High responsivity YBa2Cu3O7−xmicrobolometers with fast response times

1993 ◽  
Vol 73 (3) ◽  
pp. 1531-1533 ◽  
Author(s):  
Kin Li ◽  
Joseph E. Johnson ◽  
Bruce W. Aker
Keyword(s):  
Response Times ◽  
Fast Response ◽  
High Responsivity

Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

1990 ◽  
Vol 48 (4) ◽  
pp. 728-729
Author(s):  
M.J. Kim ◽  
L.C. Liu ◽  
S.H. Risbud ◽  
R.W. Carpenter
Keyword(s):  
Quantum Dots ◽  
Borosilicate Glass ◽  
Glass Matrix ◽  
Optical Switching ◽  
Response Times ◽  
Fast Response ◽  
Processing Technique ◽  
Internal Stresses ◽  
Electron Hole ◽  
Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

Compact and efficient gas diffusion electrodes based on nanoporous alumina membranes for microfuel cells and gas sensors

The Analyst ◽  
2020 ◽  
Vol 145 (1) ◽  
pp. 122-131 ◽  
Author(s):  
Wanda V. Fernandez ◽  
Rocío T. Tosello ◽  
José L. Fernández
Keyword(s):  
Response Times ◽  
Hydrogen Oxidation ◽  
Fast Response ◽  
Gas Diffusion ◽  
Limiting Current ◽  
Gas Diffusion Electrodes ◽  
Nanoporous Alumina ◽  
Alumina Membranes ◽  
Current Densities ◽  
Microfuel Cells

Gas diffusion electrodes based on nanoporous alumina membranes electrocatalyze hydrogen oxidation at high diffusion-limiting current densities with fast response times.

scholarly journals FEM Simulation of Frequency-Selective Surface Based on Thermoelectric Bi-Sb Thin Films for THz Detection

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 119
Author(s):  
Anastasiia Tukmakova ◽  
Ivan Tkhorzhevskiy ◽  
Artyom Sedinin ◽  
Aleksei Asach ◽  
Anna Novotelnova ◽  
...  
Keyword(s):  
Thin Films ◽  
Response Times ◽  
Fem Simulation ◽  
Film Surface ◽  
Frequency Selective Surface ◽  
Fast Response ◽  
Radiation Absorption ◽  
Thz Radiation ◽  
Frequency Filter ◽  
Frequency Selective

Terahertz (THz) filters and detectors can find a wide application in such fields as: sensing, imaging, security systems, medicine, wireless connection, and detection of substances. Thermoelectric materials are promising basis for THz detectors’ development due to their sensitivity to the THz radiation, possibility to be heated under the THz radiation and produce voltage due to Seebeck effect. Thermoelectric thin films of Bi-Sb solid solutions are semimetals/semiconductors with the band gap comparable with THz energy and with high thermoelectric conversion efficiency at room temperature. Detecting film surface can be transformed into a periodic frequency selective surface (FSS) that can operate as a frequency filter and increases the absorption of THz radiation. We report for the first time about the simulation of THz detector based on thermoelectric Bi-Sb thin-filmed frequency-selective surface. We show that such structure can be both detector and frequency filter. Moreover, it was shown that FSS design increases not only a heating due to absorption but a temperature gradient in Bi-Sb film by two orders of magnitude in comparison with continuous films. Local temperature gradients can reach the values of the order of 100 K·mm−1. That opens new perspectives for thin-filmed thermoelectric detectors’ efficiency increase. Temperature difference formed due to THz radiation absorption can reach values on the order of 1 degree. Frequency-transient calculations show the power dependence of film temperature on time with characteristic saturation at times around several ms. That points to the perspective of reaching fast response times on such structures.

