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Owing to the unique electronic spin properties, nitrogen-vacancy (NV) centers hosted in diamond have emerged as a powerful quantum tool for detecting various physical parameters and biological species. In this work, an optical-fiber quantum probe, configured by chemically modifying nanodiamonds on the surface of a cone fiber tip, is developed. Based on the continuous-wave optically detected magnetic resonance method and lock-in amplification technique, it is found that the sensing performance of probes can be engineered by varying the nanodiamond dispersion concentration and modification duration during the chemical modification process. Combined with a pair of magnetic flux concentrators, the magnetic field detection sensitivity has reached 0.57 nT/Hz

One of the main causes of low back pain (LBP) and degenerative musculoskeletal disorders is intervertebral disc degeneration (IVDD). Inflammation-associated senescence of Human nucleus pulposus cells (HNPCs) plays an essential function in the disease progression of IVDD. Omentin-1 is an adipokine that has been recently reported to have anti-inflammatory potential. In our research, IL-1β was used to simulate the inflammatory environment in the IVDD. We investigated in vitro the effects of Omentin-1 on HNPCs, including the components of senescence, cell cycle and extracellular matrix (ECM) synthesis. The results showed that the addition of Omentin-1 improved IL-1β-induced senescence in HNPCs. G1 phase cell cycle arrest and reduced ECM synthesis in HNPCs. Furthermore, we demonstrated that the effect of Omentin-1 in reducing senescence of HNPCs is dependent on SIRT1. These findings suggest that Omentin-1 plays an important function in protecting HNPCs against senescence and has the potential for IVDD gene target therapy.

Extremely high sensitivity is the long-time pursing goal for the surface plasmon resonance (SPR) sensor, which means the capability to detect analytes with lower concentrations or interactions for smaller biomolecules. It was suggested that a flat dispersion for the plasmon material enables to enhance the sensitivity dramatically. However, the regulation ability of inherent dispersion in natural materials is limited. With the appearance of hyperbolic metamaterials (HMMs), the management of the plasmon materials dispersion becomes possible. In this paper, the HMMs with metal/dielectric multilayer structure are proposed to construct the SPR sensors. Through numerical simulations and theoretical analysis, we find that the flat dispersion in the HMM structure could significantly benefit the sensitivity improvement for HMM-SPR sensors. As a result, the proposed HMM-SPR sensor obtains an ultrahigh sensitivity of 34.00 m/RIU in the experiment, which is one order higher in magnitude than that of the conventional monolayer metallic SPR sensors. Thus, this research shows insight into understanding the dependence of the HMM-SPR sensitivity on dispersion management and provides a practical methodology to develop extremely high-sensitivity SPR sensors based on artificial plasmon materials.

The Vernier effect and harmonic Vernier effect have attracted ever-increasing interest due to their freely tailored spectrum envelope in tunable laser, modulator, and precision sensing. Most explorations have mainly focused on configuring two isolated optical resonators, namely the reference and tunable resonator. However, this configuration requires a stable reference resonator to guarantee robust readout, posing a significant challenge in applications. Here, we discover the coupled-resonators configuration enabling a reference-free envelope modulation to address this problem. Specifically, all parameters of one resonator theoretically span a hypersurface. When the resonator couples to another one, photon coupling merit an escaped solution from the hypersurface, resulting in an envelope modulation independent of reference. We have first experimentally verified this mechanism in a coupled air resonator and polydimethylsiloxane resonator by inserting a semi-transparent 2-mercaptobenzimidazole-modified silver nanowire network. In addition, this novel mechanism provides a new degree of freedom in the reciprocal space, suggesting alternative multiplexing to combine more envelope modulations simultaneously. This study facilitates the fundamental research in envelope multiplexing. More importantly, the combination of silver nanowire network and flexible microcavity experimentally progress the spectral envelope modulation in optoelectronic integration inside resonators.

