Dual-channel Surface Plasmon Resonance Research Articles

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.

Visible-NIR surface plasmon resonance sensing technology for high precision refractive index detection.

Molybdenum disulfide (MoS2), as a representative transition metal disulfide material, has contributed significantly to the development of plasmonic technology toward the near-infrared (NIR). In this Letter, the physical mechanism of MoS2 excitation of surface plasmon resonance (SPR) in the NIR is investigated, and it is shown that the MoS2 film can induce the resonance dip to move toward the NIR and demonstrate a sensitivity higher than that in the visible band. A dual-channel SPR sensor capable of operating in the visible and NIR bands for refractive index (RI) detection was also prepared using the cascade method. The simulated and experimental results of the sensor show consistency. The experimental results show that the maximum sensitivity of the NIR detection channel is 14600 nm/RIU in the RI range of 1.333-1.420, which is 37% higher than the sensitivity of the visible channel. However, the visible channel has the advantage of a narrow FWHM. Therefore, the proposed cascaded dual-channel RI sensor combines high sensitivity and narrow FWHM. This dual-channel construction method improves the detection level of RI, promotes the development of SPR sensing technology to the NIR band and significantly improves the narrowband problem existing in the previous multi-channel sensing.

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.

Zinc selenide based dual-channel SPR optical biosensor for HIV genome DNA hybridization detection

Simultaneous measurement of human immunodeficiency virus (HIV) genome DNA hybridization and the DNA melting temperature in a prism-based surface plasmon resonance (SPR) biosensor is modeled theoretically using a simple dual-channel construction. The proposed sensor consists of a BK7 prism coated with silver as a plasmonic material. The metal surface is divided into two channels to detect medium refractive index (RI) and temperature. One half is covered with zinc selenide (ZnSe) semiconductor to enhance the hybridization detection sensitivity and to protect silver from oxidation. The other half is covered with polydimethylsiloxane (PDMS) polymer to detect the temperature variations. The proposed sensor is optimized numerically, and the optimum structure provides an excellent sensitivity of 208 deg/RIU, thanks to the use of the ZnSe layer, which is greater than double the reported dual-channel prism-based sensor in thickness. The polymer channel shows high sensitivity to the temperature variations of − 0.125 deg/°C, which is nearly 10 times the response of the RI channel to temperature variations. The data obtained from the polymer channel is used to compensate for the thermal perturbations of the sensing medium RI, and at the same time, to monitor the increments of the temperature in order to avoid reaching the DNA melting temperature. A mathematical expression is provided to consider the effect of the temperature variations on the RI of the sensing medium to get a better accurate detection process. The DNA hybridization detection of HIV is theoretically discussed in detail starting from the preparation of the sensing medium with the different ingredients until the hybridization between probe and complementary target DNA (ct-DNA) molecules.

Modulation of the sensing bandwidth of dual-channel SPR sensors by TiO2 film

Facing the diversity and complexity of the types of parameters to be measured, multi-channel surface plasmon resonance (SPR) fiber sensors provide an excellent solution. However, the sensing bandwidth is a key factor affecting the sensor performance. In this paper, we explore a method to modulate the sensing bandwidth using the TiO2 film. A dual-channel SPR sensor with a wide sensing bandwidth is proposed. In this sensor, no-core fiber (NCF) is used as the sensing probe, and multimode fibers are used for the transmission of optical signals. The sensor has a cascaded composite film structure, the region coated with Ag film as the refractive index sensing region and the region coated with Ag/TiO2/PDMS as the temperature sensing region. The experimental results show that the sensing bandwidth of the sensor varies for different TiO2 coating times. It indicates that the TiO2 film can regulate the sensing bandwidth flexibly. Therefore, to achieve the optimal sensing effect, the TiO2 coating time can be flexibly adjusted according to the RI characteristics of the environment. The maximum sensitivity of this dual-channel sensor is 4.5 nm/°C and 3151 nm/RU when the temperature range is between 10 and 80 °C and the RI range is between 1.333 and 1.385, respectively. In addition, we discuss the repeatability and stability of this dual-channel sensor.