Novel optical oxygen sensing by phosphorescence quenching of palladium porphyrin self-assembled film on alumina plate

2000 ◽  
Vol 04 (02) ◽  
pp. 179-184 ◽  
Author(s):  
YUTAKA AMAO ◽  
KEISUKE ASAI ◽  
ICHIRO OKURA
Keyword(s):  
Oxygen Pressure ◽  
Oxygen Sensor ◽  
Response Times ◽  
Oxygen Sensing ◽  
Fast Response ◽  
Phosphorescence Quenching ◽  
Highly Sensitive ◽  
Optical Oxygen Sensor ◽  
Self Assembled ◽  
Quenching By Oxygen

An optical oxygen sensor based on the phosphorescence quenching of palladium tetrakis(4-carboxyphenyl)porphyrin (PdTCPP) self-assembled film (SAM) on alumina plate was developed. The phosphorescence intensity of PdTCPP film decreased with increasing oxygen pressure, indicating that the film can be used as an optical oxygen-sensing device based on phosphorescence quenching by oxygen. The ratio I0/I100 as a sensitivity measure of the sensing film is estimated to be 17.7, showing that the film is a highly sensitive device for oxygen pressure. The film obeyed Stern–Volmer plots with a multisite model and possessed good operational stability and a fast response. Response times are 36 s for deoxygenated to oxygenated conditions and 148 s for the reverse conditions.

scholarly journals Solar-blind ultraviolet photodetector based on graphene/vertical Ga2O3 nanowire array heterojunction

Nanophotonics ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 1557-1562 ◽  
Author(s):  
Tao He ◽  
Yukun Zhao ◽  
Xiaodong Zhang ◽  
Wenkui Lin ◽  
Kai Fu ◽  
...  
Keyword(s):  
Response Times ◽  
Nanowire Array ◽  
Graphene Film ◽  
Fast Response ◽  
Nanowire Arrays ◽  
Monolayer Graphene ◽  
Ultraviolet Photodetector ◽  
Solar Blind ◽  
Decay Times ◽  
First Time

AbstractIn this paper, a solar-blind ultraviolet photodetector (PD) based on the graphene/vertical Ga2O3 nanowire array heterojunction was proposed and demonstrated. To the best of our knowledge, it is the first time that vertical Ga2O3 nanowire arrays have been realized. Ga2O3 nanowires were obtained by thermally oxidizing GaN nanowires grown by molecular beam epitaxy on n-doped Si substrate. Then, a monolayer graphene film was transferred to Ga2O3 nanowires to form the graphene/vertical Ga2O3 nanowire array heterojunction and transparent electrodes. The fabricated device exhibited a responsivity (R) of 0.185 A/W and rejection ratio (R258 nm/R365 nm) of 3×104 at the bias of −5 V. Moreover, the fast response times of this PD were 9 and 8 ms for the rise and decay times under 254 nm illumination, respectively, which are attributed to the unique properties of nanowire arrays and the graphene/vertical Ga2O3 nanowire array heterojunction structure.

A new device for highly accurate gas flow control with extremely fast response times

2011 ◽  
Author(s):  
Kevin Boyd ◽  
Adam Monkowski ◽  
Jialing Chen ◽  
Tao Ding ◽  
Ray Malone ◽  
...  
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Response Times ◽  
Fast Response ◽  
New Device

Dynamics of Thin Film NiTi Cantilevers on Si

1993 ◽  
Vol 311 ◽  
Author(s):  
A.Peter Jardine ◽  
Peter G. Mercado
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Response Times ◽  
Bulk Material ◽  
Fast Response ◽  
Free Standing ◽  
Promising Candidate ◽  
Strain Measurements ◽  
Micro Actuators ◽  
Cycling Time

ABSTRACTAlthough the thermo-mechanical properties of NiTi are well known for bulk material, its deposition and utilization as a thin film are still in their earliest stages of research. The deposition of thin-films of Shape Memory Effect NiTi onto Si(100) wafers offers several advantages over bulk NiTi, including fast response times and comparatively large transformation forces. This has made it a promising candidate material as micro-actuators for Micro-Electro-Mechanical (MEMS) systems as well as for strain measurements. The cycling time for actuation was measured for a 20 μm free standing NiTi thin film cantilever. It was demonstrated that cycling frequencies of up to 50 Hz are achievable.

scholarly journals Numerical Fatigue Analysis of a Prototype Francis Turbine Runner in Low-Load Operation

2019 ◽  
Vol 4 (3) ◽  
pp. 21 ◽  
Author(s):  
Julian Unterluggauer ◽  
Eduard Doujak ◽  
Christian Bauer
Keyword(s):  
Fatigue Damage ◽  
Power Plants ◽  
Response Times ◽  
Fluid Dynamic ◽  
Numerical Approach ◽  
Fast Response ◽  
Francis Turbine ◽  
Hydro Power ◽  
Hydraulic Machines ◽  
Low Load

