Fiber Surface Plasmon Resonance Research Articles

Wave type fiber SPR sensor for rapid and highly sensitive detection of hyperoside

The fiber surface plasmon resonance (SPR) sensor used for the detection of active ingredients in traditional Chinese medicine has the problems of low sensitivity and difficult specific recognition. This paper proposed a wave type fiber SPR sensor, which reduced the mode of transmitted light through a periodic wave structure and caused concentrated and total reflection of the transmitted beam at the interface between the bent peak cladding and the air. A 50 nm gold film was coated on the surface of the cladding in the wave structure area to form the SPR sensing area. By controlling the width and height of the wave structure to control the total reflection angle of the transmitted light, i.e., the SPR incidence angle, the sensitivity of the fiber SPR sensor was effectively improved to 4972 nm/RIU. Furthermore, HSP90AA protein was modified on the gold film of the sensor to achieve specific detection of hyperoside. The longest single detection time was only 3 minutes, and the detection sensitivity was 0.53 nm/(µg/ml), with a detection limit as low as 0.68µg/ml, which is comparable to liquid chromatography. The proposed wave type fiber SPR sensor is fast in production and has high structural mechanical strength, providing a new approach for the rapid, highly sensitive, and specific detection of active ingredients in traditional Chinese medicine.

Enhanced Surface Plasmon Resonance (SPR) Fiber Optic Sensor for Environmental Monitoring: A Coreless Fiber–Based Design

Enhanced Surface Plasmon Resonance (SPR) Fiber Optic Sensor for Environmental Monitoring: A Coreless Fiber–Based Design

Reflective optical fiber SPR sensor with DNA modification for high-sensitive Hg2+ concentration measurement

A reflective optical fiber surface plasmon resonance (SPR) sensor was proposed to measure the concentration of mercury ions (Hg2+). The specific single-stranded DNA was modified on the optical fiber sensing surface coated with Au film by the combination of covalent bond and charge adsorption. The Hg2+ can mismatch with T-T (thymine-thymine) base pairs in single-stranded DNA to form T-Hg2+-T structure, which led to the change of refractive index in sensing area and the wavelength shift of SPR spectrum. The measurement results showed that when the concentration of Hg2+ increased from 0 μM to 13 μM, the resonance spectrum shifted by 14.26 nm. In the linear range between 1–8 μM, the measurement sensitivity of the sensor could reach 1.51 nm/μM. The limit of detection (LOD) was found to be 0.28 μM. Besides, the sensor showed good stability, selectivity and reusability.

Label-free SPR fiber microfluidic sensor with PDA-MA cross-linked lipase for specific detection of tributyrin

As a precursor to butyric acid and also a short-chain triglyceride, tributyrin plays an important role in repairing small intestinal villi, promoting the absorption and utilization of nutrients, and monitoring human health. The traditional carboxylation functionalization method of optical fiber sensors takes a long time and is complicated to operate. Therefore, we need a sensor with a functional period, high sensitivity, and the ability to quickly detect samples to achieve specific detection of tributyrin. In this paper, based on the chemical cross-linking method of polydopamine-maleic acid (PDA-MA), a novel fiber-optic microfluidic surface plasmon resonance (SPR) sensor was proposed to realize the detection of tributyrin. Compared with the traditional functionalization method, the fixation method of PDA-MA chemical cross-linking method not only shortens the functionalization time, but also increases the sensitivity of the sensor. Experimental results show that the sensitivity of the microfluidic sensor coated with PDA reaches 3392.7 nm/RIU, which is 1.75 times that of the uncoated sensor. The sensor has a sensitivity of 8.22 nm/mM in the range of 0.5–5 mM and a response time of only 8 min at the concentration of 1 mM. In addition, the sample detection error of the sensor is within 12 % in the range of 0.5–5 mM. The proposed sensor offers the advantages of low sample consumption (100 μL), high sensitivity, good selectivity, good repeatability, anti-interference ability, and label-free measurement. The sensor holds promising applications in food safety and health monitoring due to its superior performance.

