretically validated using a thin-film-optic-based optical waveguide model. By optimizing the Au concentration in a dielectric matrix, Au nanoparticles (NP) exhibit a localized surface plasmon resonance (LSPR) absorption band in a visible wavelength that shows a temperature sensitivity ~0.025%/°C as a result of electron–electron and electron–phonon scattering of Au NP and the surrounding matrix. Detailed optical material properties of the on-fiber sensor film are characterized using scanning electron microscopy (SEM) and focused-ion beam (FIB)-assisted transmission electron microscopy (TEM). Airy’s expression of transmission and reflection using complex optical constants of layered media is used to model the reflective optical waveguide. A low-cost wireless interrogator based on a photodiode transimpedance-amplifier (TIA) circuit with a low-pass filter is designed to integrate with the sensor. The converted analog voltage is wirelessly transmitted via 2.4 GHz Serial Peripheral Interface (SPI) protocols. Feasibility is demonstrated for portable, remotely interrogated next-generation fiber optic temperature sensors with future capability for monitoring additional parameters of interest.

Plasmonic and interferometric optical fiber sensors for electrical system monitoring applications

“…Plasmonic-enabled nanocomposite sensory films exhibit unique optical properties which derive from localized surface plasmon resonances and depend upon the (1) size, (2) shape, and (3) composition of plasmonic nanoparticles as well as the refractive index of the matrix phase. In the case of harsh environment sensing applications, Aunanoparticle based sensing layers have been a dominant class of materials explored with applications including both temperature [27]- [29] and chemical sensing [30]. When applied to temperature sensing applications, the underlying sensing mechanisms primarily concerns an electron-phonon interaction dominated change in the absorptance and therefore the transmittance output of the evanescent wave fiber, with secondary modalities of wavelength shifts in the localized surface plasmon resonance peak (LSPR) being a combined result of real index change in the matrix and free carrier density change of the Au nanoparticles due to thermal expansion.…”

“…As far as the primary mechanism is concerned, an increase in temperature leads to an increase in resistivity of Au, which elevates the temperaturedependent electron-phonon collision frequency, modifying the absorption as a function of wavelength. Detailed discussion of the temperature dependence of plasmonic nanocomposite-based fiber sensors can be found in prior literature for both evanescent wave absorption spectroscopy [27], [28], [31] and reflection probe configurations [29].…”

“…Recent work has placed a particular emphasis on developing portable sensor probes based upon nanocomposite sensing layers, including integrated low-cost interrogators as well as wireless communication systems, capable of integration within electrical assets such as transformers and battery storage systems [28], [29]. Although additional work remains, there has been significant progress towards ruggedizing plasmonic nanocomposite-based fiber sensing probes in recent years.…”

“…Although additional work remains, there has been significant progress towards ruggedizing plasmonic nanocomposite-based fiber sensing probes in recent years. Here we provide an example sensor fabricated in an evanescent wave fiber optic geometry through previously described dip-coating process of sol-gel synthesized Au nanoparticles in silica films to leverage the temperature-dependent absorption mechanisms of matrix-protected nanoparticles (MPN) [27]- [29]. Example microstructure and spectral response of Au LSPR in SiO 2 are shown in Fig.…”

Surface-enhanced Raman spectroscopy hair analysis after household contamination

“…This in turn amplies the Raman signal strength of the colourant molecules adsorbed to the surface of the nanoparticles. 13 Further studies have expanded knowledge of SERS' hair analysis capabilities, such as its ability to detect an underlying colourant in redyed hair, or in its robustness, through the differentiation of 30 distinct dyes by brand, colour, and permanence. 14,15 While the foundation of hair analysis by SERS is today is well known, crime scenes will seldom have the clean conditions available to us in the laboratory setting.…”