Depending on a dynamical energy market dominated by the influence of volatile energies, the operators of hydro-power plants are forced to extend the operating range of their hydraulic machines to stay competitive. High flexibility towards low-load, a rising number of start-ups and fast response times are required for better control of the electrical grid. The major downside of these operating regions is that pressure pulsations, which are induced by the means of flow phenomena, lead to higher fatigue damage regarding the runner. Therefore, site measurements in combination with numerical methods can be used to gain a deeper understanding of the runner lifetime. This paper presents a numerical approach to understand the critical operation zones and access fatigue damage, including steady state, unsteady and transient computational fluid dynamic (CFD) one-way coupled with a transient finite element method (FEM).

scholarly journals Intensity Modulated Photothermal Measurements of NO2 with a Compact Fiber-Coupled Fabry–Pérot Interferometer

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3341 ◽  
Author(s):  
Philipp Breitegger ◽  
Benjamin Lang ◽  
Alexander Bergmann
Keyword(s):  
Nitrogen Dioxide ◽  
Health Effects ◽  
Response Times ◽  
Fast Response ◽  
Reliable Measurement ◽  
Mechanical Vibrations ◽  
Temperature Changes ◽  
Adverse Health Effects ◽  
Intensity Modulated ◽  
Fabry Perot

Sensors for the reliable measurement of nitrogen dioxide concentrations are of high interest due the adverse health effects of this pollutant. This work employs photothermal spectroscopy to measure nitrogen dioxide concentrations at the parts per billion level. Absorption induced temperature changes are detected by means of a fiber-coupled Fabry–Pérot interferometer. The small size of the interferometer enables small detection volumes, paving the way for miniaturized sensing concepts as well as fast response times, demonstrated down to 3 s. A normalized noise equivalent absorption of 7.5 × 10 − 8 cm−1W/ Hz is achieved. Additionally, due to the rigid structure of the interferometer, the sensitivity to mechanical vibrations is shown to be minor.

Development of a Fast Solar Tracker Enabling Atmospheric Direct Sun Remote Sensing Applications on Different Moving Platforms

2020 ◽  
Author(s):  
Ralph Kleinschek ◽  
Julian Kostinek ◽  
Philip Holzbeck ◽  
Marvin Knapp ◽  
Andreas Luther ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Precision ◽  
Response Times ◽  
Tracking System ◽  
Fast Response ◽  
Lessons Learned ◽  
The Sun ◽  
Mobile Platforms ◽  
Sensing Applications ◽  
Ozone Depleting Substances

<p>Spectroscopic direct sun remote sensing of the atmosphere offers an essential tool for the validation of models and satellite observations as well as for the monitoring of emissions. Validation missions for greenhouse gas monitoring satellites are essential to improve the performances of the satellite products, thereby gaining a better understanding of the dynamics between sources and sinks. Furthermore, the monitoring of ozone-depleting substances is a vital contribution to observe the progress in restoring the ozone layer. A high tracking precision is in particular for measuring CO<sub>2</sub> and CH<sub>4</sub> columns required. We aim for an accuracy better than 0.05°.</p><p>This work presents the development of a compact and reliable stand-alone sun tracker for mobile applications. The tracking is camera-based and has two modes. In the first mode, image processing using the image of a fish-eye lens with a field of view of 185° monitoring the entire hemisphere above the instrument calculates the coarse position of the sun. On reaching this coarse position, the other camera-based tracking system takes over and centers the projection of the sun with high precision and fast response times (100 Hz control loop). The tracker is compatible with different kinds of spectrometers like grating spectrometers and Fourier transform infrared spectrometers (FTIR). The tracking is also suitable for different mobile platforms like cars, ships, or stratospheric balloons. </p><p>During the CoMet (Carbon Dioxide and Methane Misson 2018) campaign, the tracking has performed well in a stop and go manner on a car-mounted setup. On every stop, the tracker was able to autonomously find the sun regardless of the relative position of the vehicle. For the MORE-2 (Measuring Ocean REferences 2) campaign onboard a research vessel over the Pacific ocean, the tracking allowed for using over 99 % of the measuring time for high-precision retrievals of CO<sub>2</sub> and CH<sub>4</sub> using an EM27/SUN FTIR. Based on the lessons learned during the performed campaigns, a further improved version of the tracker for flying on a stratospheric balloon in August 2020 is in development. </p>

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