Recent Progress in Fiber Optofluidic Lasing and Sensing

AbstractFiber optofluidic laser (FOFL) integrates optical fiber microcavity and microfluidic channel and provides many unique advantages for sensing applications. FOFLs not only inherit the advantages of lasers such as high sensitivity, high signal-to-noise ratio, and narrow linewidth, but also hold the unique features of optical fiber, including ease of integration, high repeatability, and low cost. With the development of new fiber structures and fabrication technologies, FOFLs become an important branch of optical fiber sensors, especially for application in biochemical detection. In this paper, the recent progress on FOFL is reviewed. We focuse mainly on the optical fiber resonators, gain medium, and the emerging sensing applications. The prospects for FOFL are also discussed. We believe that the FOFL sensor provides a promising technology for biomedical analysis and environmental monitoring.

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A Solution to Ambiguities in Position Estimation for Solenoid Actuators by Exploiting Eddy Current Variations

Sensors ◽

10.3390/s20123441 ◽

2020 ◽

Vol 20 (12) ◽

pp. 3441 ◽

Cited By ~ 1

Author(s):

Niklas König ◽

Matthias Nienhaus

Keyword(s):

Eddy Current ◽

Signal To Noise Ratio ◽

Low Cost ◽

High Sensitivity ◽

Position Estimation ◽

High Signal ◽

Wide Field ◽

Fusion Algorithm ◽

Case Scenario ◽

Position Detection

Position estimation techniques for solenoid actuators are successfully used in a wide field of applications requiring monitoring functionality without the need for additional sensors. Most techniques, which also include standstill condition, are based on the identification of the differential inductance, a parameter that exhibits high sensitivity towards position variations. The differential inductance of some actuators shows a non-monotonic dependency over the position. This leads to ambiguities in position estimation. Nevertheless, a unique position estimation in standstill condition without prior knowledge of the actuator state is highly desired. In this work, the eddy current losses inside the actuator are identified in terms of a parallel resistor and are exploited in order to solve the ambiguities in position estimation. Compared to other state-of-the-art techniques, the differential inductance and the parallel resistance are estimated online by approaches requiring low implementation and computation effort. Furthermore, a data fusion algorithm for position estimation based on a neural network is proposed. Experimental results involving a use case scenario of an end-position detection for a switching solenoid actuator prove the uniqueness, the precision and the high signal-to-noise ratio of the obtained position estimate. The proposed approach therefore allows the unique estimation of the actuator position including standstill condition suitable for low-cost applications demanding low implementation effort.

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Mid-infrared photoacoustic gas monitoring driven by a gas-filled hollow-core fiber laser

Scientific Reports ◽

10.1038/s41598-021-83041-2 ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Yazhou Wang ◽

Yuyang Feng ◽

Abubakar I. Adamu ◽

Manoj K. Dasa ◽

J. E. Antonio-Lopez ◽

...

Keyword(s):

Fiber Laser ◽

Signal To Noise Ratio ◽

High Sensitivity ◽

Laser Source ◽

High Signal ◽

Mid Infrared ◽

Raman Fiber Laser ◽

Custom Made ◽

Core Fiber ◽

Detection Technologies

AbstractDevelopment of novel mid-infrared (MIR) lasers could ultimately boost emerging detection technologies towards innovative spectroscopic and imaging solutions. Photoacoustic (PA) modality has been heralded for years as one of the most powerful detection tools enabling high signal-to-noise ratio analysis. Here, we demonstrate a novel, compact and sensitive MIR-PA system for carbon dioxide (CO2) monitoring at its strongest absorption band by combining a gas-filled fiber laser and PA technology. Specifically, the PA signals were excited by a custom-made hydrogen (H2) based MIR Raman fiber laser source with a pulse energy of ⁓ 18 μJ, quantum efficiency of ⁓ 80% and peak power of ⁓ 3.9 kW. A CO2 detection limit of 605 ppbv was attained from the Allan deviation. This work constitutes an alternative method for advanced high-sensitivity gas detection.

