Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

scholarly journals Computational Method for Simulating Thermoset Polymer Curing and Prediction of Thermophysical Properties

2020 ◽  
Author(s):  
Jeffrey Sanders ◽  
Carla E. Estridge ◽  
Matthew B Jackson ◽  
Thomas JL Mustard ◽  
Samuel J. Tucker ◽  
...  
Keyword(s):  
High Throughput ◽  
Thermophysical Properties ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Polymer Network ◽  
Thermomechanical Properties ◽  
Computational Method ◽  
Cross Linking ◽  
Automated Simulation

Thermoset polymers are an area of intense research due to their low cost, ease of processing, environmental resistance, and unique physical properties. The favorable properties of this class of polymers have many applications in aerospace, automotive, marine, and sports equipment industries. Molecular simulations of thermosets are frequently used to model formation of the polymer network, and to predict the thermomechanical properties. These simulations usually require custom algorithms that are not easily accessible to non-experts and not suited for high throughput screening. To address these issues, we have developed a robust cross-linking algorithm that can incorporate different types of chemistries and leverage GPU-enabled molecular dynamics simulations. Automated simulation analysis tools for cross-linking simulations are also presented. Using four well known epoxy/amine formulations as a foundational case study and benzoxazine as an example of how additional chemistries can be modeled, we demonstrate the power of the algorithm to accurately predict curing and thermophysical properties. These tools are able to streamline the thermoset simulation process, opening up avenues to in-silico high throughput screening for advanced material development.

scholarly journals On-Body Characterization of Planar Differential Antennas for Multiple, Wide, and Narrow Bands

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Luigi Vallozzi ◽  
Domenico Pepe ◽  
Thijs Castel ◽  
Hendrik Rogier ◽  
Domenico Zito
Keyword(s):  
Human Body ◽  
Ad Hoc ◽  
Low Cost ◽  
Experimental Tests ◽  
Body Measurements ◽  
Antenna Performance ◽  
Sensing Applications ◽  
The Impact ◽  
Narrow Bands

This paper reports the results of the on-body experimental tests of a set of four planar differential antennas, originated by design variations of radiating elements with the same shape and characterized by the potential for covering wide and narrow bands. All the antenna designs have been implemented on low-cost FR4 substrate and characterized experimentally through on-body measurements. The results show the impact of the proximity to the human body on antenna performance and the opportunities in terms of potential coverage of wide and narrow bands for future ad hoc designs and implementations through wearable substrates targeting on-body and off-body communication and sensing applications.

Low cost sponge based piezocapacitive sensors using a single step leavening agent mediated autolysis process

2018 ◽  
Vol 6 (20) ◽  
pp. 5473-5481 ◽  
Author(s):  
Chithra Parameswaran ◽  
Dipti Gupta
Keyword(s):  
Real Time ◽  
Low Cost ◽  
Single Step ◽  
Large Area ◽  
Sensing Applications ◽  
Autolysis Process

A single step, low cost, large area and shape scalable method of obtaining elastomer sponge is achieved through leavening agent autolysis with exceptional sensitivity tunability for real time sensing applications.

scholarly journals Slotted ALOHA on LoRaWAN-Design, Analysis, and Deployment

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 838 ◽  
Author(s):  
Tommaso Polonelli ◽  
Davide Brunelli ◽  
Achille Marzocchi ◽  
Luca Benini
Keyword(s):  
Single Channel ◽  
Low Cost ◽  
Network Throughput ◽  
Sensor Nodes ◽  
Slotted Aloha ◽  
Medium Access ◽  
Packet Collision ◽  
Sensing Applications ◽  
Hardware Platforms ◽  
The Impact

LoRaWAN is one of the most promising standards for long-range sensing applications. However, the high number of end devices expected in at-scale deployment, combined with the absence of an effective synchronization scheme, challenge the scalability of this standard. In this paper, we present an approach to increase network throughput through a Slotted-ALOHA overlay on LoRaWAN networks. To increase the single channel capacity, we propose to regulate the communication of LoRaWAN networks using a Slotted-ALOHA variant on the top of the Pure-ALOHA approach used by the standard; thus, no modification in pre-existing libraries is necessary. Our method is based on an innovative synchronization service that is suitable for low-cost wireless sensor nodes. We modelled the LoRaWAN channel with extensive measurement on hardware platforms, and we quantified the impact of tuning parameters on physical and medium access control layers, as well as the packet collision rate. Results show that Slotted-ALOHA supported by our synchronization service significantly improves the performance of traditional LoRaWAN networks regarding packet loss rate and network throughput.

scholarly journals Theoretical Uniformity Analysis and Improvement of Spray Deposition by Mixing Nozzles with Heating Conditions

