Optical fiber SPR Pb(2+)sensor with tip-printed Fabry-Perot interferometer for temperature compensation.

Due to the serious biological toxicity and environmental refractory of heavy metal ions, the detection of heavy metal ions in liquids has attracted great attention. A novel fiber optic surface plasmon resonance (SPR) sensor is presented for detecting lead ions (Pb2+) with temperature compensation. The sensitivity of SPR channel to Pb2+ is up to -41.55 nm/μM and the detection limit is 7.05 nM after three parallel experiments by synthesizing Schiff base and fixing it on the sensor surface. Using femtosecond laser-induced two-photon polymerization (TPP) technology, a compact fiber-tip miniature Fabry-Perot interferometer (FPI) was printed at the end of the fiber-optic SPR sensor, thus realizing the temperature measurement in the process of detecting Pb2+. The FPI channel exhibits a linear response to temperature and remains unaffected by Pb2+ concentration, thus facilitating temperature correction. The experimental results also show that the proposed sensor has the advantages of compact structure, easy to prepare, good stability, specificity and repeatability. Therefore, this kind of sensor has great potential in various biochemical test applications, and opens up a new way to prepare compact and flexible optical sensors.

Wang LF ，Zhang YN ，Chen MQ ，Wang Y ，Gong P ，Zhao Y ... -  《-》

Direct electronical readout of surface plasmon resonance biosensor enabled by on-fiber Graphene/PMMA photodetector.

Surface plasmon resonance (SPR) optical fiber sensors are appealing for biomolecular detection due to their inherent characteristics such as flexibility, real-time performance, and high sensitivity. Concurrently, incorporating SPR sensors into wearable devices has emerged as a significant strategy. However, the majority of traditional SPR optical fiber sensors utilize spectrometers for optical readout, which leads to a relatively bulky overall size of the sensing system. Herein, we present the first optical fiber device capable of conducting sensitive SPR measurements and providing direct electronical readout. This has been achieved by integrating a hyperbolic-metamaterial SPR (HMM-SPR) sensor with an on-fiber graphene/PMMA photodetector (oFGPD). The HMM, composed of three pairs of Au/ZrO2, has been employed to develop highly sensitive SPR sensors. The oFGPD, which was constructed by transferring a single layer of graphene onto a tapered fiber region and subsequently covering it with a PMMA protecting film, achieved a high responsivity of 3.42 × 106 A W-1 (at 14.07 pW) and a rapid response time of approximately 90 ms at 1550 nm. More significantly, we have incorporated an SPR sensor based on a side-polished fiber (SPF) into the oFGPD, enabling an electronical readout technique for environmental refractive index (RI) SPR signals in a broad potential spectral range, from visible to near-infrared, all within a more compact device. This integration has been successfully validated in the detection of urea and glucose concentrations in artificial perspiration. This approach provides a novel direction for SPR sensor detection and establishes a solid foundation for their application in wearable technology.

Shen C ，Huang J ，Hu S ，Chen Y ，Zhang L ，Yi C ，Hu X ，Chen Y ，Chen L ，Liu GS ，Luo Y ... -  《-》

Near-infrared SPR biosensor based on photonic crystal fiber for DNA hybridization detection.

Surface plasmon resonance (SPR) sensing technology has been widely used in biometrics, but the weak detection capability and low sensitivity limit the development of SPR biosensors. In this work, we propose to employ the transition metal disulfide (TMD) material MoS2 to induce the SPR effect into the near-infrared band. The aim of this work is to develop a near-infrared sensor capable of quantitatively detecting the concentration of cDNA, which is able to solve the problems of low sensitivity, parameter crosstalk and so on. The results show that the sensitivity of the SPR sensor at infrared wavelengths is 1.69 times higher than that of visible, and the infrared wave is more suitable as an excitation source for the SPR effect because it has a stronger evanescent field. In addition, we have prepared a DNA hybridization sensor that can work in the near-infrared band to detect complementary DNA (cDNA) concentration. Moreover, a combined cascade and parallel strategy realized the temperature and PH detection. The sensor uses the photonic crystal fiber as the platform, silver film as an excitation layer, and MoS2 as a modulation layer. The optimal parameters of the sensor were determined during the experiment, and the three-parameter detection was successfully realized. The experimental results show that the three sensing channels can work independently, and the DNA hybridization probe can achieve selective detection of cDNA with a sensitivity as high as 0.22 nm/(nmol/L). The proposed three-channel DNA hybridization sensor has high sensitivity and accuracy. The innovation of this work is to demonstrate that infrared waves are more suitable to be used as the excitation source of SPR sensors and that the proposed three-channel sensor has a promising future in early diagnosis and biosensing.

Yin Z ，Zhang Z ，Jing X ，Hu L ，Li S ，Li J ... -  《-》

ZnO-Nafion assisted optical fiber dual-SPR biosensor for simultaneous detection of urea and uric acid concentrations.

A novel dual-parameter optical fiber biosensor based on surface plasmon resonance (SPR) for simultaneous measurement of urea and uric acid concentrations is proposed in this paper. Based on the principle of positive and negative electric combination, ZnO nanoparticles is selected as the matrix for immobilizing urease and uricase with selective recognition ability, which can also be used as a sensitizing material to increase the refractive index detection sensitivity of SPR by 22%. Then, Nafion ion exchange membrane was introduced to wrap the urea sensing area to avoid crosstalk caused by the overlap of adjacent sensing areas. The difference in the number of enzymes loaded on ZnO nanoparticles was used to meet the refractive index gap for forming dual SPR detection channels. Experiments indicate that the sensitivity of urea detection is 1.6 nm/mM in the range of 1-9 mM urea concentration. The detection sensitivity of uric acid is 36 nm/mM in the concentration range of 50-500 μM. The detection ability of the sensor to actual biological samples was verified by serum samples, which proved that the sensor has practical application potential and reliable selectivity. It can provide a new idea for the research and development of multi-parameter optical fiber biosensors.

Cheng L ，Guo R ，Zheng W ，He K ，Geng Y ，Liu L ，Ai Q ，He Y ，Zhang YN ，Zhao Y ... -  《-》

[Construction of a 17β-estradiol sensor based on a magnetic graphene oxide/aptamer separating material].

Jin XY ，Chen LY ，Liu YN ，Xie WJ ，Peng HY ... -  《-》