Tilted Fiber Bragg Grating Sensor with Graphene Oxide Coating for Humidity Sensing.

Yung-Da Chiu,Chao-Wei Wu,Chia-Chin Chiang

doi:10.3390/s17092129

Abstract

In this study, we propose a tilted fiber Bragg grating (TFBG) humidity sensor fabricated using the phase mask method to produce a TFBG that was then etched with five different diameters of 20, 35, 50, 55 and 60 μm, after which piezoelectric inkjet technology was used to coat the grating with graphene oxide. According to the experimental results, the diameter of 20 μm yielded the best sensitivity. In addition, the experimental results showed that the wavelength sensitivity was −0.01 nm/%RH and the linearity was 0.996. Furthermore, the measurement results showed that when the relative humidity was increased, the refractive index of the sensor was decreased, meaning that the TFBG cladding mode spectrum wavelength was shifted. Therefore, the proposed graphene oxide film TFBG humidity sensor has good potential to be an effective relative humidity monitor.

Highlights

After it was first developed, most optical fiber was used in telecommunications applications, but in recent years the development of fiber optic sensors has proceeded rapidly, especially with respect to temperature and stress sensors
tilted fiber Bragg grating (TFBG) sensor is twofold: first, the sensitivity of the sensor is increased by reducing the fiber diameters via etching; second, we provide new coating technology used the piezoelectric inkjet can provide a uniform graphene oxide coating and fast processing, allowing it to be used as a humidity sensor
5a coated revealed graphene film was in the form of a sheet, thereby proving thatshown theshown graphene oxide on that graphene film was in the form of a sheet, thereby proving that the graphene oxide was coated on the the graphene film was in the form of a sheet, thereby proving that the graphene oxide was coated the optical fiber sensor (Figure 5b)

Summary

Introduction

After it was first developed, most optical fiber was used in telecommunications applications, but in recent years the development of fiber optic sensors has proceeded rapidly, especially with respect to temperature and stress sensors. Fiber optic sensors for biomedical and home security purposes have been developed in recent years. The mechanism by which such sensors provide measurements is very dependent on changes in the refractive index, such as in the case of LPG gas sensor measurements of CO2 [1] and U-shaped bending-induced interference sensor measurements of glucose solutions [2]. These previously developed sensing methods have not taken into account the impact of environmental humidity. The present study proposes a humidity sensor that could potentially be used to aid other sensors in adjusting to environmental humidity

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