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Methods for Voltage-Sensitive Dye Imaging of Rat Cortical Activity With High Signal-to-Noise Ratio

Journal of Neurophysiology ◽

10.1152/jn.01169.2006 ◽

2007 ◽

Vol 98 (1) ◽

pp. 502-512 ◽

Cited By ~ 81

Author(s):

Michael T. Lippert ◽

Kentaroh Takagaki ◽

Weifeng Xu ◽

Xiaoying Huang ◽

Jian-Young Wu

Keyword(s):

Dynamic Range ◽

Signal To Noise Ratio ◽

Field Potential ◽

High Sensitivity ◽

High Dynamic Range ◽

High Signal ◽

Blue Dye ◽

Voltage Sensitive Dye ◽

Imaging Device

We describe methods to achieve high sensitivity in voltage-sensitive dye (VSD) imaging from rat barrel and visual cortices in vivo with the use of a blue dye RH1691 and a high dynamic range imaging device (photodiode array). With an improved staining protocol and an off-line procedure to remove pulsation artifact, the sensitivity of VSD recording is comparable with that of local field potential recording from the same location. With this sensitivity, one can record from ∼500 individual detectors, each covering an area of cortical tissue 160 μm in diameter (total imaging field ∼4 mm in diameter) and a temporal resolution of 1,600 frames/s, without multiple-trial averaging. We can record 80–100 trials of intermittent 10-s trials from each imaging field before the VSD signal reduces to one half of its initial amplitude because of bleaching and wash-out. Taken together, the methods described in this report provide a useful tool for visualizing evoked and spontaneous waves from rodent cortex.

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Wind Turbine Noise Reduction from Seismological Data

10.5194/egusphere-egu21-4907 ◽

2021 ◽

Author(s):

Janis Heuel ◽

Wolfgang Friederich

Keyword(s):

Signal To Noise Ratio ◽

Low Cost ◽

Computational Cost ◽

Noise Signal ◽

Noise Model ◽

Threshold Function ◽

High Signal ◽

Time Data ◽

Negative Effects ◽

Before And After

Over the last years, installations of wind turbines (WTs) increased worldwide. Owing to negative effects on humans, WTs are often installed in areas with low population density. Because of low anthropogenic noise, these areas are also well suited for sites of seismological stations. As a consequence, WTs are often installed in the same areas as seismological stations. By comparing the noise in recorded data before and after installation of WTs, seismologists noticed a substantial worsening of station quality leading to conflicts between the operators of WTs and earthquake services.In this study, we compare different techniques to reduce or eliminate the disturbing signal from WTs at seismological stations. For this purpose, we selected a seismological station that shows a significant correlation between the power spectral density and the hourly windspeed measurements. Usually, spectral filtering is used to suppress noise in seismic data processing. However, this approach is not effective when noise and signal have overlapping frequency bands which is the case for WT noise. As a first method, we applied the continuous wavelet transform (CWT) on our data to obtain a time-scale representation. From this representation, we estimated a noise threshold function (Langston & Mousavi, 2019) either from noise before the theoretical P-arrival (pre-noise) or using a noise signal from the past with similar ground velocity conditions at the surrounding WTs. Therefore, we installed low cost seismometers at the surrounding WTs to find similar signals at each WT. From these similar signals, we obtain a noise model at the seismological station, which is used to estimate the threshold function. As a second method, we used a denoising autoencoder (DAE) that learns mapping functions to distinguish between noise and signal (Zhu et al., 2019).In our tests, the threshold function performs well when the event is visible in the raw or spectral filtered data, but it fails when WT noise dominates and the event is hidden. In these cases, the DAE removes the WT noise from the data. However, the DAE must be trained with typical noise samples and high signal-to-noise ratio events to distinguish between signal and interfering noise. Using the threshold function and pre-noise can be applied immediately on real-time data and has a low computational cost. Using a noise model from our prerecorded database at the seismological station does not improve the result and it is more time consuming to find similar ground velocity conditions at the surrounding WTs.

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Internally Modulated Chirped Pulse Based Direct Detection Type φ-OTDR System with High Signal-to-Noise Ratio and Low Cost

Chinese Journal of Lasers ◽

10.3788/cjl201946.0806003 ◽

2019 ◽

Vol 46 (8) ◽

pp. 0806003

Author(s):

李鲁川 Luchuan Li ◽

卢斌 Bin Lu ◽

王校 Xiao Wang ◽

梁嘉靖 Jiajing Liang ◽

郑汉荣 Hanrong Zheng ◽

...