Sodium-based no-core fiber surface plasmon resonance sensor with high sensitivity and narrow FWHM

Since fiber-optic sensors using noble metal-excited surface plasmon resonance (SPR) effects have encountered bottlenecks in improving performance, we propose a fiber-optic sensor using sodium in combination with a no-core fiber (NCF) to measure both refractive index (RI) and temperature. We deposited sodium thin films on the surface of NCF optical fibers and protected them with polymethyl methacrylate (PMMA) or polydimethylsiloxane (PDMS) for RI sensing or temperature sensing. We performed computational simulations and performance analyses of the sensors using the finite element method, and the results show that the sodium-based SPR sensors have higher sensitivity, wider detection range, and narrower full width at half-maximum (FWHM) than the noble metal SPR sensors. SPR sensors with different sodium film thicknesses have different sensing characteristics, so we can get optical fiber sensors with more flexible transmission characteristics, which helps us arrange sensors more conveniently in practical applications. The simulation and numerical results show that when the sensor is used to measure RI, the average sensitivity of the sensor can reach 7977 nm RIU−1, the maximum sensitivity can reach 23100 nm RIU−1, the narrowest FWHM is 14.23 nm, and the maximum figure of merit (FOM) is 719.42 RIU−1 under different thicknesses of sodium film. The corresponding RI ranges from 1.32 to 1.41. When the temperature measurement range is 0 °C ∼ 100 °C, the average sensitivity can reach 7.86 nm °C−1, the maximum temperature sensitivity can reach 21.1 nm °C−1, and the narrowest FWHM is 17.84 nm. In summary, the proposed sodium-based SPR sensor has flexible and high-performance sensing characteristics, and our research work provides more powerful theoretical support for the application of sodium-based plasma devices.

Smartphone-based selective and sensitive detection of vitamin B1 in synthetic urine using U-bend SPR optical fiber probe

This paper introduces an innovative optical fiber surface plasmon resonance (SPR) biosensor designed for smartphone assistance, aiming at detecting vitamin B1 in synthetic urine. The key novelty lies in the amalgamation of silver nanocoated cysteine with a gold-plated optical fiber probe, fostering efficient detection through the robust electrostatic interaction between negatively charged Cys-capped AgNPs and positively charged vitamin B1 molecules. Notably, this biosensor leverages the smartphone's digital camera capabilities to discern varying color intensities. A self-developed application ensures real-time monitoring of green and red channel intensities in the SPR signal, thereby mitigating the risk of false detections. Moreover, the integration of the fabricated optical fiber probe with the smartphone is achieved through a 3D-printed casing, endowing the biosensor with the advantages of portability, handheld operation, and cost-effectiveness. The proposed U-shaped optical fiber SPR biosensor, coupled with smartphone technology, demonstrates the ability to detect vitamin B1 within the concentration range of 2–10 μM, yielding a commendable R2 value of 0.9973. Experimental findings affirm that this novel biosensor, built on the U-shaped SPR optical fiber architecture and empowered by smartphones, is an economical, uncomplicated, and portable device adept at accurately and efficiently detecting vitamin B1 across a broad concentration spectrum. Its potential applications extend to the area of low-cost biochemical component identification.

Surface plasmon resonance methane sensor based on the D-type photonic quasi-crystal fiber with double-layer films

A high-sensitivity photonic quasi-crystal fiber surface plasmon resonance (PQF-SPR) methane sensor is designed and analyzed. The six-fold Penrose PQF has a D-type structure with two grooves on which TiO2 and Au films are deposited, and methane-sensitive film containing cryptophane-E is coated on the surface of the D-type structure. The characteristics of the sensor are analyzed by the finite element method and the influence of different coating materials (Au-TiO2, Au-MgF2, Au-ITO) on the sensitivity and FOM of the sensor is analyzed and compared. The results show that the PCF-SPR sensor with the dual Au-TiO2 film has better sensing properties. The maximum wavelength sensitivity and average wavelength sensitivity reach 40 nm/% and 34.74 nm/% in the methane concentration range of 0–3.5 % respectively. These properties are significantly better than those of similar sensors reported recently, and the sensor thus has large potential in the development of high-sensitivity and miniaturized methane sensors.

