In situ μ-printed optical fiber-tip CO2 sensor using a photocrosslinkable poly(ionic liquid)

Guang

Advanced Optical Materials

et al. 2019

an integral part of advanced sensing technologies. [1][2][3][4][5][6][7][8][9][10] Various optical principles, such as interference, scattering, total internal reflection, and surface plasmon resonance, are applied in designing fiberoptic (FO) sensors. [11][12][13][14][15][16][17] As an emerging FO device, nanostructured plasmonic FO sensors have attracted much attention due to their superior performance and peculiar properties. [18][19][20][21][22] As nanostructured plasmonic FO sensors feature the characteristics of both traditional FO sensors and plasmonic sensors, they exhibit unique advantages and can be used as powerful biochemical sensing tools or integrated photonic devices. [23][24][25] There have been many reports on the fabrication of plasmonic FO sensors based on metal nanostructures. [26] A simple approach is the use of metal nanoparticles to modify the side or end of the fiber to excite the surface plasmon resonance effect. [27][28][29] Although such methods have the advantages of low cost and simple preparation processes, they present some difficulties in structural control during the fabrication of nanostructures on optical fiber surfaces. In addition, sensors fabricated by these methods usually operate in visible wavebands, which lack an associated communications infrastructure. To overcome these inherent weaknesses, nanoimprint lithography, electronbeam lithography, focused ion beam approaches, reactive ion etching, two-photon polymerization, optical 3D µ-printing, laser erosion direct writing, and other technologies have been proposed and applied to manufacture controllable patterns on the fiber end face. [30][31][32][33][34][35][36][37][38][39][40][41][42] However, these techniques always depend on expensive equipment, which leads to a high-cost and time-consuming production process. As alternative techniques, breath figure methodologies and nanosphere lithography have been employed to fabricate nanostructures on the optical fiber end face. [43,44] Although these methods are cost-effective and produce regular patterns, they have some potential drawbacks that need to be improved. For instance, ceramic ferrule is an essential part of the self-assembly process, which weakens the miniaturization advantage of the fiber probe. In addition, these methods still require professional operation and specialized equipment for the process steps, such as fiber polishing, spin coating, and plasma processing. In general, owing to the high cost, process complexity, and dependence on specialized equipment, hardly any ordinary laboratories fabricate plasmonic FO As an emerging and promising paradigm of nanophotonic "lab-on-a-chip" devices, plasmonic fiber-optic (FO) probes with nanopatterns suffer from high cost and a complex fabrication process, which keep them from becoming the preferred choice for most optical fiber sensing applications. In this paper, a nanopatterned FO probe is demonstrated to be a surface-enhanced Raman spectroscopy substrate and a plasmonic biosensor through theoretical simulations and exp...

Section: Introductionsupporting

confidence: 90%

Simple and Low‐Cost Plasmonic Fiber‐Optic Probe as SERS and Biosensing Platform

Guang

Advanced Optical Materials

et al. 2019

“…An in-house optical exposure setup, as shown in Figure 2 a, was used to fabricate the optical fiber-tip sensors. The setup consists of a high-power UV source (365 nm), a UV-grade digital mirror device (DMD) for generation of optical patterns, projection optics for scaling down optical images, and a digital camera for machine vision metrology [ 28 , 29 , 30 ]. As it is a vitally important step to deposit uniform thin layers of SU-8, an ultrasonic nozzle was utilized to integrate the spray coating process with the optical maskless exposure technology to establish an optical 3D μ-printing technology.…”

Section: Methodsmentioning

confidence: 99%

Optical Fiber-Tip Sensors Based on In-Situ µ-Printed Polymer Suspended-Microbeams

Yao

Ouyang

et al. 2018

Sensors

Self Cite

Miniature optical fiber-tip sensors based on directly µ-printed polymer suspended-microbeams are presented. With an in-house optical 3D μ-printing technology, SU-8 suspended-microbeams are fabricated in situ to form Fabry–Pérot (FP) micro-interferometers on the end face of standard single-mode optical fiber. Optical reflection spectra of the fabricated FP micro-interferometers are measured and fast Fourier transform is applied to analyze the cavity of micro-interferometers. The applications of the optical fiber-tip sensors for refractive index (RI) sensing and pressure sensing, which showed 917.3 nm/RIU to RI change and 4.29 nm/MPa to pressure change, respectively, are demonstrated in the experiments. The sensors and their optical µ-printing method unveil a new strategy to integrate complicated microcomponents on optical fibers toward ‘lab-on-fiber’ devices and applications.

“…Variations in light absorbance, fluorescence, polarization, color, wavelength, or reflectivity are generally recorded by a photodetector and converted into an electrical signal, which is proportional to the concentration and nature of analytes [ 35 ]. Optical devices that rely on reflectometric techniques have been widely reported for the detection of VOCs, such as Fabry–Perot or Mach–Zehnder interferometers and surface plasmon resonance (SPR) sensors [ 36 , 37 ]. These devices commonly make use of optical fibers to direct a light beam from a source to a detector, passing through a sensing membrane.…”

Section: Gas Sensors For Vocs Detectionmentioning

confidence: 99%

“…One of the main benefits of optical gas sensors is their high signal-to-noise ratio or, in other words, their immunity to environmental factors. For this reason, these devices are a good alternative for sensing in complicated environments, with the presence of flammable or explosive gases, very aggressive analytes, or strong electromagnetic fields [ 36 ]. Nonetheless, miniaturization of optical devices has been traditionally tedious and costly to achieve, due to the number of components needed in their operation.…”

Section: Gas Sensors For Vocs Detectionmentioning

confidence: 99%

Advancements in Microfabricated Gas Sensors and Microanalytical Tools for the Sensitive and Selective Detection of Odors

Ollé

Farré-Lladós

Casals‐Terré

2020

Sensors

In recent years, advancements in micromachining techniques and nanomaterials have enabled the fabrication of highly sensitive devices for the detection of odorous species. Recent efforts done in the miniaturization of gas sensors have contributed to obtain increasingly compact and portable devices. Besides, the implementation of new nanomaterials in the active layer of these devices is helping to optimize their performance and increase their sensitivity close to humans’ olfactory system. Nonetheless, a common concern of general-purpose gas sensors is their lack of selectivity towards multiple analytes. In recent years, advancements in microfabrication techniques and microfluidics have contributed to create new microanalytical tools, which represent a very good alternative to conventional analytical devices and sensor-array systems for the selective detection of odors. Hence, this paper presents a general overview of the recent advancements in microfabricated gas sensors and microanalytical devices for the sensitive and selective detection of volatile organic compounds (VOCs). The working principle of these devices, design requirements, implementation techniques, and the key parameters to optimize their performance are evaluated in this paper. The authors of this work intend to show the potential of combining both solutions in the creation of highly compact, low-cost, and easy-to-deploy platforms for odor monitoring.