Xiaobing Chen

With the increasing demand for more powerful sensors, rapid development had been achieved. In this paper, a fluorescence(FL) and surface plasmon resonance(SPR) triple channel sensor was designed based on wavelength division multiplexing(WDM). First, ZnS:Cu powder was mixed inside polydimethylsiloxane(PDMS) to detect ultraviolet intensity(UVI) and temperature as channel 1. Second, we coated the thin core fiber(TCF) with 40 nm Ag film and carboxymethyl cellulose (CMC) to detect relative humidity(RH) as channel 2. Third, another part of TCF was coated with 40 nm Ag, 4 nm ZnO film and PDMS also to detect UVI and temperature as channel 3. The detection range and compensation accuracy of UVI, RH and T are 3.74-26.18 mW/cm2, 1.016; 20%-100% RH, 1.022 and 5-41 °C, 1.017. All the channels could be compensated to isolate single variation during simultaneous change. Compared with previous work, the first introduction of fluorescence signal into SPR sensor in this paper achieves three channels integration inside one single fiber structure, and all three parameters could be monitored simultaneously. The advantages of proposed sensor such as high accuracy, stability and multi-parameter simultaneous sensing could be quite useful in future environmental monitoring field.

The ecological environment had encountered severe pollution in recent decades, and the trace metal ions(TMIs) particularly showed high threat to human health, where the ferric ion(Fe ³⁺ ) is one of the most common TMIs. In this paper, a surface plasmon resonance(SPR) fiber sensor was utilized to achieve the detection of trace amount of Fe ³⁺ , which owes to the specific reaction between Ag film and Fe ³⁺ . The change in Fe ³⁺ level could lead to the increase of the refractive index(RI) on the Ag film surface, and such variation would be monitored by the change in resonance wavelength, and a sensitivity of 2.32 nm/lgM was achieved in the range of 8 pM-80 mM with detection limit(LOD) of 7.917 pM. Another detection channel was also designed for the compensation of temperature interference, which used polydimethylsiloxane(PDMS) to elevate the sensitivity towards temperature change. By combining these two channels together, the trace Fe ³⁺ SPR fiber sensor was tested in simultaneous Fe ³⁺ level and temperature change, and the accurate Fe ³⁺ concentration could be acquired after the temperature compensation. The proposed sensor also indicates high stability, fast response and ion selectivity, which shows the potential for future environmental monitoring.

The goal of this study is to develop a computational fluid dynamics (CFD) modeling approach to better estimate the blood flow dynamics in the bundles of the hollow fiber membrane based medical devices (i.e., blood oxygenators, artificial lungs, and hemodialyzers). Three representative types of arrays, square, diagonal, and random with the porosity value of 0.55, were studied. In addition, a 3D array with the same porosity was studied. The flow fields between the individual fibers in these arrays at selected Reynolds numbers (Re) were simulated with CFD modeling. Hemolysis is not significant in the fiber bundles but the platelet activation may be essential. For each type of array, the average wall shear stress is linearly proportional to the Re. For the same Re but different arrays, the average wall shear stress also exhibits a linear dependency on the pressure difference across arrays, while Darcy's law prescribes a power-law relationship, therefore, underestimating the shear stress level. For the same Re, the average wall shear stress of the diagonal array is approximately 3.1, 1.8, and 2.0 times larger than that of the square, random, and 3D arrays, respectively. A coefficient C is suggested to correlate the CFD predicted data with the analytical solution, and C is 1.16, 1.51, and 2.05 for the square, random, and diagonal arrays in this paper, respectively. It is worth noting that C is strongly dependent on the array geometrical properties, whereas it is weakly dependent on the flow field. Additionally, the 3D fiber bundle simulation results show that the three-dimensional effect is not negligible. Specifically, velocity and shear stress distribution can vary significantly along the fiber axial direction.