Highly-Sensitive Polymer Optical Fiber SPR Sensor for Fast Immunoassay

A new type of human immunoglobulin G (IgG) sensors based on the surface plasmon resonance (SPR) in the low refractive index (RI) plastic optical fiber (POF) and an antibody immobilization method is presented. A 50-nm-thick gold film was formed on the polished D-shaped fiber surface by magnetron sputtering. The RI response of the POF sensor is 30 049.61 nm/RIU, which is 26.5 times higher than that of single mode fiber (SMF) SPR sensors. The proposed SPR biosensor can be developed by simple and rapid modification of the gold film with 11-mercapto undecanoic acid (MUA). Upon immobilization of the goat anti-human IgG antibody, the resonance wavelength shifts by 11.2 nm. The sensor can be used to specifically detect and quantify the human IgG at concentrations down to 245.4 ng/mL with the sensitivity of 1.327 7 nm per µg/mL, which offers an enhancement of 12.5-fold compared to that of the conventional SMF based SPR sensors. The proposed device may find the potential applications in the case of use at the point of care.

High sensitive optical fiber SPR sensor for label-free detection of Staphylococcus aureus

Optical fiber bacterial sensors have attracted attention in many fields due to their unique advantages. However, it is still difficult to promote its practicality which is mainly subject to their low sensitivity, inferior stability, and reliability. This work reported here an optical fiber surface plasmon resonance (SPR) biosensor enhanced by gold nanoparticles (AuNPs)/Au film coupling for label-free detection the Staphylococcus aureus (S. aureus), while both the gold substrates were successfully biofunctionalized with goat anti-human immunoglobulin G (IgG) as the probe to capture and detect the bacteria. In the experiment, the refractive index（RI） sensitivity of the Multimode-Singlemode-Multimode optical fiber (MSMOF) coated with Au film was improved by 19 % after the AuNPs were homogeneously decorated on the Au film surface. To detect S. aureus by the sensor, the SPR wavelength variation in the transmission spectrum was recorded, and its limit of detection (LOD) was demonstrated experimentally to be about 50 CFU/mL and was obtained theoretically to be 1.18 CFU/mL during its concentration range of 50–108 CFU/mL. Also, it shows great linearity in the range of 102-108 CFU/mL and the sensor exhibits excellent specificity and stability. This kind of SPR-enhanced optical fiber biosensor is fully promising for its applications in biomedicine, food safety, pharmaceuticals, etc.

High-sensitivity optical fiber SPR temperature sensing probe based on Au-PDMS@Au coating

To enhance the sensitivity of polydimethylsiloxane (PDMS)-based optical fiber surface plasmon resonance (SPR) temperature sensing probes, we propose a new prototype with a PDMS@Au sensing layer on the gold (Au) film of the multi-mode fiber (MMF)-single-mode fiber (SMF)-MMF heterojunction structure. This designed probe has improved the temperature sensitivity from −1.26 nm/°C (Au-PDMS) to −2.14 nm/°C (Au-PDMS@Au), maintaining good repeatability and stability. Moreover, the probe can be fabricated with simple procedures at a low cost. Therefore, this probe is a promising tool for temperature sensing in various applications.

High sensitivity fiber SPR sensor based on InSe nanosheets and Au nanoparticles

Surface Plasmon Resonance (SPR) fiber sensors are widely used in the field of biosensing. However, there are still issues of low sensitivity and poor stability in practical detection processes. This paper proposes a highly sensitive fiber SPR sensor based on InSe nanosheets and Au nanoparticles. This paper investigates the enhancement effects of different thicknesses of InSe films inserted between the Au film and the fiber and the adsorption of Au nanoparticles on the Au film surface of the fiber-InSe-Au sensor. The sensitivity of the fiber-InSe-Au sensor reaches 5534.76 nm/RIU, which is 2.71 times higher than the fiber-Au sensor and a 22% improvement compared to the fiber-Au-InSe sensor. The sensitivity of the fiber-InSe-Au-AuNPs sensor further increases to 5853.75, and the FOM reaches 28.11, a 47% improvement compared to the fiber-InSe-Au sensor. Moreover, the enhancement substance is situated within the Au film, which enhances the sensor's stability. Additionally, due to the low biotoxicity and high biocompatibility of Au nanoparticles, the high-performance sensor designed in this study is exceptionally well-suited for biosensing applications.

MnO2-based dual channel surface plasmon resonance fiber sensor for trace glutathione and refractive index detection.

