Schottky-Contacted WSe2 Hot-Electron Photodetectors with Fast Response and High Sensitivity

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

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A Full-Range Flexible and Printed Humidity Sensor Based on a Solution-Processed P(VDF-TrFE)/Graphene-Flower Composite

Nanomaterials ◽

10.3390/nano11081915 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1915

Author(s):

Shenawar Ali Khan ◽

Muhammad Saqib ◽

Muhammad Muqeet Rehman ◽

Hafiz Mohammad Mutee Ur Rehman ◽

Sheik Abdur Rahman ◽

...

Keyword(s):

Active Layer ◽

Humidity Sensor ◽

High Reliability ◽

Full Range ◽

High Sensitivity ◽

Fast Response ◽

Considerable Change ◽

Relative Humidity Range ◽

Response And Recovery ◽

Proportional Relationship

A novel composite based on a polymer (P(VDF-TrFE)) and a two-dimensional material (graphene flower) was proposed as the active layer of an interdigitated electrode (IDEs) based humidity sensor. Silver (Ag) IDEs were screen printed on a flexible polyethylene terephthalate (PET) substrate followed by spin coating the active layer of P(VDF-TrFE)/graphene flower on its surface. It was observed that this sensor responds to a wide relative humidity range (RH%) of 8–98% with a fast response and recovery time of 0.8 s and 2.5 s for the capacitance, respectively. The fabricated sensor displayed an inversely proportional response between capacitance and RH%, while a directly proportional relationship was observed between its impedance and RH%. P(VDF-TrFE)/graphene flower-based flexible humidity sensor exhibited high sensitivity with an average change of capacitance as 0.0558 pF/RH%. Stability of obtained results was monitored for two weeks without any considerable change in the original values, signifying its high reliability. Various chemical, morphological, and electrical characterizations were performed to comprehensively study the humidity-sensing behavior of this advanced composite. The fabricated sensor was successfully used for the applications of health monitoring and measuring the water content in the environment.

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Alcohol-based highly conductive polymer for conformal nanocoatings on hydrophobic surfaces toward a highly sensitive and stable pressure sensor

NPG Asia Materials ◽

10.1038/s41427-020-00238-z ◽

2020 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Jung Joon Lee ◽

Srinivas Gandla ◽

Byeongjae Lim ◽

Sunju Kang ◽

Sunyoung Kim ◽

...

Keyword(s):

Pressure Sensor ◽

Mechanical Stability ◽

Exchange Process ◽

Conductive Polymer ◽

High Sensitivity ◽

Fast Response ◽

Pdms Surface ◽

Practical Applications ◽

Sensor Applications ◽

Water Based

Abstract Conformal and ultrathin coating of highly conductive PEDOT:PSS on hydrophobic uneven surfaces is essential for resistive-based pressure sensor applications. For this purpose, a water-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution was successfully exchanged to an organic solvent-based PEDOT:PSS solution without any aggregation or reduction in conductivity using the ultrafiltration method. Among various solvents, the ethanol (EtOH) solvent-exchanged PEDOT:PSS solution exhibited a contact angle of 34.67°, which is much lower than the value of 96.94° for the water-based PEDOT:PSS solution. The optimized EtOH-based PEDOT:PSS solution exhibited conformal and uniform coating, with ultrathin nanocoated films obtained on a hydrophobic pyramid polydimethylsiloxane (PDMS) surface. The fabricated pressure sensor showed high performances, such as high sensitivity (−21 kPa−1 in the low pressure regime up to 100 Pa), mechanical stability (over 10,000 cycles without any failure or cracks) and a fast response time (90 ms). Finally, the proposed pressure sensor was successfully demonstrated as a human blood pulse rate sensor and a spatial pressure sensor array for practical applications. The solvent exchange process using ultrafiltration for these applications can be utilized as a universal technique for improving the coating property (wettability) of conducting polymers as well as various other materials.

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A Self-Powered Nanogenerator for the Electrical Protection of Integrated Circuits from Trace Amounts of Liquid

Nano-Micro Letters ◽

10.1007/s40820-019-0338-1 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 3

Author(s):

Zhuang Hui ◽

Ming Xiao ◽

Daozhi Shen ◽

Jiayun Feng ◽

Peng Peng ◽

...