Optical sensing of refractive index (RI) and temperature by dual-channel surface plasmon resonance (SPR) using two single-mode fibers (SMFs) and three multi-mode fibers (MMFs)

A dual-channel surface plasmon resonance (SPR) sensor, based upon a multimode-single mode-multimode-single mode- multimode (MSMSM) fiber structure, is reported for the simultaneous measurement of temperature and refractive index. One channel is coated with an indium tin oxide-silver layer for refractive index sensing, and the channel is coated with Au and cyclohexane layer for temperature sensing. The experiments show that the sensor provides high sensitivity with values of 3379 nm/RIU across the refractive index range from 1.333 to 1.3699 and −3.163 nm/°C from 40 °C to 90 °C. The cross-sensitivity problem is resolved by the dual-wavelength matrix method. Moreover, the proposed sensor has good stability, low cost, and a compact structure and may be employed in biology, chemistry, and environmental testing.

No-core fiber surface plasmon resonance dual-channel sensor for refractive index and temperature sensing with compact structure

To improve the integration of sensors and meet the trend of miniaturization of devices, we propose and demonstrate a compact dual-channel surface plasmon resonance (SPR) fiber sensor for detecting refractive index (RI) and temperature. In this sensor, we chose the simplest structure of optical fiber: no-core fiber (NCF), as the sensing probe. Then the silver film was deposited on the NCF surface using magnetron sputtering to excite the SPR effect. Two sensing channels were constructed on the NCF, one channel deposited with silver film for RI detection, and another channel deposited with PDMS and silver film for temperature detection. Such a construction makes the sensor compact and small. The performance of the proposed sensor is studied theoretically and experimentally. The experiment shows that the maximum sensitivity of the sensor is 3039 nm/RIU and 3.53 nm/°C when the RI ranges from 1.333 to 1.375 and the temperature ranges from 0 °C to 70 °C, respectively. The significant advantage of our proposed sensor is its simple, compact, and easy-to-prepare structure, which opens up a new direction for device miniaturization.

Dual-channel in-fiber SPR sensor for simultaneous and highly sensitive measurement of salinity and temperature.

In this Letter, an in-fiber dual-channel surface plasmon resonance (SPR) sensor is reported that uses polydimethylsiloxane (PDMS)-filled C-type microstructured optical fiber (COF). The COF is made of HF-acid-etched single-sided hole optical fiber (SSHF), and its inner and outer sides are coated with gold film to stimulate SPR. The inner channel is filled with PDMS and acts as the temperature measurement channel, and the outer channel is directly in contact with the salt solution and acts as the salinity measurement channel. Experiments show that the sensor is qualified to detect salinity and temperature simultaneously, and it exhibits a salinity sensitivity of 0.296 nm/‰ in the salinity range of 0-153.32‰ and a high temperature sensitivity of -2.4 nm/°C in the temperature range of 22-44°C. Furthermore, the sensor also enjoys good hysteresis, repeatability, and reversibility in salinity detection. In a word, the high sensitivity, simple preparation, and good integration of the proposed sensor endow it with the potential for deep-sea exploration.

Dual-Channel SPR Sensor Based on MSM Fiber for Detection of Glucose Concentration and Temperature

A dual-channel glucose sensor, based on surface plasmon resonance (SPR), is proposed and experimentally confirmed. The proposed sensor is composed of a single-mode fiber (SMF) sandwiched by two multimode fibers (MMFs). The gold is coated on the cylindrical cladding surface of the optical fiber as a sensing channel to measure the glucose concentration. The other channel is composed of polydimethylsiloxane (PDMS) and gold film to sense the ambient temperature. It has been experimentally verified that the glucose sensor’s concentration sensitivity and temperature sensitivity can reach 2.99 nm/% and −3.580 nm/°C, respectively. The proposed sensor, possessing advantages such as compact structure, excellent sensing performance and the ease of fabrication, has potential applications in biology, chemistry, medicine, etc.

