Yunlong Wang

Bio: Yunlong Wang is an academic researcher from Shanghai University. The author has contributed to research in topics: Long-period fiber grating & Polyvinyl alcohol. The author has an hindex of 2, co-authored 3 publications receiving 26 citations.

Humidity Sensor Based on a Long-Period Fiber Grating Coated with Polymer Composite Film

Abstract: We demonstrate a simple and highly sensitive optical fiber relative humidity (RH) sensor based on a long-period fiber grating (LPFG) coated with polyethylene glycol (PEG)/polyvinyl alcohol (PVA) composite films. The resonance wavelength of the LPFG is sensitive to environmental humidity due to the change in effective refractive index caused by the strong surface absorption and desorption of the porous PEG/PVA coatings. The sensor is sensitive in a wide range from 50% to 95% RH, with a highest sensitivity of 2.485 nm/%RH in the range 50-75% RH. The proposed RH sensor has the advantages of compact size, good reversibility, and stability, which makes it attractive for high-humidity environments.

All-fiber mode converter based on fiber grating and multimode interference

Abstract: We propose a novel mode converter (MC) based on multimode interference (MMI). This MC taking advantages of long-period fiber grating and multimode interference, it not only has high conversion efficiency, but also greatly reduces the interference between modes.

Humidity Sensor Based on Long Period Grating Coated with Polyethylene Glycol/Polyvinyl Alcohol

Abstract: A novel relative humidity sensor based on long period grating coated with polyethylene glycol/polyvinyl alcohol film is reported. The sensor has a high sensitivity (1.2902 nm/RH) in RH range of 60% to 95% RH.

Corrosion Sensors for Structural Health Monitoring of Oil and Natural Gas Infrastructure: A Review

Abstract: Corrosion has been a great concern in the oil and natural gas industry costing billions of dollars annually in the U.S. The ability to monitor corrosion online before structural integrity is compromised can have a significant impact on preventing catastrophic events resulting from corrosion. This article critically reviews conventional corrosion sensors and emerging sensor technologies in terms of sensing principles, sensor designs, advantages, and limitations. Conventional corrosion sensors encompass corrosion coupons, electrical resistance probes, electrochemical sensors, ultrasonic testing sensors, magnetic flux leakage sensors, electromagnetic sensors, and in-line inspection tools. Emerging sensor technologies highlight optical fiber sensors (point, quasi-distributed, distributed) and passive wireless sensors such as passive radio-frequency identification sensors and surface acoustic wave sensors. Emerging sensors show great potential in continuous real-time in-situ monitoring of oil and natural gas infrastructure. Distributed chemical sensing is emphasized based on recent studies as a promising method to detect early corrosion onset and monitor corrosive environments for corrosion mitigation management. Additionally, challenges are discussed including durability and stability in extreme and harsh conditions such as high temperature high pressure in subsurface wellbores.

Novel antimicrobial packaging film based on porous poly(lactic acid) nanofiber and polymeric coating for humidity-controlled release of thyme essential oil

Abstract: The objective of this work is to explore a new pathway to develop active packaging materials. Currently, controlled release materials have attracted considerable attention in food packaging applications. In this study, the thyme essential oil (TEO) was loaded in electrospinning porous poly(lactic acid) (PLA) nanofibers and coated with poly(vinyl alcohol)/poly(ethylene glycol) (PVA/PEG) blends for humidity-controlled TEO release. The images of scanning electron microscope displayed uniform pores distributed on the surface of PLA nanofibers. Water contact angle measurement indicated that PVA/PEG coating provided the packaging film with excellent hydrophilicity. ATR-FTIR spectral analysis supported the chemical composition of the films. The antibacterial activities of PLA/TEO/PVA/PEG films against Escherichia coli and Staphylococcus aureus reached ＞99%. Furthermore, the weight loss and firmness of strawberries packaged with this novel film were evaluated. Finally, the in vitro release behaviors of TEO were evaluated and the results demonstrated that the release rate could be controlled by adjusting the humidity (20% RH to 80% RH).

Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers.

Abstract: Polymer composites are favorite materials for sensing applications due to their low cost and easy fabrication. In the current study, composite nanofibers consisting of polyethylene oxide (PEO), oxidized multi-walled carbon nanotubes (MWCNT) and copper oxide (CuO) nanoparticles with 1% and 3% of fillers (i.e., PEO–CuO–MWCNT: 1%, and PEO–CuO–MWCNT: 3%) were successfully developed through electrospinning for humidity sensing applications. The composite nanofibers were characterized by FTIR, XRD, SEM and EDX analysis. Firstly, they were loaded on an interdigitated electrode (IDE), and then the humidity sensing efficiency was investigated through a digital LCR meter (E4980) at different frequencies (100 Hz–1 MHz), as well as the percentage of relative humidity (RH). The results indicated that the composite nanofibers containing 1% and 3% MWCNT, combined with CuO in PEO polymer matrix, showed potent resistive and capacitive response along with high sensitivity to humidity at room temperature in an RH range of 30–90%. More specifically, the PEO–CuO–MWCNT: 1% nanocomposite displayed a resistive rapid response time within 3 s and a long recovery time of 22 s, while the PEO–CuO–MWCNT: 3% one exhibited 20 s and 11 s between the same RH range, respectively.

A novel optical fiber temperature sensor with polymer-metal alternating structure

Abstract: This paper presents a polymer-metal alternating structure (PMAS) optical fiber temperature sensor fabricated using the LIGA electroforming process; the resulting sensor is a new metal-based optical fiber long-period grating temperature sensor. A periodic s-shaped photoresist structure was patterned onto the etched optical fiber, and the electroforming process was used to deposit nickel within the patterned cavity of the photoresist structure. Due to the thermal expansion of the nickel and the strain-optic effect, when the PMAS sensor is heated, the periodic nickel structure on the optical fiber will induce an expansion strain field in the longitudinal direction of the PMAS optical fiber sensor. The temperature experimental results showed that the resonant wavelengths of the PMAS optical fiber sensor exhibited red shifts as the temperature increased from 60 °C −100 °C. The sensitivity of the sensor to changes in temperature in terms of its wavelength shift was −0.541 nm/°C and R2 was 0.937. Therefore, the PMAS optical fiber sensor can be applied for temperature measurements.