Glutathione (GSH) plays vital role in human biological systems, so its rapid and sensitive detection is necessary for health condition monitoring. In this work, a simple structure for dual channel GSH and refractive index (RI) detection is proposed. By introducing Au-MnO2 thin film coating on the fiber surface for the first time, GSH solution would lead to the dissolution of MnO2, the change in GSH levels could be monitored over a short period in channel 2. For channel 1, ITO-Ag thin film is applied for RI change detection. After optimization, the GSH detection sensitivity reached about -2.361 nm/mM in the range of 0.005-50 mM, and the RI sensitivity reached 1704.252 nm/RIU in the range of 1.331-1.3895 RIU. Channel 1 could also put into GSH detection in the high concentration scale to enlarge the sensor's range and 0.095 nm/mM of sensitivity is acquired within the range of 50-600 mM. With the presence of MnO2 film, the detection sensitivity increased 25.663 times. Neither channel interferes with the operation of the other. Proposed sensor provides stability, high selectivity and elevation in GSH detection sensitivity, which shows great potential for environmental and biological detection field and their applications.

Au-MgF2-Coated Photonic Crystal Fiber Surface Plasmon Resonance Sensor with High FOM

Au-MgF2-Coated Photonic Crystal Fiber Surface Plasmon Resonance Sensor with High FOM

Cascaded dual-channel broadband SPR fiber optic sensor based on Ag and Ag/ZnO/PDMS film structure.

In order to broaden the sensing bandwidth of surface plasmon resonance (SPR) sensors, we propose and demonstrate a dual-channel SPR fiber optic sensor with wide bandwidth. The sensor is fabricated using no-core fiber (NCF), in which the film consists of a silver film and a ZnO film. The sensing characteristics are investigated by simulation and experiment. The resonance wavelength range of the SPR sensor can be significantly tuned by varying the thickness of the ZnO film. In the experiments, a dual-channel SPR sensor that can be used for simultaneous detection of temperature and refractive index was realized by cascading ZnO/Ag film with Ag film. The experimental results show that the two sensing channels are independent without crosstalk. The sensitivity of this sensor is 3512 nm/RIU in the range of 1.333 ∼ 1.385 and 4.6 nm/°C in the range of 0 ∼ 60 °C, which is better than most of the current dual-channel SPR sensors. In addition, the experimental results show that this sensor has good stability in use. The sensor proposed in this work has the advantages of a wide operating wavelength range, simple and compact structure, and high sensitivity. It has a broad application prospect in the simultaneous measurement of refractive index and temperature of liquids.

Optical fiber surface plasmon resonance sensor using electroless-plated gold film for thrombin detection.

This paper describes the simple and label-free detection of thrombin using optical fiber surface plasmon resonance (SPR) sensors based on gold films prepared by the cost-effective method of electroless plating. The plating conditions for simultaneously obtaining gold film on cylindrical core and end surfaces of anoptical fiber suitable for measurement were optimized. The fabricated sensor exhibited a linear refractive index sensitivity of 2150 nm/RIU and 7.136 (a.u.)/RIU in the refractive index of 1.3329-1.3605 interrogated by resonance wavelength and amplitude methods respectively and a single wavelength monitoring method was proposed to investigate the sensing performance of this sensor. Polyadenine diblock and thiolated thrombin aptamers were immobilized on gold nanoparticles and gold films respectively to implement asandwich optical fiber assay for thrombin. The developed optical fiber SPR sensors were successfully used in the determination of thrombin down to 0.56 nM over a wide range from 2 to 100 nM and showed good selectivity for thrombin, which indicated their potential clinical applications for biomedical samples.

Dual Polarized High Sensitivity Photonic Crystal Fiber Surface Plasmon Resonance Sensor Coated with Indium Tin Oxide

Dual Polarized High Sensitivity Photonic Crystal Fiber Surface Plasmon Resonance Sensor Coated with Indium Tin Oxide

RI and temperature sensor based on hybrid sensing mechanism of SPR and MZI using a four-core fiber

A dual-parameter sensor based on a hybrid sensing mechanism of surface plasmon resonance (SPR) and Mach–Zehnder interference (MZI) using a four-core fiber (FCF), is proposed and implemented. The designed sensor is fabricated by cascading a sandwich structure of the FCF, multimode fiber and lead-in/out single-mode fiber. The gold-coated FCF as the critical component, enabling the excitation of the SPR and MZI for measuring refractive index (RI) and temperature. The proposed sensor exhibits a high RI sensitivity of 2091 nm/RIU and a temperature sensitivity of 0.0398 nm/°C. The proposed dual-parameter sensor based on FCF provides a new insight for the design of fiber SPR sensor, which can be used to measure multiple physical parameters in various fields such as biochemistry, gene diagnosis, environmental monitoring, and so on.