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 81
Author(s):  
Xuran Dong ◽  
Xiaolong Pan ◽  
Xianxian Gao ◽  
Haisheng Fang
Keyword(s):  
High Speed ◽  
Heating Temperature ◽  
Spray Deposition ◽  
Low Cost ◽  
Spray Coating ◽  
Deposition Process ◽  
Test Method ◽  
Large Area ◽  
Orthogonal Test Method ◽  
Experimental Trials

Spray coating is widely used in the manufacture of deposited layers of electronic devices due to its unique advantages of high-speed deposition over a large area. To improve the spray deposition process for further low-cost and uniform production, the uniformity of the spray deposition should be systematically investigated. The current study, however, mainly focuses on the experimental trials with few numerical directions especially for the mixing nozzle sprayers with heating conditions. In the paper, we conduct a theoretical study on the uniformity of the internal and external mixing nozzles. The influencing factors include the initial angle, the total ink flow rate, the transporting gas velocity and the distance from the nozzle to the substrate. Then, the orthogonal test method is adopted to obtain the optimal combination of the parameters. Finally, the effects of different heating modes on the uniformity have been further studied. The results show that these factors influence the uniformity with the two types of nozzles to a different degree. The evaporation of the atomized droplets can effectively improve the uniformity in a certain temperature range. The heating temperature with the highest uniformity is various depending on the heating modes, which should be carefully addressed during the actual production.

scholarly journals Low-Cost, Disposable, Flexible and Highly Reproducible Screen Printed SERS Substrates for the Detection of Various Chemicals

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Wei Wu ◽  
Li Liu ◽  
Zhigao Dai ◽  
Juhua Liu ◽  
Shuanglei Yang ◽  
...  
Keyword(s):  
Screen Printing ◽  
Large Scale ◽  
Low Cost ◽  
Large Area ◽  
Sers Substrates ◽  
Sensing Applications ◽  
Relative Standard ◽  
Sers Detection ◽  
On Line ◽  
Liquid Milk

Abstract Ideal SERS substrates for sensing applications should exhibit strong signal enhancement, generate a reproducible and uniform response and should be able to fabricate in large-scale and low-cost. Herein, we demonstrate low-cost, highly sensitive, disposable and reproducible SERS substrates by means of screen printing Ag nanoparticles (NPs) on a plastic PET (Polyethylene terephthalate) substrates. While there are many complex methods for the fabrication of SERS substrates, screen printing is suitable for large-area fabrication and overcomes the uneven radial distribution. Using as-printed Ag substrates as the SERS platform, detection of various commonly known chemicals have been done. The SERS detection limit of Rhodamine 6G (R6G) is higher than the concentration of 1 × 10−10 M. The relative standard deviation (RSD) value for 784 points on the detection of R6G and Malachite green (MG) is less than 20% revealing a homogeneous SERS distribution and high reproducibility. Moreover, melamine (MA) is detected in fresh liquid-milk without additional pretreatment, which may accelerate the application of rapid on-line detection of MA in liquid milk. Our screen printing method highlights the use of large-scale printing strategies for the fabrication of well-defined functional nanostructures with applications well beyond the field of SERS sensing.

scholarly journals Plasmonic nanoparticle enhanced and extended performance of Light-sensitive nanocrystal skins

2013 ◽  
Vol 1509 ◽  
Author(s):  
Shahab Akhavan ◽  
Kivanc Gungor ◽  
Hilmi Volkan Demir
Keyword(s):  
Optical Absorption ◽  
Low Cost ◽  
Great Promise ◽  
Silver Nanostructures ◽  
Ambient Conditions ◽  
Large Area ◽  
Plasmonic Nanoparticle ◽  
Noise Current ◽  
External Bias ◽  
Sensing Applications

ABSTRACTWe report on light-sensitive nanocrystal skin (LS-NS) platforms composed of monolayer visible nanocrystals (NCs) on top of bilayers of polyelectrolyte polymers. These LS-NS devices are operated on the principle of photogenerated potential buildup, unlike common photodetectors that operate on the basis of charge collection. The resulting devices are as highly sensitive as common photosensors, despite utilizing a monolayer of NCs and requiring no applied external bias. In this device architecture, using only a single NC monolayer also allows to reduce noise current generation. This LS-NS platform is highly stable under ambient conditions with fully sealed NC monolayer, promising for low-cost large-area UV/visible sensing applications. However, such visible NC based LS-NS devices exhibit limited performance in the long wavelength range due to the low optical absorption of these NCs (e.g., CdTe NCs) in this spectral range. Here, to enhance the device sensitivity, incorporating silver nanoparticles into LS-NS is proposed and demonstrated. For that, the optical absorption of CdTe monolayer NCs in the LS-NS devices is increased using the embedded silver nanostructures. With plasmon coupling, we observe a 2.6-fold enhancement factor in the photosensitivity around the localized surface plasmonic resonance peak of the nanostructures. Higher sensitivity improvement is also obtained at longer wavelengths. To predict the enhancement in the sensitivity of the LS-NS, numerical simulations are performed and the simulation results are found to agree well with the experimental data. Plasmonically enhanced LS-NS hold great promise for large-area photosensing applications extending from UV to IR including windows and facades of smart buildings.

