Optical Fiber Ball Resonator Sensor Spectral Interrogation through Undersampled KLT: Application to Refractive Index Sensing and Cancer Biomarker Biosensing

Optical fiber ball resonators based on single-mode fibers in the infrared range are an emerging technology for refractive index sensing and biosensing. These devices are easy and rapid to fabricate using a CO2 laser splicer and yield a very low finesse reflection spectrum with a quasi-random pattern. In addition, they can be functionalized for biosensing by using a thin-film sputtering method. A common problem of this type of device is that the spectral response is substantially unknown, and poorly correlated with the size and shape of the spherical device. In this work, we propose a detection method based on Karhunen−Loeve transform (KLT), applied to the undersampled spectrum measured by an optical backscatter reflectometer. We show that this method correctly detects the response of the ball resonator in any working condition, without prior knowledge of the sensor under interrogation. First, this method for refractive index sensing of a gold-coated resonator is applied, showing 1594 RIU−1 sensitivity; then, this concept is extended to a biofunctionalized ball resonator, detecting CD44 cancer biomarker concentration with a picomolar-level limit of detection (19.7 pM) and high specificity (30–41%).

Synthesis of Polyaniline Coating on the Modified Fiber Ball and Application for Cr(VI) Removal

In this study, polyaniline (PANI) is prepared by means of chemical oxidization polymerization and directly loaded on the modified fiber ball (m-FB) to obtain macroscale polyaniline/modified fiber ball (PANI/m-FB) composite, and then its removal ability of Cr(VI) is investigated. The effects of different parameters such as contact time, pH value and initial concentration on Cr(VI) removal efficiency are discussed. The experimental results illustrate that the favorable pH value is 5.0 and the maximum removal capacity is measured to be 293.13 mg g−1. Besides, PANI/m-FB composites can be regenerated and reused after being treated with strong acid. The kinetic study indicates that the adsorption procedure is mainly controlled by chemical adsorption. More importantly, the macroscale of composites can avoid secondary pollution efficiently. Benefiting from the low cost, easy preparation in large scale, environmentally friendly, excellent recycling performance as well as high removal ability, PANI/m-FB composites exhibit a potential possibility to remove Cr(VI) from industrial waste water. Graphic Abstract The polyaniline (PANI) was coated on modified fiber ball (m-FB) to remove Cr(VI) in waste water, and this kind of PANI/m-FB composites can avoid secondary pollution efficiently due to its macrostructure. Furthermore, the removal capacity can reach to 291.13 mg/g and can be multiple reused.

Upflow Filtration System Using Fiber-Ball Filter Media for the Treatment of Nonpoint Pollution

Objectives : The objective of this study is to investigate the performance of the fiber-ball media upflow filtration system for non-point pollutants treatment.Methods : The additional air backwashing nozzle were installed between upper and lower fliter media cartridge. The effect of feed SS concentration, surface overflow rate, retention time, head loss on the removal efficiency were investigated respectively. Particle size distribution, SEM, and backwashing effect were also analyzed.Results and Discussion : The operated of upflow filter mean retention time, mean head loss were 1.99 min, 7.2 cm. On condition of SOR 480 m3/m2/day, results indicate that the range of removal efficiency of turbidity and SS were 76.8 ~ 93.21% (mean 88.3%) and 85.4 ~ 97.9% (mean 92.7%), respectively. The effluent turbidity and SS were under 15 NTU, 20 mg/L, respectively.Conclusions : Since turbidity can be continuously monitored in a filtration non-point pollution treatment system, turbidity can be used as a operation factor in evaluating operating conditions. The particle size the effluent larger than the influent was due to bonding, collision and adsorption between particles in the pores of the filter media. SEM analysis showed that after backwashing, very fine particles in the filter medium were not removed but adhered to the fiber yarn and remained. The average recovery rate of fiber-ball media filtration was 88.7%, which is evaluated as excellent in backwashing.

Synthesis of polyaniline coating on the modified fiber ball and application for Cr(VI) removal

In this study, polyaniline (PANI) is prepared by means of chemical oxidization polymerization and directly loaded on the modified fiber ball (m-FB) to obtain macroscale polyaniline/modified fiber ball (PANI/m-FB) composite, and then its removal ability of Cr(VI) is investigated. The effects of different parameters such as contact time, pH value and initial concentration on Cr(VI) removal efficiency are discussed. The experimental results illustrate that the favourable pH value is 5.0 and the maximum removal capacity is measured to be 293.13 mg·g-1. Besides, PANI/m-FB composites can be regenerated and reused after being treated with strong acid. The kinetic study indicates that the adsorption procedure is mainly controlled by chemical adsorption. More importantly, the macroscale of composites can avoid secondary pollution efficiently. Benefiting from the low cost, easy preparation in large scale, environmentally friendly, excellent recycling performance as well as high removal ability, PANI/m-FB composites exhibit a potential possibility to remove Cr(VI) from industrial waste water.