Armed with the merits of one-dimensional nanostructures (flexibility, high aspect ratio, and anisotropy) and metals (high conductivity, plasmonic properties, and catalytic activity), metal nanowires (MNWs) have stood out as a new class of nanomaterials in the last two decades. They are envisaged to expedite significantly and even revolutionize a broad spectrum of applications related to display, sensing, energy, plasmonics, photonics, and catalysis. Compared with disordered MNWs, well-organized MNWs would not only enhance the intrinsic physical and chemical properties, but also create new functions and sophisticated architectures of optoelectronic devices. This paper presents a comprehensive review of assembly strategies of MNWs, including self-assembly for specific structures, alignment for anisotropic constructions, and patterning for precise configurations. The technical processes, underlying mechanisms, performance indicators, and representative applications of these strategies are described and discussed to inspire further innovation in assembly techniques and guide the fabrication of optoelectrical devices. Finally, a perspective on the critical challenges and future opportunities of MNW assembly is provided.

Benefitting from the excellent characteristics such as low cytotoxicity, functionalization versatility, and tunable fluorescence, nanodiamonds (NDs) have shown enormous application potentials in the biomedical field. Herein, we proposed, for the first time to our best knowledge, to integrate NDs on a plasmonic interface constructed on a side-polished fiber using drop-casting method. The added NDs engineers the plasmonic interface towards improving the sensing field, thus enhancing the sensitivity, which, moreover, is significantly dependent on the number of drop-casting cycles (DCs) and the used concentration of NDs dispersion solution. Experimental results suggest that properly increasing the NDs dispersion concentration is beneficial to obtain a higher sensitivity while using a fewer number of DCs, but the excessive concentration extremely deteriorates the resonance dip. Experimentally, using the optimal 0.2 mg/mL concentration and 3 DCs, we achieve the highest RI sensitivity of 3582 nm/RIU, which shows an enhancement of 73.8% compared to the case without NDs modification. The sensitivity enhancement in biosensing is also proved by employing bovine serum albumin as a demo. The behind mechanism is explored via characterizations and simulations. This work opens up a new application form for NDs, i.e. integrating NDs with a plasmonic interface towards high-performance biosensing.

Silver nanowire (AgNW) based transparent electrode (TE) plays a pivotal role in optoelectronics where TE is generally required to have fine pattern and high performance. Despite the rapid technological advances in either welding or patterning of AgNWs, there are few studies that combine the two processes in a simple and practical manner. Here, aiming to fabricate high-performance patterned AgNW TE, we develop a simplified photolithography that enables both plasmonic nanowelding with low-level UV exposure (20 mW/cm2) and high-resolution micropatterning without photoresist and etching process by conjugating AgNW with diphenyliodonium nitrate (DPIN) and UV-curable cellulose. The cellulose as a binder can effectively enhance plasmonic heating, adhesion, and stability, while the photosensitive DPIN, capable of modulating surface atom diffusion, can boost the plasmonic welding at AgNW junction and induce patterning in AgNW network with Plateau-Rayleigh instability. The fabricated AgNW TE has high figure of merit of up to 1, 000 (3.7 Ω/sq at 90% transmittance) and minimal pattern size down to 3 µm, along with superior robustness. Finally, a flexible smart window with high performance is demonstrated using the patterned and welded AgNW TEs, verifying the applicability of the simplified photolithography technique to optoelectronic devices.

A high-performance surface plasmon resonance (SPR) fiber sensor is proposed with hyperbolic metamaterials (HMMs), nanodiamonds (NDs), and polydimethylsiloxane (PDMS) to enhance the temperature sensitivity and response time. The HMM with tunable dispersion can break through the structural limitations of the optical fiber to improve the refractive index (RI) sensitivity, while NDs and PDMS with large thermo-optic coefficients enable to induce significant RI change under varied thermal fields. The ternary composite endows the sensor with a high temperature sensitivity of -9.021 nm/°C, which is 28.6 times higher than that of the conventional gold film-based SPR sensor. Furthermore, NDs with high thermal conductivity (2200 W/mK) effectively expedite the thermal response of PDMS, which reduces the response time from 80 to 6 s. It is believed that the proposed sensors with high sensitivity, fast response time, and compact size have great potential for applications in industrial production, healthcare, environmental monitoring, etc.