Keyword(s):

Direct Detection ◽

Signal To Noise Ratio ◽

Low Cost ◽

High Signal ◽

Signal To Noise ◽

Chirped Pulse ◽

Noise Ratio

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A Carbon-Based DNA Framework Nano–Bio Interface for Biosensing with High Sensitivity and a High Signal-to-Noise Ratio

ACS Sensors ◽

10.1021/acssensors.0c01745 ◽

2020 ◽

Vol 5 (12) ◽

pp. 3979-3987

Author(s):

Jing Su ◽

Wenhan Liu ◽

Shixing Chen ◽

Wangping Deng ◽

Yanzhi Dou ◽

...

Keyword(s):

Signal To Noise Ratio ◽

High Sensitivity ◽

High Signal ◽

Signal To Noise ◽

Noise Ratio ◽

Carbon Based

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A 77-GHz Six-Port Sensor for Accurate Near-Field Displacement and Doppler Measurements

Sensors ◽

10.3390/s18082565 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2565 ◽

Cited By ~ 3

Author(s):

Homa Arab ◽

Steven Dufour ◽

Emilia Moldovan ◽

Cevdet Akyel ◽

Serioja Tatu

Keyword(s):

Continuous Wave ◽

Signal To Noise Ratio ◽

Near Field ◽

Industrial Applications ◽

High Signal ◽

Millimetre Wave ◽

Sensing Applications ◽

Radar Sensing ◽

Cw Radar ◽

77 Ghz

A continuous-wave (CW) radar sensor design based on a millimetre-wave six-port interferometer is proposed. A complete sensor prototype is conceived of, fabricated and measured at 77 GHz for short-range professional and industrial applications. This sensor is designed to measure distances and Doppler frequencies with high accuracy, at a reasonable cost. Accurate phase measurements are also performed using the six-port technology, which makes it a promising candidate for CW radar sensing applications. Advances in the performance and functionality of six-port sensors are surveyed to highlight recent progress in this area. These include improvements in design, low power consumption, high signal to noise ratio, compactness, robustness and simplicity in realization. Given the fact that they are easy to fabricate, due to the lack of active circuits and being highly accurate, it is expected that six-port sensors will significantly contribute to the development of human tracking devices and industrial sensors in the near future. The entire circuit prototype, including the transmitter, the receiver antenna, the six-port interferometer and the four power detectors have been integrated on a die. The circuit is fabricated using a hybrid integrated technology on a 127-μm ceramic substrate with a relative permittivity of εr=9.8. Calibrated tuning forks are used to assess the performance of the six-port sensor experimentally for various frequencies.

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Double-Layer Flexible Neural Probe With Closely Spaced Electrodes for High-Density in vivo Brain Recordings

Frontiers in Neuroscience ◽

10.3389/fnins.2021.663174 ◽

2021 ◽

Vol 15 ◽

Author(s):

Sara Pimenta ◽

José A. Rodrigues ◽

Francisca Machado ◽

João F. Ribeiro ◽

Marino J. Maciel ◽

...

Keyword(s):

Double Layer ◽

Signal To Noise Ratio ◽

Low Cost ◽

High Signal ◽

Composition Analysis ◽

Assessment Tests ◽

Flexible Polymer ◽

Mouse Cortex ◽

Neural Probe

Flexible polymer neural probes are an attractive emerging approach for invasive brain recordings, given that they can minimize the risks of brain damage or glial scaring. However, densely packed electrode sites, which can facilitate neuronal data analysis, are not widely available in flexible probes. Here, we present a new flexible polyimide neural probe, based on standard and low-cost lithography processes, which has 32 closely spaced 10 μm diameter gold electrode sites at two different depths from the probe surface arranged in a matrix, with inter-site distances of only 5 μm. The double-layer design and fabrication approach implemented also provides additional stiffening just sufficient to prevent probe buckling during brain insertion. This approach avoids typical laborious augmentation strategies used to increase flexible probes’ mechanical rigidity while allowing a small brain insertion footprint. Chemical composition analysis and metrology of structural, mechanical, and electrical properties demonstrated the viability of this fabrication approach. Finally, in vivo functional assessment tests in the mouse cortex were performed as well as histological assessment of the insertion footprint, validating the biological applicability of this flexible neural probe for acquiring high quality neuronal recordings with high signal to noise ratio (SNR) and reduced acute trauma.