Keyword(s):

Integrated Circuits ◽

High Performance ◽

Printed Circuit Board ◽

Short Circuit ◽

High Sensitivity ◽

Short Circuit Current ◽

Fast Response ◽

Open Circuit ◽

Circuit Board ◽

Self Powered

Abstract With the increase in the use of electronic devices in many different environments, a need has arisen for an easily implemented method for the rapid, sensitive detection of liquids in the vicinity of electronic components. In this work, a high-performance power generator that combines carbon nanoparticles and TiO2 nanowires has been fabricated by sequential electrophoretic deposition (EPD). The open-circuit voltage and short-circuit current of a single generator are found to exceed 0.7 V and 100 μA when 6 μL of water was applied. The generator is also found to have a stable and reproducible response to other liquids. An output voltage of 0.3 V was obtained after 244, 876, 931, and 184 μs, on exposure of the generator to 6 μL of water, ethanol, acetone, and methanol, respectively. The fast response time and high sensitivity to liquids show that the device has great potential for the detection of small quantities of liquid. In addition, the simple easily implemented sequential EPD method ensures the high mechanical strength of the device. This compact, reliable device provides a new method for the sensitive, rapid detection of extraneous liquids before they can impact the performance of electronic circuits, particularly those on printed circuit board.

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Combustion Synthesis of La0.65Sr0.35MnO3 and its Sensing Properties for NO2

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.680.208 ◽

2016 ◽

Vol 680 ◽

pp. 208-211

Author(s):

Lian Lian Wu ◽

Qiang Li ◽

Dan Yu Jiang ◽

Jin Feng Xia

Keyword(s):

Solid Phase ◽

High Sensitivity ◽

Combustion Method ◽

Fast Response ◽

Size Analysis ◽

Phase Method ◽

X Ray Diffraction ◽

Ultrafine Structure ◽

Nox Sensor ◽

Solid Phase Method

In this paper, La0.65Sr0.35MnO3 (LSM) oxide powder with ultrafine structure has been synthesized by self-propagating combustion method. The powders were characterized by X-ray diffraction, scanning electron microscopy and laser size analysis. Compared to the powders prepared by traditional solid-phase method, the grain size of powders prepared by self-propagating combustion method is relatively small and uniform. Starting from ultrafine LSM powders, sensing electrode (SE) for NO2 mixed-potential sensors based on yttria-stablized zirconia (YSZ) was fabricated. As-obtained NO2 sensor displays fast response and high sensitivity (25.4mV/decade). The response values of the sensor have good linear relationship with the logarithm of NO2 concentration varying from 30ppm to 500ppm.Keywords:Self-propagating combustion method; La0.65Sr0.35MnO3; NOx sensor; YSZ

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pH-Insensitive FRET Voltage Dyes

CrossRef Listing of Deleted DOIs ◽

10.1177/1087057107302113 ◽

2007 ◽

Vol 12 (5) ◽

pp. 656-667 ◽

Cited By ~ 18

Author(s):

Michael P. Maher ◽

Nyan-Tsz Wu ◽

Hong Ao

Keyword(s):

Ion Channel ◽

High Throughput ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

High Sensitivity ◽

Fast Response ◽

Resting Membrane Potential ◽

Absolute Calibration ◽

High Throughput Assay ◽

Voltage Sensitive Dyes

Many high-throughput ion channel assays require the use of voltage-sensitive dyes to detect channel activity in the presence of test compounds. Dye systems employing Förster resonance energy transfer (FRET) between 2 membrane-bound dyes are advantageous in combining high sensitivity, relatively fast response, and ratiometric output. The most widely used FRET voltage dye system employs a coumarin fluorescence donor whose excitation spectrum is pH dependent. The authors have validated a new class of voltage-sensitive FRET donors based on a pyrene moiety. These dyes are significantly brighter than CC2-DMPE and are not pH sensitive in the physiological range. With the new dye system, the authors demonstrate a new high-throughput assay for the acid-sensing ion channel (ASIC) family. They also introduce a novel method for absolute calibration of voltage-sensitive dyes, simultaneously determining the resting membrane potential of a cell. ( Journal of Biomolecular Screening 2007:656-667)

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Effect of Operating Temperature on Characteristics of Single-Walled Carbon Nanotubes Gas Sensor