Fiber cladding dual channel surface plasmon resonance sensor based on S-type fiber

Fiber cladding surface plasmon resonance (SPR) sensors have few structures, and a clad SPR sensor based on S-type fiber is proposed in this paper. This new type of fiber cladding SPR sensor was formed by electrofusing an S-shaped structure on the fiber to couple the light in the fiber core to the cladding. In this paper, the effects of fiber parameters on the performance of the sensor were studied by simulation and experiment. Based on the conclusion that the smaller the core diameter is, the closer the working band of the SPR resonance is to long wavelengths, and that the geometric characteristics mean that a multimode fiber can receive the fiber cladding light from a small core diameter few-mode fiber, a dual channel SPR sensor with a double S-type fiber cascade was proposed. In the refractive index detection range of 1.333–1.385 refractive index units (RIU), the resonant working band of channel I is 627.66 nm–759.78 nm, with an average sensitivity of 2540.77 nm/RIU, and the resonant working band of channel II is 518.24 nm–658.2 nm, with an average sensitivity of 2691.54 nm/RIU. The processing method for the S-type fiber cladding SPR sensor is simple, effectively solving the problem of this type of SPR sensor structure and the difficult realization of a dual channel. The sensor is expected to be used in the fields of medical treatment and biological analysis.

Rapid Determination of Methamphetamine and Cocaine in Saliva by Portable Surface Plasmon Resonance (SPR)

Methamphetamine (MA) and cocaine (COC) are among the most abused drugs worldwide. In this study, a portable dual-channel surface plasmon resonance (SPR) biosensor based on an indirect inhibitive immunoassay was developed for the rapid and simultaneous determination of MA and COC in saliva. MA-bovine serum albumin (MA-BSA) and COC-BSA conjugates were prepared as antigens and immobilized on the sensor chip in each channel. Upon contact with the surface-immobilized antigens, MA monoclonal antibody (MA-Ab) or COC monoclonal antibody (COC-Ab) enhanced the SPR signal. The bonding of the antibodies to antigens was inhibited by the presence of MA or COC in the samples. The concentrations of the antigens and antibodies were optimized, and the resulting SPR inhibitive immunoassay exhibited good sensitivity, with limits of detection for MA and COC equal to 0.95 and 3.14 ng·mL−1, respectively. These values are below the legal limits of these drugs for vehicle drivers in China. Furthermore, the suitability of the method was confirmed using saliva from healthy donors, which demonstrated acceptable specificities with satisfactory recoveries. The results indicate that the portable SPR biosensor is facile and rapid for the sensitive determination of abused drugs.

A Dual-Channel Surface Plasmon Resonance Sensor for the Liquid Refractive Index and Temperature Measurement Based on Hollow-Core Fiber

We propose a dual-channel surface plasmon resonance (SPR) sensor based on hollow-core fiber (HCF) for the simultaneous measurement of the liquid refractive index (RI) and ambient temperature. The simultaneous monitoring of two parameters can effectively realize the temperature compensation of liquid RI measurement. One channel is coated with a silver film to sense the liquid RI, the other channel is coated with a gold film and polydimethylsiloxane (PDMS) to sense the ambient temperature, and the cross sensitivity of the multi-parameter measurement is solved using the dual-wavelength matrix method. The sensing performance of the proposed sensor is investigated both theoretically and experimentally, which proves that it can achieve high sensitivity in a relatively wide measurement range. The experiment shows that the liquid RI sensitivity is as high as 2400.079 nm/RIU in the RI range of 1.3333–1.3770, and the temperature sensitivity is −1.29 nm/°C in the temperature range of 40 °C–90 °C. This work provides a new scheme for the multi-parameter measurement, and the proposed sensor has the advantages of simple and compact structure, low cost, wide measurement range and high sensitivity, which promises broad application prospects in the simultaneous monitoring of liquid RI and temperature.