Magnetic field detection exploiting nitrogen-vacancy (NV) centers in diamond has gained increasing attention and development in recent years. Combining diamond NV centers to optical fibers provides a way for achieving magnetic sensors with high integration and portability. Meanwhile, new methods or techniques are urgently desired to improve the detection sensitivity of such sensors. In this paper, we present an optical-fiber magnetic sensor based on the NV ensemble in diamond, and employ the well-designed magnetic flux concentrators to enhance the sensitivity up to 12 pT/Hz1/2, an outstanding level among the diamond-integrated optical-fiber magnetic sensors. The dependence of sensitivity on the key parameters including the size and gap width of the concentrators are investigated by simulations and experiments, based on which the predictions on the further enhancement of sensitivity to fT level are presented.

A tunable near-infrared surface plasmon resonance sensor based on graphene plasmons via electrostatic gating control is investigated theoretically. Instead of the traditional refractive index sensing, the sensor can respond sensitively to the change of the chemical potential in graphene caused by the attachment of the analyte molecules. This feature can be potentially used for biological sensing with high sensitivity and high specificity. Theoretical calculations show that the chemical potential sensing sensitivities under wavelength interrogation patterns are 1.5, 2.21, 3, 3.79, 4.64 nm meV−1 at different wavebands with centre wavelengths of 1100, 1310, 1550, 1700, 1900 nm respectively, and the full width half maximum (FWHM) is also evaluated to be 10, 25.5, 43, 55.5, 77 nm at these different wavebands respectively. It can be estimated that the theoretical limit of detection (LOD) in DNA sensing of the proposed sensor can reach the femtomolar level, several orders of magnitude superior to that of noble metal-based SPR sensors (nanomolar or subnanomolar scale), and is comparable to that of noble metal-based SPR sensors with graphene/Au-NPs as a sensitivity enhancement strategy. The FWHM is much smaller than that of the noble metal-based SPR sensors, making the proposed sensor have a potentially higher figure of merit (FOM). This work provides a new way of thinking to detect in an SPR manner the analyte that can cause chemical potential change in graphene and provides a beneficial complement to refractive index sensing SPR sensors.

A simple and compact sensor based on a hybrid interferometer, which is composed of a cascaded single-mode-multimode-single-mode (SMS) and bending single-mode fiber (BSF) structure, is proposed and investigated. By carefully designing the multimode fiber length of the SMS and the bending diameter of the BSF, the transmittance spectrum features two kinds of dips simultaneously, which show different responses to the surrounding refractive index (RI) and temperature. The SMS structure is only sensitive to the temperature, while the BSF structure is sensitive to both the RI and temperature. Therefore, the simultaneous measurement of the RI and temperature can be achieved by monitoring the two dips induced by the SMS and the BSF, respectively. According to this principle, a cascaded SMS-BSF hybrid sensor is designed, fabricated, and tested. Experimental results show that the sensor possesses an RI sensitivity of 331.71 nm/RIU (from 1.333 to 1.404) and a temperature sensitivity of −1.053 nm/°C (from 30 °C to 70 °C), which is outstanding among the reported results.

In this paper, a simplified simulation method for multimode-no-core-multimode (MNM) fiber structures is developed and demonstrated. The method is based on the mode expansion in the vectorial form, taking account of a complete set of guided modes. The simulated results are in good agreement with the experimental results. Also, it is shown that mode distribution of an input multimode fiber (MMF) is an influence on multimode interference(MMI) in the MNM fiber structure and can be controlled by using a single mode fiber(SMF) segment coupled to it. The proposed method provides an effective way for the designs of multimode-interference(MMI)-based fiber devices, which particularly contain a lot of modes.

A vector magnetometer, composed of a side-polished single-mode-multimode-single-mode fiber structure coated with ferrofluids, is proposed and investigated. The side-polishing of the multimode fiber can expose the evanescent field to the surrounding ferrofluids, whose refractive index in the vicinity of the polished surface can be tuned by both the intensity and direction of the applied magnetic field, thus in turn realizing the magnetic vector sensing. The sensing principles are illustrated in details, and the sensing performances, especially the dependence on the residual thickness (RT) of the side-polished multimode fiber, are well investigated experimentally. It is found that the decrease of the RT can significantly improve the sensitivity to both the magnetic field intensity and the direction, and the highest intensity and direction sensitivities of −0.053 nm/Oe and −5.68 nm/degree have been achieved respectively, when the RT reduces to 50.5 μm. The proposed vector magnetometer, featuring the advantages of simple structure, low cost, and ease of fabrication, can find the potential applications in the fields such as industry, military, and environment.