Materials Science Forum ◽

10.4028/www.scientific.net/msf.486-487.485 ◽

2005 ◽

Vol 486-487 ◽

pp. 485-488 ◽

Cited By ~ 1

Author(s):

Hong Quang Nguyen ◽

Mai Van Trinh ◽

Jeung Soo Huh

Keyword(s):

Carbon Nanotubes ◽

Gas Sensor ◽

Gas Adsorption ◽

Operating Temperature ◽

High Sensitivity ◽

Single Walled Carbon Nanotubes ◽

Fast Response ◽

Carrier Gas ◽

Single Walled Carbon ◽

Walled Carbon Nanotubes

The effect of operating temperature on characteristics of single-walled carbon nanotubes (SWNT) based gas sensor was investigated. SWNT-based sensor was fabricated from SWNT powder (Iljin Nanotech, Korea) by screen-printing method. SWNT powder (30 mg, AP grade) was dispersed into 0.78 gram a-terpineol (Aldrich) by ultrasonic vibration for 1 hour then stirred manually for 1 hour to increase adhesion. From this condensed solution, a thick film of SWNT was printed onto alumina substrates. The film then was sintered at 300oC for 2 hours to remove residual impurities. Upon exposure to some gases such as nitrogen, ammonia or nitric oxide, resistance of the sensor dramatically changes due to gas adsorption. In our experiments, SWNT-based sensor was employed to detect NH3 gas in N2 ambience. After saturated of N2, the sensor exposes to NH3 with various concentrations (from 5 ppm to 100 ppm, diluted by N2 as carrier gas). This sensor exhibits a fast response, high sensitivity but slow recovery at room temperature. By heating at high temperature and increasing the flow-rate of carrier gas, NH3 gas desorbs easily and recovery of the sensor improved. The heating also influenced the characteristics of sensors such as response and reproducibility. Other special changes in electric property of SWNT-based sensor caused by heating are also discussed.

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Two-dimensional SnS2 materials as high-performance NO2 sensors with fast response and high sensitivity

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2017.08.091 ◽

2018 ◽

Vol 255 ◽

pp. 616-621 ◽

Cited By ~ 34

Author(s):

Young-Ho Kim ◽

Duy-Thach Phan ◽

Seungbae Ahn ◽

Ki-Hun Nam ◽

Cheol-Min Park ◽

...

Keyword(s):

High Performance ◽

High Sensitivity ◽

Fast Response ◽

Two Dimensional

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Assay of Phospholipase D Activity by an Amperometric Choline Oxidase Biosensor

Sensors ◽

10.3390/s20051304 ◽

2020 ◽

Vol 20 (5) ◽

pp. 1304 ◽

Cited By ~ 1

Author(s):

Rosanna Ciriello ◽

Antonio Guerrieri

Keyword(s):

Phospholipase D ◽

Limit Of Detection ◽

High Sensitivity ◽

Fast Response ◽

Borate Buffer ◽

Choline Oxidase ◽

Linear Calibration ◽

Real Sample Analysis ◽

Polypyrrole Film ◽

Overoxidized Polypyrrole

A novel electrochemical method to assay phospholipase D (PLD) activity is proposed based on the employment of a choline biosensor realized by immobilizing choline oxidase through co-crosslinking on an overoxidized polypyrrole film previously deposited on a platinum electrode. To perform the assay, an aliquot of a PLD standard solution is typically added to borate buffer containing phosphatidylcholine at a certain concentration and the oxidation current of hydrogen peroxide is then measured at the rotating modified electrode by applying a detection potential of +0.7 V vs. SCE. Various experimental parameters influencing the assay were studied and optimized. The employment of 0.75% (v/v) Triton X-100, 0.2 mM calcium chloride, 5 mM phosphatidylcholine, and borate buffer at pH 8.0, ionic strength (I) 0.05 M allowed to achieve considerable current responses. In order to assure a controlled mass transport and, at the same time, high sensitivity, an electrode rotation rate of 200 rpm was selected. The proposed method showed a sensitivity of 24 (nA/s)⋅(IU/mL)−1, a wide linear range up to 0.33 IU/mL, fast response time and appreciable long-term stability. The limit of detection, evaluated from the linear calibration curve, was 0.005 IU/mL (S/N = 3). Finally, due to the presence of overoxidized polypyrrole film characterized by notable rejection properties towards electroactive compounds, a practical application to real sample analysis can be envisaged.

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