Zeonex-based high sensitivity dual-channel SPR optical fiber sensor for gaseous analytes in terahertz regime

A Zeonex based dual-channel optical fiber Surface Plasmon Resonance (SPR) sensor has been proposed in this paper for gaseous analytes in terahertz regime. The subwavelength porous polymer fiber is surrounded by two semicircular air hole channels and the SPR effect can be excited by the ferroelectric polyvinylidene fluoride (PVDF) layer coated on the inner surface of the channels. A thin dielectric layer is used to enhance the coupling efficiency between the fundamental mode and the surface plasmon polariton mode. Using Finite Element Method, simulation results show that the sensitivity of the sensor can reach 110,000 nm/RIU, which is more than twice the sensitivity proposed by other existing THz optical fiber sensors. Moreover, the dual-channel design and the penetration of terahertz waves facilitate multi-channel detection, making it practical for biomedical and chemical fields.

Micro-Lab on Tip: High-Performance Dual-Channel Surface Plasmon Resonance Sensor Integrated on Fiber-Optic End Facet

It is a challenging and valuable work to realize the simultaneous sensing of two or more parameters at the end of optical fiber. In this paper, we implemented an ultra compact dual-channel surface plasmon resonance (SPR) sensor on fiber-optic end facet. A dual-layer polymer microcap based on different refractive index (RI) films was used to segment a single Cu/TiO2 coated micro-cone on single mode fiber (SMF) end facet for producing a sensing spectrum with two separated SPR dips. The SPR dip (channel-II) generated by Polydimethylsiloxane (PDMS) microcap can reach high sensitivity temperature measurement of 2.935 nm/°C in the range of 30–70 °C, and the SPR dip (channel-I) generated by polyvinyl alcohol (PVA) microcap can achieve high sensitivity humidity measurement of 1.08 nm/%RH in the range of 20%RH-70%RH. Finally, the simultaneous detection of humidity and temperature can be realized by the matrix established by channel-I and channel-II. This is a simple, effective and reproducible micro laboratory on optical fiber end facet for dual parameter sensing.

Dual-Channel Surface Plasmon Resonance–Based Photonic Crystal Fiber Sensor with Metal-Ta2O5 Coating at Near-infrared Wavelength

Dual-Channel Surface Plasmon Resonance–Based Photonic Crystal Fiber Sensor with Metal-Ta2O5 Coating at Near-infrared Wavelength

Side-Polished D-Type Fiber SPR Sensor for RI Sensing With Temperature Compensation

We propose and demonstrate a dual-channel surface plasmon resonance (SPR) sensor based on the side-polished D-type optical fiber, which is available for simultaneous measurement of refractive index (RI) and temperature. The single mode fiber (SMF) is side-polished to remove the fiber cladding and plated a layer of gold film on the polished surface to excite SPR effect. The RI sensing characters are researched by simulation and experiment. The sensitivity increases from 1543 nm/RIU to 6300 nm/RIU as RI increasing from 1.333 to 1.410. Besides, the resonance wavelength red-shifts about 40 nm as the gold film thickness increasing from 40 nm to 60 nm. Based on the above, we design the temperature compensated RI sensor by modifying the side-polished D-type fiber. One half of the side-polished region is applied for RI sensing and the other half is additionally coated a layer of polydimethylsiloxane (PDMS), which is high sensitive to temperature variation, for temperature sensing. In addition, the resonance wavelengths of two sensing channels can be controlled by adjusting the film thickness to avoid crosstalk. In the range from 1.333 to 1.390, the RI sensitivity reaches as high as 2260.1 nm/RIU. In the range from 20 °C to 60 °C, the temperature sensitivity reaches as high as -2.41 nm/°C. Finally, by temperature compensation, the RI measurement accuracy can be greatly improved.