The ability to engineer microscale and nanoscale morphology upon metal nanowires (NWs) has been essential to achieve new electronic and photonic functions. Here, this study reports an optically programmable Plateau-Rayleigh instability (PRI) to demonstrate a facile, scalable, and high-resolution morphology engineering of silver NWs (AgNWs) at temperatures150 °C within 10 min. This has been accomplished by conjugating a photosensitive diphenyliodonium nitrate with AgNWs to modulate surface-atom diffusion. The conjugation is UV-decomposable and able to form a cladding of molten salt-like compounds, so that the PRI of the AgNWs can be optically programmed and triggered at a much lower temperature than the melting point of AgNWs. This PRI self-assembly technique can yield both various novel nanostructures from single NW and large-area microelectrodes from the NW network on various substrates, such as a nanoscale dot-dash chain and the microelectrode down to 5 μm in line width that is the highest resolution ever fabricated for the AgNW-based electrode. Finally, the patterned AgNWs as flexible transparent electrodes were demonstrated for a wearable CdS NW photodetector. This study provides a new paradigm for engineering metal micro-/nanostructures, which holds great potential in fabrication of various sophisticated devices.

A new concept for portable vector-magnetometer, based on smartphone platform and side-polished-fiber (SPF) integrated with magnetic fluid (MF), is proposed and demonstrated. The magnetometer is designed on a smartphone, which incorporates the functions of light source, detector, and data processing together, and is illuminated and imaged via the SPF. Moreover, thanks to the non-central symmetric structure of the SPF and the magnetic-field-induced anisotropic distribution of the MF around the SPF, the proposed magnetometer is able to detect the intensity and the orientation of magnetic field simultaneously. Experimental results show that the sensitivities of the proposed magnetometer to magnetic field intensity and orientation can reach −0.050 dB/Oe and −0.263 dB/degree, corresponding to the measurement resolutions of 0.336 Oe and 0.064 degree respectively, which are comparable to or even better than that obtained by the traditional platform. Our design can avoid the use of complex and expensive instruments that are employed in the traditional platform. Because of the features of portability, low cost, and highly-sensitive vector measurement, etc., the proposed magnetometer is advantageous for the applications in sensing magnetic vector requiring a portable size and real-time transmission of the measured results.

Biosensors based on surface plasmon resonance (SPR) have shown significant applications in drug screening, environmental monitoring, immunoassay, etc.; however, improving the sensitivity of these biosensors is one of the prime tasks at present. In this study, taking advantage of the special optical and morphological characteristics of MoS2 nanoflowers, we synthesized a sensitivity-improved SPR biosensor by successively depositing MoS2 nanoflowers and gold nanoparticles (AuNPs) on a traditional SPR sensor and then applied this biosensor to the immunoassay of mouse IgG. It was found that the deposition of the MoS2 nanoflowers could improve the bulk refractive index sensitivity from 2212.2 to 2857.2 nm per RIU (RIU: refractive index unit); however, the further addition of AuNPs resulted in a decrease in the bulk refractive index sensitivity to 2149.7 nm per RIU. Moreover, when the proposed biosensor was applied to the IgG immunoassay, a 0.047 nm (μg mL−1)−1 sensitivity of the MoS2–AuNP-modified sensor was achieved, which was ∼3 times that of the unmodified sensor (0.016 nm (μg mL−1)−1). This improvement in the sensitivity of the biosensor towards IgG can be attributed to the flower-like morphology of MoS2 that provides more sites for the loading of AuNPs, thus facilitating the immobilization of a larger amount of IgG antibody on the surface of the sensor. Because of its simple fabrication process and compatibility with the standard bio-activation method of gold surface, the proposed biosensor provides an easily-accessible platform for biological analysis and detection with improved sensitivity.