Silver-coated hollow fiber surface plasmon resonance sensor for glucose detection with enhanced limit of detection.

A fiber-optic surface plasmon resonance (SPR) biosensor based on a silver-coated hollow fiber (HF) structure for glucose detection is presented. The sensor surface was immobilized with 4-mercaptophenylboronic acid (PMBA) acting as a glucose recognition monolayer. Then, gold nanoparticles (AuNPs) modified with 2-aminoethanethiol (2-AET) and PMBA were introduced onto the sensor surface after glucose was captured to enhance the wavelength shift of the SPR phenomenon excited by the light transmitted in the wall of the HF sensor. Instead of the conventional one-step sensitization pretreatment commonly used in the deposition process of silver films for fiber-optic SPR sensors, a sensitization-activation two-step activation method was adopted in the fabrication of the proposed sensor. Experiments for glucose detection were performed on the fabricated sensors in the concentration range of 1 nM-1 mM. Results showed that the sensor fabricated by the two-step activation method has a much larger shift of resonance wavelength than the sensor fabricated using the one-step sensitization method. The resonance wavelength shift was found to be linear to the logarithm of the concentration in the range of 1 nM-1 mM. The sensor achieved a limit of detection (LOD) of as low as 1 nM, which is at least an order of magnitude lower than that of other fiber-optic sensors for glucose detection reported previously. The presented HF glucose sensor has the potential for biosensing applications and provides a large reference value in the study of optical fiber SPR sensors for biosensing.

Advanced Integration of Glutathione-Functionalized Optical Fiber SPR Sensor for Ultra-Sensitive Detection of Lead Ions.

It is crucial to detect Pb2+ accurately and rapidly. This work proposes an ultra-sensitive optical fiber surface plasmon resonance (SPR) sensor functionalized with glutathione (GSH) for label-free detection of the ultra-low Pb2+ concentration, in which the refractive index (RI) sensitivity of the multimode-singlemode-multimode (MSM) hetero-core fiber is largely enhanced by the gold nanoparticles (AuNPs)/Au film coupling SPR effect. The GSH is modified on the fiber as the sensing probe to capture and identify Pb2+ specifically. Its working principle is that the Pb2+ chemically reacts with deprotonated carboxyl groups in GSH through ligand bonding, resulting in the formation of stable and specific chelates, inducing the variation of the local RI on the sensor surface, which in turn leads to the SPR wavelength shift in the transmission spectrum. Attributing to the AuNPs, both the Au substrates can be fully functionalized with the GSH molecules as the probes, which largely increases the number of active sites for Pb2+ trapping. Combined with the SPR effect, the sensor achieves a sensitivity of 2.32 × 1011 nm/M and a limit of detection (LOD) of 0.43 pM. It also demonstrates exceptional specificity, stability, and reproducibility, making it suitable for various applications in water pollution, biomedicine, and food safety.

Experimental study of SPR sensor performance enhancement by metal oxides

With the widespread application of fiber surface plasmon resonance (SPR) sensors in the field of biochemical sensing, especially in the detection of large molecules such as proteins, the sensitivity of traditional fiber SPR sensors has made it difficult to meet the requirements of detection accuracy in practical applications. This article proposes and proves an effective method for selecting the optimal metal oxide material to improve the sensing performance of SPR sensors. Metal oxides (TiO2 and ZnO) can improve the sensitivity by enhancing the evanescent field of fiber SPR phenomenon. Through simulation, it was found that when the metal oxide film of the composite film sensor maintains the same thickness, the metal oxide with a high effective refractive index (RI) has a better improvement effect on the sensitivity of the SPR sensor. Experimental results show that the maximum RI sensitivity of TiO2 composite film sensors and ZnO composite film sensors in the RI range of 1.333–1.420 is 15,200 nm/RIU and 13,600 nm/RIU, respectively. Compared to silver-based sensors, RI sensitivity has increased by 16.92 % and 4.62 %, respectively. To further verify the enhancement effect of different metal oxides on fiber sensors, another layer of PDMS film is deposited on TiO2 and ZnO films. Within the temperature sensing range, the maximum temperature sensitivity of these two composite film temperature sensors is 4.9 nm/°C and 4.3 nm/°C, respectively. Overall, metal oxides with high RI can improve the sensing performance of fiber optic sensors.