Power Feeding in Large Area PECVD of Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
J. Kuske ◽  
U. Stephan ◽  
O. Steinke ◽  
S. Röhlecke
Keyword(s):  
Amorphous Silicon ◽  
Silicon Layer ◽  
Deposition Process ◽  
Small Scale ◽  
Voltage Distribution ◽  
Large Area ◽  
Electrode Area ◽  
Electrical Devices ◽  
Device Applications ◽  
Design Power

ABSTRACTPlasma processes are usually worked out in a small-scale environment (electrode area maximum 121 cm2, rf- and VHF- excitation frequencies). In order to meet the requirements of large area device applications they have to be upscaled. The investigations of glow discharge systems for different PECVD reactors (parallel plate- and coaxial electrodes) have shown, that the reactor design (power supply, line connection) sharply influences the large area deposition process. The voltage distribution on the driven electrode especially determines the uniformity of the deposited layer thickness. Possibilities which influence the voltage distribution on large areas will be discussed. The results of large area electrode description as an electrical line will be discussed in comparison with different reactor configurations and the optimization of the behavior of the deposition process. The experimental results of a coaxial reactor (electrode area 5000 cm2, substrate length 120 cm) show that a homogenous deposition of amorphous silicon (layer uniformity of thickness over the length better ± 7 %) by connecting the driven electrode with additional electrical devices is possible.

scholarly journals Utilization of Amorphous Silicon Carbide (a-Si:C:H) as a Resistive Layer in Gas Microstrip Detectors

1995 ◽  
Vol 377 ◽  
Author(s):  
W. S. Hong ◽  
H. S. Cho ◽  
V. Perez-Mendez ◽  
W. G. Gong
Keyword(s):  
Amorphous Silicon ◽  
Low Cost ◽  
Chemical Vapor ◽  
Light Sensitivity ◽  
Attractive Alternative ◽  
Large Area ◽  
Doping Density ◽  
Resistive Layer ◽  
Wide Range ◽  
Microstrip Detectors

ABSTRACTThin semiconducting films of hydrogenated amorphous silicon (a-Si:H) and its carbon alloy (a-Si:C:H) were applied to gas microstrip detectors in order to control gain instabilities due to charges on the substrate. Thin (∼100 nm) layers of a-Si:H or p-doped a-Si:C:H were placed either over or under the electrodes using the plasma enhanced chemical vapor deposition (PECVD) technique to provide the substrate with a suitable surface conductivity. By changing the carbon content and boron doping density, the sheet resistance of the a-Si:C:H coating could be successfully controlled in the range of 1012 ∼ 1017 μ/□, and the light sensitivity, which causes the resistivity to vary with ambient light conditions, was minimized. An avalanche gain of 5000 and energy resolution of 20% FWHM were achieved and the gain remained constant over a week of operation. A-Si:C:H film is an attractive alternative to ion-implanted or semiconducting glass due to the wide range of resistivities possible and the feasibility of making deposits over a large area at low cost.

MOCVD OF SnO2 on Silicon Microhotplate Arrays for use un Gas Sensing Applications

1995 ◽  
Vol 415 ◽  
Author(s):  
F. Dimeo ◽  
S. Semancik ◽  
R.E. Cavicchi ◽  
J.S. Suehle ◽  
P. Chaparala ◽  
...  
Keyword(s):  
Thin Films ◽  
Gas Sensing ◽  
Low Cost ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Medical Diagnostics ◽  
Electrical Contacts ◽  
Quantitative Detection ◽  
Sensing Applications ◽  
Resistive Heater

ABSTRACTThe quantitative detection of gas concentrations in mixed atmospheres is becoming increasingly important in manufacturing processing, environmental monitoring, and medical diagnostics. Several conductive oxides, such as SnO2, ZnO, and TiO2, are well known to exhibit changes in resistivity when exposed to various gases at temperatures ranging from 200–500°C. Current discrete devices based on resistive changes such as the Taguchi sensor, however, suffer from certain performance problems, including poor gas detection specificity. Integrated arrays of sensors, fabricated using planar technology, offer a promising solution to these problems, as well as other benefits such as low power consumption and low cost.In this paper, we report the results of using Metalorganic Chemical Vapor Deposition (MOCVD) to fabricate thin films of SnO2 on microhotplate arrays. The studied arrays contain 4 micromachined, suspended elements, each having an integrated resistive heater that produces a rapid thermal rise time ∼3 msec. By separately heating individual elements, we can take advantage of the thermally selective nature of the MOCVD process to limit deposition to these areas, resulting in a maskless deposition process. In addition, these array elements have surface electrical contacts that permit the measurement of the resistance of the thin films during deposition, as well as when they are operated in a gas sensing mode. In situ growth measurements will be reported.

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