A high-sensitivity and fast-response fiber-optic plasmonic temperature sensor is developed by coating graphene and polydimethylsiloxane (PDMS) onto an optical-fiber based plasmonic interface. The sensor is composed of a side-polished-fiber for light excitation and readout, a gold layer to excite surface plasmon resonance (SPR), graphene layers to enhance the SPR effect and accelerate the sensing response, and a PDMS layer acting as a thermo-optical responsive material. It is found that the number of graphene layers exhibits positive enhancement on the sensitivity toward the refractive index (RI) until 4 layers, and further increasing the number of layers leads to a decreased sensitivity. The four-layered graphene could improve the sensitivity of the RI sensor by 33% and the temperature sensitivity by 21.9% after overcoating the PDMS layer, increasing the temperature sensitivity from 1.28 nm °C−1 for the SPR sensor with a PDMS layer to only 1.56 nm °C−1 for the graphene–PDMS based sensor. Furthermore, the graphene layers shorten the response time of the temperature sensor by more than one order of magnitude, i.e., from 65 to 6 s. It is believed that the multilayer graphene/PDMS structure can be further exploited for optimizing other temperature sensors in terms of sensitivity and response time.

A new mechanism between the temperature sensitivity and the length ratio of PMMA coating to no-core fiber (NCF) is reported to realize an optical fiber temperature sensor with ultra-high sensitivity and compact size by PMMA-coated no-core fiber. By both theory and experiment, it is found that the sensitivity has a linear response to the length ratio of PMMA coating to NCF rather than the conventional viewpoint that it depends on the length of PMMA. Based on this conclusion and the high thermo-optic coefficient of PMMA, the temperature sensitivity is significantly enhanced as high as -9.582 nm/℃ through a simple, compact, and inexpensive sensor with 5 mm NCF and 3 mm PMMA coating. Our work opens a new avenue of a significant increase in the detection sensitivity of miniaturized fiber temperature sensors.

Cucurbitacin E (CuE) plays an important role in anticancer, antichemical carcinogenesis, and body immunity, etc., and the detection of its concentration is meaningful to pharmacological studies and clinical applications. However, the small molecular weight of CuE makes direct detection difficult through a surface plasmon resonance (SPR) sensor. In this work, we propose a cells-amplified signal strategy at the plasmonic interface, realizing the detection of CuE with ultra-low concentration. The seeded HeLa cells are modified onto the surface of the SPR sensor, and a small amount of CuE can lead to the remarkable morphology change of cells and the release of cell-related substances onto the plamonic interface, thus significantly amplifying the signal. Experimental results show that by using an unmodified SPR sensor with the bulk refractive index sensitivity of 2367.3 nm/RIU (RIU: refractive index unit), there no effective signal can be detected during the CuE concentration range of 0-100 nM; whereas, employing the proposed strategy, the signal for CuE detection can be significantly enhanced, resulting in a high detection sensitivity of 0.6196 nm/nM, corresponding to a limit of detection of 45.2 pM (25.2 pg/mL). The proposed cells-based signal amplifying strategy shows great potential applications in drug screening or bio-sensing to small molecules with low concentration.

A tunable near-infrared surface plasmon resonance sensor based on graphene plasmons

The chaotic light source is one of the most crucial foundations in optical physics studies and photonic devices. The microcavity provides the predominant solution of compact chaotic light sources in integrated photonics. Still, its prefixed feature has severely ruled out access to tuning for meeting the ever-increasing demands of the general-purpose chaotic light source in engineering. Here we report a demonstration of a chaotic light source with a switchable bandpass--band-stop chaotic emission and tunable bandwidth in a spinning microcavity anti-parity-time (anti-$\mathcal{PT}$). system. In addition, the arrangement of anti-$\mathcal{PT}$ microcavity presents several phenomena such as loss-induced chaotic emission and two different chaotic emissions from one microcavity light source. Such advantages offer another possible way to advance multiplex photonic devices and on-chip chaotic light source fabrication. These results provide a promising approach for the tunable chaotic source and serve as tools for applications in secure communications, electromechanical switching, and exploring non-Hermitian physics.

