2D transition metal carbides or nitrides, known as MXenes, are a new family of 2D materials with close to 30 members experimentally synthesized and dozens more theoretically investigated. Because o...

MXene/Polymer Membranes: Synthesis, Properties, and Emerging Applications

Optical fibre nanowires and microwires offer a variety of enabling properties, including large evanescent fields, flexibility, configurability, high confinement, robustness and compactness. These distinctive features have been exploited in a wealth of applications ranging from telecommunication devices to sensors, from optical manipulation to high Q resonators. In this paper I will review the fundamentals and applications of nanowires and microwires manufactured from optical fibres.

https://iopscience.iop.org/article/10.1088/2040-8978/12/4/043001/pdf

Optical fibre nanowires and microwires: a review

MXene-Enabled Electrochemical Microfluidic Biosensor: Applications toward Multicomponent Continuous Monitoring in Whole Blood

DOI: 10.1002/adom.201801433 Scientific American selects plasmonic sensing as the top 10 emerging technologies of 2018.[15] Almost every single new plasmonic or photonic structure would be explored to test its sensing ability.[16–29] These works tend to report the sensing performance of their own structure. Some declare that their sensitivity breaks the world record. However, there is still a missing literature on what the world record really is, the gap between the experiments and the theoretical limit, as well as the differences between metal-based plasmonic sensors and dielectric-based photonic sensors. To push plasmonic and photonic sensors into industrial applications, an optical sensing technology map is absolutely necessary. This review aims to cover a wide range of most representative plasmonic and photonic sensors, and place them into a single map. The sensor performances of different structures will be distinctly illustrated. Future researchers could plot the sensing ability of their new sensors into this technology map and gauge their performances in this field. In this review, we focus on optical refractive index (RI) sensors with no fluorescent labeling required. We will utilize two parameters to characterize and compare the performance of optical RI sensors: sensitivity to RI change (denoted by symbol SRI) and figure of merit (in short, FoM). For simplicity, we restrict our discussions to bulk RI change, where the change in RI occurs within the whole sample. There is another case where the RI variation occurs only within a very small volume close to the sensor surface. This surface RI sensitivity is proportional to the bulk RI sensitivity, the ratio of the thickness of the layer within which the surface RI variation occurs, and the penetration depth of the optical mode.[6] The bulk RI sensitivity defines the ratio of the change in sensor output (e.g., resonance angle, intensity, or resonant wavelength) to the bulk RI variations. Here, we limit our discussions to the spectral interrogations and the bulk RI sensitivity SRI is given by[3,5–7,30]

Optical Refractive Index Sensors with Plasmonic and Photonic Structures: Promising and Inconvenient Truth

Sensors are becoming increasingly significant in our daily life because of the rapid development in electronic and information technologies, including Internet of Things, wearable electronics, home automation, intelligent industry, etc. There is no doubt that their performances are primarily determined by the sensing materials. Among all potential candidates, layered nanomaterials with two-dimensional (2D) planar structure have numerous superior properties to their bulk counterparts which are suitable for building various high-performance sensors. As an emerging 2D material, MXenes possess several advantageous features of adjustable surface properties, tunable bandgap, and excellent mechanical strength, making them attractive in various applications. Herein, we particularly focus on the recent research progress in MXene-based sensors, discuss the merits of MXenes and their derivatives as sensing materials for collecting various signals, and try to elucidate the design principles and working mechanisms of the corresponding MXene-based sensors, including strain/stress sensors, gas sensors, electrochemical sensors, optical sensors, and humidity sensors. In the end, we analyze the main challenges and future outlook of MXene-based materials in sensor applications.

Ti3C2TX MXene for Sensing Applications: Recent Progress, Design Principles, and Future Perspectives.

Simultaneous voltammetric determination of acetaminophen and isoniazid using MXene modified screen-printed electrode.

A fiber Bragg grating written in a photosensitive microfiber using KrF excimer laser via a uniform phase mask is demonstrated. We have successfully fabricated two Bragg gratings in microfibers having different diameters. In the reflection spectrum of a microfiber Bragg grating (MFBG), we observed two reflection peaks,which agrees with our numerical simulation results. Compared with the fundamental mode reflection, the higher-order reflection mode is more sensitive to the refractive index (RI) variation of the surrounding fluid due to its larger evanescent field. The measured maximum sensitivity is ~102 nm/RIU (RI unit) at an RI value of 1.378 in an MFBG with a diameter of 6 μm.

Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating

Electrochemical microfluidic chip based on molecular imprinting technique applied for therapeutic drug monitoring.

A new cascaded microwave photonic filter that can realize a high Q value is presented. It consists of two infinite impulse response filters based on two active loops. Owing to wavelength conversion employing cross-gain modulation of the amplified spontaneous emission spectrum of the semiconductor optical amplifier in one loop, the interference between the modulated optical signals of different taps from two loops can be avoided, and stable transmission characteristics of the filter can then be achieved. Using this cascaded structure, the free spectral range and Q value can be increased significantly, and tunability can also be realized. Measured results of a high Q of 3338 and a rejection ratio of about 40 dB are achieved.

Ultrahigh-Q microwave photonic filter with Vernier effect and wavelength conversion in a cascaded pair of active loops

We propose an all-optical return-to-zero (RZ) to nonreturn-to-zero (NRZ) format converter utilizing a microfiber knot resonator and an optical bandpass filter. The operation principle is numerically simulated and analyzed. By adjusting the diameter of microfiber knot, the format conversion from RZ to NRZ is successfully demonstrated at different bit rates. The bit-error-rate measurements show the good performance of the proposed format converter.

Yu Zhang

Papers

Simultaneous voltammetric determination of acetaminophen and isoniazid using MXene modified screen-printed electrode.

Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating

Electrochemical microfluidic chip based on molecular imprinting technique applied for therapeutic drug monitoring.

Ultrahigh-Q microwave photonic filter with Vernier effect and wavelength conversion in a cascaded pair of active loops

All-Optical Format Conversion From RZ to NRZ Utilizing Microfiber Resonator