Numerical Analysis of Dual-Parameter Optical Fiber Sensor With Large Measurement Range Based on Surface Plasmon Resonance

Multi parameter measurement and device miniaturization are the development trend of optical fiber sensors. Here we propose a compact dual channel surface plasmon resonance (SPR) fiber sensor which can measure the liquid refractive index (RI) and ambient temperature in real time. This sensor coats metal and polydimethylsiloxane (PDMS) on the side of a no-core D-shaped fiber: the channel for measuring the liquid RI is covered by silver film, and the channel for temperature sensing is covered by gold film and PDMS. The sensing sensitivity is analyzed by finite element method. When the liquid RI is within 1.33~1.44 and the temperature is within 0~180 °C, the corresponding maximum spectral sensitivity is 12530 nm/RIU and −3.465 nm/°C, respectively. The sensor has wide detection range, compact structure and temperature compensation function, which is suitable for environmental monitoring and high-precision sensing.

No-core optical fiber sensor based on surface plasmon resonance for glucose solution concentration and temperature measurement.

The accuracy of the surface plasmon resonance (SPR) optical fiber sensor is affected by the change of ambient temperature. Therefore, we propose a simple dual channel SPR optical fiber sensor, which can measure both glucose concentration and ambient temperature. The proposed sensor is a two-channel structure based on a no-core optical fiber (NCF): one channel is coated with gold film and polydimethylsiloxane (PDMS) to sense the ambient temperature, and the other is coated with silver film to sense glucose concentration. The experimental results show that the sensor's sensitivity for sensing glucose concentration is 2.882 nm / %, and for sensing temperature is -2.904 nm / °C. By monitoring the real-time temperature, the accuracy of glucose concentration detection was improved. The proposed sensor has a simple and compact structure, and it is suitable for sensing glucose solution or other analyte solutions that need temperature compensation.

Dual-channel illumination surface plasmon resonance holographic microscopy for resolution improvement.

Surface plasmon resonance holographic microscopy (SPRHM), combining digital holographic microscopy with surface plasmon resonance (SPR), can simultaneously obtain the amplitude and phase distributions of the reflected beam carrying specimen information in SPR. Due to the decaying length of the surface plasmon wave as large as tens of micrometers, the spatial resolution of SPRHM is lower than that of ordinary optical microscopes. In this work, we propose a scheme to improve the spatial resolution of SPRHM by applying dual-channel SPR excitations. Through the polarization multiplexing technique, two holograms carrying the information of SPR excited in orthogonal directions are simultaneously acquired. Via a numerical reconstruction and filtering algorithm for holograms, the lateral spatial resolution of SPRHM can be effectively enhanced to reach nearly 1 µm at a wavelength of 632.8 nm. This is comparable to the resolution of traditional optical microscopes, while possessing the advantages of wide-field imaging and high measurement sensitivity of SPR.

A Dual-Channel Surface Plasmon Resonance Sensor Based on Dual-Polarized Photonic Crystal Fiber for Ultra-Wide Range and High Sensitivity of Refractive Index Detection

A surface plasmon resonance sensor based on a dual-groove photonic crystal fiber (PCF) for refractive index (RI) sensing with ultra-wide measurement range and high sensitivity is designed and theoretically investigated. The upper and right grooves of the PCF as different sensing channels are coated with Au or Au-TiO2 compound film. The influence of the parameters on the sensing performance of the designed sensor are analyzed. Numerical results show that the maximum wavelength sensitivity (WS) of 6800 nm/RIU with a wavelength resolution of 1.47 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> RIU and maximum amplitude sensitivity (AS) of 5440 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> for the x polarization in the ultra-wide measurement range from 1.25 to 1.43 have been achieved. For y polarization, the proposed sensor has a maximum WS of 13200 nm/RIU and AS of 3465 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> in the detection range from 1.39 to 1.43. The corresponding wavelength resolution is obtained about 7.58 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> RIU. Moreover, the ultra-wide range and high sensitivity of the sensor can be flexibly adjusted by a polarization controller to meet different practical requirements. Therefore, the proposed sensor would be a suitable candidate for medical testing, bio-sensing and environmental monitoring.