This study was designed to study functions of Circ_0000020 during osteogenic differentiation. First, we used RT-qPCR to detect the expression of Circ_0000020, miR-142-5p and osteogenesis-related genes, whereas western blot analysis detected the expression of osteogenesis markers after the osteogenic differentiation of primary BMSCs isolated from rats. Alkaline phosphatase (ALP) activity and alizarin red Sstaining validated osteoblast phenotypes. Flow cytometry was used to detect cell apoptosis. Sh-Circ_0000020 was used to study the function of Circ_0000020 in osteogenic differentiation of BMSCs. Luciferase assay and RNA immunoprecipitation were used to validate the interaction between Circ_0000020 and miR-142-5p, and BMP2 and miR-142-5p. Co-transfection of miR-142-5p and sh-Circ_0000020 was used to verify the downstream signaling pathway. Circ_0000020 expression was up-regulated during osteogenic differentiation, whereas miR-142-5p expression was significantly decreased. Silencing Circ_0000020 inhibited osteogenic differentiation and promoted apoptosis, and inhibited ALP activity and mineralization ability. Moreover, Circ_0000020 interacts directly with miR-142-5p which binds to the BMP2 3ʹUTR and inhibits its expression. Additionally, co-transfection of miR-142-5p inhibitors and sh-Circ_0000020 rescued down-regulated BMP2, increased the expression osteogenesis-related gene expressions, and thereby rescued the inhibition of osteogenic differentiation induced by Circ_0000020 silencing. Furthermore, co-transfection of miR-142-5p inhibitors and sh-Circ_0000020 reversed Circ_0000020 silencing-induced downregulation of p-Smad1/5/8, Runx2, and Osterix protein levels. Circ_0000020 regulates BMP2 expression through sponging miR-142-5p as ceRNA, thereby positively regulating BMSCs osteogenic differentiation through Circ_0000020/miR-142-5p/BMP2/SMAD-dependent signaling pathway., Graphical abstract

Background Several approaches of fracture reduction and fixation are employed in complex tibial plateau fractures. However, there is a lack of consensus regarding reduction and fixation for fractures to the posterolateral part of the tibial plateau. Hypothesis The combined direct posterior split-gastrocnemius approach may be a choice of the posterior part involved comminuted tibial plateau fractures. Patients and methods We review cases of 216 patients with tibial plateau fracture and subsequent operation from 2012/1/1 to 2017/1/1. Fifty-six cases involved posterolateral plateau damage. For these 56 patients, we use anteromedial and direct posterior split-gastrocnemius approaches or anterolateral and direct posterior split-gastrocnemius approaches to fix the posterolateral and medial or lateral segments. Results From the radiography films, all patients (56/56) achieved a good reduction of the articular surface after surgery (31 patients were anatomic reduction, 25 patients were acceptable reduction). After 12 months follow up, only 2 patients showed poor reduction and no significant difference between

Molybdenum disulfide (MoS2), as a representative layered transition metal dichalcogenide material, possesses great potential applications in highly sensitive detection. In this paper, a sensitivity...

A long-range surface plasmon resonance (LRSPR) sensor with enhanced performance has been theoretically calculated and experimentally investigated for biosensing applications. The LRSPR-based sensor is fabricated by employing a side-polished multimode fiber as a waveguide and MgF2 as a buffer layer beneath a thin silver film for supporting LRSPR excitation. Theoretical optimization based on transfer matrix method and the corresponding validation experiments were carried out in detail. The theoretical and experimental results consistently indicate that the sensing performance parameters of the LRSPR-based sensor are improved with varying degrees in comparison to conventional SPR (CSPR) sensors. It was experimentally achieved that the maximal figure of merit of the LRSPR-based sensor exceeds that of the CSPR sensor by a factor of 1.14. At last the bovine serum albumin (BSA) concentration detection was performed to further confirm the sensitivity enhancement of the optimized sensor in biosensing. This SPR sensor design and development is expected to exert a positive influence on real-time and label-free.

A vector magnetometer, based on a side-polished single-mode-multimode-single-mode fiber structure integrated with ferrofluids, is proposed and investigate. The sensing performance depending on the residual thickness of the side-polished fiber is well investigated experimentally. Comments and questions should be directed to the OSA Conference Papers staff.