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A chemiluminescent protease probe for rapid, sensitive, and inexpensive detection of live Mycobacterium tuberculosis

10.1101/2020.09.14.296772 ◽

2020 ◽

Author(s):

Brett M. Babin ◽

Gabriela Fernandez-Cuervo ◽

Jessica Sheng ◽

Ori Green ◽

Alvaro A. Ordonez ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Signal To Noise Ratio ◽

Point Of Care ◽

High Sensitivity ◽

Drug Susceptibility ◽

Drug Susceptibility Testing ◽

High Signal ◽

Resource Limited ◽

Tb Diagnostics

AbstractTuberculosis (TB) is a top-ten cause of death worldwide. Successful treatment is often limited by insufficient diagnostic capabilities, especially at the point of care in low-resource settings. The ideal diagnostic must be fast, cheap, and require minimal clinical resources while providing high sensitivity, selectivity, and the ability to differentiate live from dead bacteria. We describe here the development of a Fast, Luminescent, and Affordable Sensor of Hip1 (FLASH) for the diagnosis and monitoring of drug sensitivity of Mycobacterium tuberculosis (Mtb). FLASH is a selective chemiluminescent substrate for the Mtb protease Hip1 that when processed, produces visible light that can be measured with a high signal to noise ratio using inexpensive sensors. FLASH is sensitive to fmol of recombinant Hip1 enzyme in vitro and can detect as few as thousands of Mtb cells in culture or in human sputum samples within minutes. The probe is highly selective for Mtb compared to other non-tuberculous mycobacteria and can distinguish live from dead cells. Importantly, FLASH can be used to measure antibiotic killing of Mtb in culture with greatly accelerated timelines compared to traditional protocols. Overall, FLASH has the potential to enhance both TB diagnostics and drug resistance monitoring in resource-limited settings.One Sentence SummaryA luminescent probe enables sensitive detection of Mycobacterium tuberculosis for diagnostics, treatment monitoring, and drug susceptibility testing.

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Electrode_configuration_DNA_Sensitivity_Biomicrofluidics

10.1149/osf.io/9pebk ◽

2019 ◽

Author(s):

Sagnik Basuray

Keyword(s):

High Frequency ◽

Signal To Noise Ratio ◽

Microfluidic Channel ◽

Convective Transport ◽

Electrical Impedance Spectroscopy ◽

Detection Sensitivity ◽

High Signal ◽

Diffusion Dynamics ◽

Interdigitated Microelectrode ◽

Carbon Based

Electrical impedance spectroscopy (EIS) sensors through rapid and cost-effectiveoften suffer from poor sensitivity. EIS sensors modified with carbon-basedtransducers show a higher conductance, thereby increasing the sensitivity of the sensor towards biomolecules like DNA. However, the EIS spectra are compromised by the parasitic capacitance of the electric double layer (EDL). Here, a new shear-enhanced, flow-through nonporous, non-planar interdigitated microelectrode sensor has been fabricated that shifts the EDL capacitor to high frequencies. Enhanced convective transport in this sensor disrupts the diffusion dynamics of the EDL, shifting its EIS spectra to high frequency. Concomitantly, the DNA detection signal shifts to high frequency, making the sensor very sensitive, rapid with a high signal to noise ratio. The device consists of a microfluidic channel sandwiched between two sets of top and bottom interdigitated microelectrodes. One of the sets of microelectrodes is packed with carbon-based transducer material like carboxylated single-walled carbon nanotube (SWCNT). Multiple parametric studies of three different electrode configurations of the sensor along with different carbon-based transducer materials are undertaken to understand the fundamental physics and electrochemistry. Sensors packed with SWCNT show femtomolar detection sensitivity from all the different electrode configurations, for a short target-DNA. A 20-fold jump in the signal is noticed from the unique working electrode configuration in contrast to the other electrode configurations. This demonstrates the potential of the sensor for a significant increase in the sensitivity of the detection of DNA and other biomolecules.

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