A. A. Shabaneh

Dynamic response of tapered optical multimode fiber coated with carbon nanotubes for ethanol sensing application.

Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol.

Development of a Hydrogen Gas Sensor Using a Double Saw Resonator System at Room Temperature

A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%.

Reflectance Response of Optical Fiber Coated With Carbon Nanotubes for Aqueous Ethanol Sensing

Ethanol is a highly flammable chemical and is widely used for medical and industrial applications. In this paper, optical sensing performance of aqueous ethanol with different concentrations is investigated using multimode fiber coated with carbon nanotubes (CNT). The multimode optical fiber tip is coated with CNT via a drop-casting technique and is annealed at 70 °C to improve the binding of the nanomaterial to the silica fiber. The optical fiber tip and the CNT sensing layer are microcharacterized using field emission scanning electron microscopy, Raman spectroscopy, and X-ray diffraction techniques. The reflectance response of the developed fiber sensor is measured using a spectrophotometer in the optical wavelength range of 500-800 nm. Upon exposure to ethanol with concentration ranges of 5%-80%, the sensor reflectance reduced proportionally. The dynamic response decreased by 4% when the sensor is exposed to ethanol with concentration of 80% in distilled water. It is found that the sensor shows fast response and recovery as low as 38 and 49 s, respectively.

Tapered multimode fiber sensor for ethanol sensing application

Ethanol is a widely used chemical in the industry which can be volatile and flammable. However, the availability of optical sensors for ethanol is still in its maturing stage. In this project, a tapered multimode fiber optic sensor for detection of ethanol with different concentrations in water was developed. The working principle of the sensor is based on absorption spectroscopy in the visible wavelength ranges. The tapered multimode fiber was fabricated using Vytran glass processing workstation to achieve waist diameter and length of 40 μm and 20 mm, respectively. Upon exposure to ethanol concentrations of ranges 5% to 40%, the developed fiber sensor absorbance increases linearly. The sensor shows fast response and recovery as low as 14 s and 27 s, respectively.

Modified plastic optical fiber coated graphene/polyaniline nanocompositefor ammonia sensing

In this paper, a side polished multimode plastic optical fiber gas sensor coated with graphene/polyaniline nanocomposite is developed for ammonia gas sensing application. Graphene/polyaniline nanocomposite is deposited onto side polished plastic optical fiber by drop-casting method. The proposed sensor is exposed to different concentration of ammonia varies from 1% to 0.25 % at room temperature. Absorbance response of the gas sensor is monitored and recorded using spectrophotometer system. The absorbance increase linearly with the increase in the ammonia concentrations. The response and recovery time are 24 s and 71.8 s, respectively.

Reflectance response of optical fiber sensor coated with graphene oxide towards ethanol

In this paper, optical multimode fiber reflectance sensor for ethanol with different concentrations in water was developed. The sensor was coated with graphene oxide (GO) by drop-casting technique. The dynamic response of GO nanostructured thin film coated on optical multimode fiber tip exposed to ethanol liquid was investigated. GO thin film was characterized via Raman microscopy and Scanning Electron Microscopy (SEM). The reflectance decreased by 37% when the fiber tip was exposed to 5% concentration of ethanol in water. The sensor shows fast response and recovery as low as 30 s and 45 s, respectively.

UHF RFID split-ring resonator tag antenna inductively coupled feed for metallic object

In this paper, a split-ring resonator and an inductively coupled feed technique are designed to improve the RFID tag antennas performance. The presented tag antenna consists of two symmetrical C-shaped resonators with strip line in order to feed the radiating split-ring resonator structures by implementing an inductively coupled feed approach placed on the upper surface of Polytetrafluoroethylene substrate. By selecting a proper length and width of spilt-ring resonator structures, along with desirable coupling distance between two symmetrical C-shaped resonators and spilt-ring resonator structures, the input impedance of tag antenna can be obtained, which leads to attain an excellent conjugate match between antenna and IC chip. The proposed feeding technique and spilt-ring resonator structures offer a better performance of RFID tag among antenna size, reflection coefficient, and gain. The gain of the designed tag antenna is -2.272 dB at its operating frequency (916 MHz), the tag antenna is mounted on a square perfect electrical conductor of 200 mm side length, while the thickness of PEC is 1 mm. The simulation results were verified by the presented method via enhancing the performance of tag antennas for metallic object.

Enhancement of fiber-SPR sensor utilizing graphene oxide

A graphene oxide layer deposited on top of a thin gold film of a fiber optic surface plasmon resonance sensor is investigated. Comparison is made on the sensing performance of modified sensor and a standard gold coated fiber optic surface plasmon resonance sensor. The graphene oxide coated sensor shows high sensitivity of approximately 400 nm/RIU to surrounding refractive index when tested with different liquids.