It has long been a challenge to develop strain sensors with large gauge factor (GF) and high transparency for a broad strain range, to which field silver nanowires (AgNWs) have recently been applied. A dense nanowire (NW) network benefits achieving large stretchability, while a sparse NW network favors realizing high transparency and sensitive response to small strains. Herein, a patterned AgNW-acrylate composite-based strain sensor is developed to circumvent the above trade-off issue via a novel ultrasonication-based patterning technique, where a water-soluble, UV-curable acrylate composite was blended with AgNWs as both a tackifier and a photoresist for finely patterning dense AgNWs to achieve high transparency, while maintaining good stretchability. Moreover, the UV-cured AgNW-acrylate patterns are brittle and capable of forming parallel cracks which effectively evade the Poisson effect and thus increase the GF by more than 200-fold compared to that of the bulk AgNW film-based strain sensor. As a result, the AgNW-based strain sensor possesses a GF of ∼10,486 at a large strain (8%), a high transparency of 90.3%, and a maximum stretchability of 20% strain. The precise monitoring of human radial pulse and throat movements proves the great potential of this sensor as a measurement module for wearable healthcare systems.

Hyperbolic metamaterials (HMMs) have attracted increasing attentions because of their unique dispersion properties and the flexibility to control the dispersion by changing the components and fractions of the composed materials. In this work, for the first time, we demonstrate a plasmonic sensor based on a side-polished few-mode-fiber coated with a layered of HMM, which is composed of alternating layers of Ag and TiO

A highly sensitive surface plasmon resonance fiber sensor for a vector magnetic field is proposed. The sensor is composed of a half-side gold-coated multimode-single-mode-multimode hetero-core fiber structure encapsulated with ferrofluids. The half-side gold film on the fiber not only produces the surface plasmon resonance, but also breaks the centrosymmetry of the light field in the fiber. Moreover, the magnetic-field-dependent anisotropy of the surrounding ferrofluids makes the sensor sensitive to both the intensity and direction of the magnetic field. Owing to the unique half-side coating configuration and the resulting enhancement of the evanescent field, the sensor can achieve a sensitivity as high as 1008 pm/Oe to the magnetic field intensity. The proposed sensor, possessing advantages such as high sensitivity, ease of fabrication, and low cost, has potential in the detection of a weak vector magnetic field.

High sensitivity and capturing ratio are strongly demanded for surface plasmon resonance (SPR) sensors when applied in detection of small molecules. Herein, an SPR sensor is combined with a novel smart material, namely, MoS2 nanoflowers (MNFs), to demonstrate programmable adsorption/desorption of small bipolar molecules, i.e., amino acids. The MNFs overcoated on the plasmonic gold layer increase the sensitivity by 25% compared to an unmodified SPR sensor, because of the electric field enhancement at the gold surface. Furthermore, as the MNFs have rich edge sites and negatively charged surfaces, the MNF–SPR sensors exhibit not only much higher bipolar-molecule adsorption capability, but also efficient desorption of these molecules. It is demonstrated that the MNF-SPR sensors enable controllable detection of amino acids by adjusting solution pH according to their isoelectric points. In addition, the MNFs decorated on the plasmonic interface can be as nanostructure framework and modified with antibody, which allows for specific detection of proteins. This novel SPR sensor provides a new simple strategy for pre-screening of amino acid disorders in blood plasma and a universal high-sensitive platform for immunoassay.

A novel magnetic field sensing system based on a ferrofluid-coated multimode interferometer (MI) integrated into a fiber-loop ring-down cavity is proposed and demonstrated. The MI is composed of a piece of no-core fiber (NCF) sandwiched by two sections of single-mode fiber. Through appropriately designing the length of the NCF, the ferrofluid-coated MI not only works as the sensing unit but also can help to filter the unwanted amplified spontaneous emission arising from the erbium-doped fiber amplifier in the fiber loop. The proper length of NCF can be determined by simulations. Corresponding experiments are conducted, and the experimental results demonstrate the feasibility of the sensing system. A sensitivity of $- 0.83\,\,\mu \text{s}$ /Oe in the linear region is achieved in experiments.