In Situ Synthesis of Gold Nanoparticles in Layer-by-Layer Polymeric Coatings for the Fabrication of Optical Fiber Sensors

Abstract

A new method is proposed to tune the interferometric response of wavelength-based optical fiber sensors. Using the nanoparticle in-situ synthesis (ISS) technique, it is possible to synthesize gold nanoparticles (AuNPs) within a pre-existing polymeric thin film deposited at the end-face of an optical fiber. This post-process technique allows us to adjust the optical response of the device. The effect of the progressive synthesis of AuNPs upon polymeric film contributed to a remarkable optical contrast enhancement and a very high tuning capability of the reflection spectra in the visible and near-infrared region. The spectral response of the sensor to relative humidity (RH) variations was studied as a proof of concept. These results suggest that the ISS technique can be a useful tool for fiber optic sensor manufacturing.

Advancements in Polymer-Assisted Layer-by-Layer Fabrication of Wearable Sensors for Health Monitoring

“…Martínez-Hernández et al [107] enhanced the interferometric response of optical fiber sensors by synthesizing AuNPs within a polymeric thin film through the in situ synthesis (ISS) technique. This process involved first constructing a polymeric coating on the optical fiber using a LbL assembly technique, followed by the synthesis of AuNPs directly within this polymeric matrix (Figure 13).…”

Exploring Deposition Techniques and Supramolecular Arrangement in Thin Films for Sensor Applications

“…AuNPs are the most used mainly due to their chemical stability and facile surface functionalization. Stable suspensions for the LbL assembly are usually achieved under reduction by polyelectrolyte stabilization [145,165,[179][180][181], ionic liquids [173], glutathione [175,177], and citrate [89,182]. These stable suspensions can be applied as a component of the LbL assembly combined with opposite-charged polyelectrolytes, nanomaterials, or ions.…”

“…Another approach is the immobilization of the AuCl 4 − anionic precursor onto the LbL assembly to further reduction. This can be carried out by the adsorption of the ionic precursor onto a pre-formed polyelectrolyte multilayer film [179,183] or by mixing AuCl 4 − ions with polyelectrolytes to the LbL assembly [184,185] prior to the reduction.…”

“…Regarding optical sensor applications, the modification of optical fibre aiming LSPR sensing has been recently reported [179,181,182,186]. The LbL technique allows the easy and controllable assembly of AuNPs and AgNPs on the optical fibre surface providing the LSPR signal (plasmon absorption band), which is sensitive to changes in the refractive index of the surrounding medium.…”

Optical Modelling of Planar and Fibre Perovskite Solar Cells

“…This is commonly used in planar PVs and is usually a thin-film layer of a low-loss dielectric material with an intermediate refractive index to match the difference between the air and the electrode. More recently, composite anti-reflection coatings have been proposed, made by synthesizing a transparent dielectric with metal or silica NPs [41][42][43].…”