scholarly journals Fabrication of nano-patterns of photoresist by ultraviolet lithography and oxygen plasma

2020 ◽  
Vol 71 (5) ◽  
pp. 359-364
Author(s):  
E Cheng ◽  
Suzhou Tang ◽  
Helin Zou ◽  
Zhengyan Zhang ◽  
Yao Wang
Keyword(s):  
Oxygen Plasma ◽  
Treatment Time ◽  
Low Cost ◽  
Two Dimensional ◽  
Rf Power ◽  
Simple Method ◽  
Ultraviolet Lithography ◽  
Nanofluidic Devices ◽  
Bottom Width ◽  
Time Division

Abstract Nanofluidic devices with two-dimensional nanochannels have many applications in biology and chemistry, however, it is still a challenge to develop a low-cost and simple method for fabricating nano-masks that can be used to produce two-dimensional nanochannels. In this paper, a novel low-cost and simple method, based on UV lithography and oxygen plasma, was proposed to fabricate nano-mask. The influence of exposure time on the photoresist mesas was investigated in the ultraviolet lithography process. The parameters of RF power and treatment time on the width reduction of photoresist mesas were analyzed by the oxygen plasma. In our work, in order to increase the efficiency controllability of photoresist removal, a RF power of 90 W, a pressure of oxygen plasma 60 Pa, and the time division method were adopted to remove photoresist by oxygen plasma. Finally, nano-patterns of photoresist mesas with bottom width of 330 nm were successfully fabricated. The proposed method provides a low-cost way to produce high-throughput two-dimensional nanochannels.

Nano-Gaps Fabricated by Thermal Evaporation and Stripping Techniques

2021 ◽  
Vol 21 (9) ◽  
pp. 4852-4856
Author(s):  
E Cheng ◽  
Suzhou Tang ◽  
Helin Zou ◽  
Guochao Qiao ◽  
Zhengyan Zhang
Keyword(s):  
Silicon Substrate ◽  
Metal Film ◽  
Thermal Evaporation ◽  
Low Cost ◽  
Adhesive Force ◽  
Metal Films ◽  
Two Dimensional ◽  
Structural Morphology ◽  
Simple Method

The fabrication of inexpensive nano-gaps is vitally important for the research and application of nanochannel-based devices. This study presents a low-cost and simple method for the fabrication of nano-gaps using thermal evaporation and stripping techniques. The structural morphology of metal films deposited on the convex structures of photoresist by sputtering and thermal evaporation was studied. The effect of angles of thermal evaporation on the width of nano-gaps was investigated. The characteristics of metal film deposited on the convex structures of photoresist and spaces between these convex structures after stripping were investigated, and the adhesive force between the metal film and silicon substrate was also analyzed. Finally, a metal film of Cu was deposited on the convex structures of photoresist by thermal evaporation. After stripping, nano-gaps with a width of 187 nm were fabricated. The method proposed in this paper can be employed to mass-produce two-dimensional nanochannels based devices at low cost.

A NOVEL FABRICATION METHOD OF TWO-DIMENSIONAL NANO-MOLD BY COMBINING ULTRAVIOLET LITHOGRAPHY WITH WET ETCHING TECHNOLOGY

2020 ◽  
pp. 2050028
Author(s):  
E CHENG ◽  
SUZHOU TANG ◽  
LINGPENG LIU ◽  
HELIN ZOU ◽  
ZHENGYAN ZHANG
Keyword(s):  
Low Cost ◽  
Wet Etching ◽  
Etching Time ◽  
Two Dimensional ◽  
Cross Sectional ◽  
Ultraviolet Lithography ◽  
Uv Lithography ◽  
Fluidic Devices ◽  
Mold Fabrication

Nano-fluidic devices have great potential in the applications of biology, chemistry, and medicine. However, their applications have been hampered by their expensive or complicated fabrication methods. We present a new and simple approach to fabricate low-cost two-dimensional (2D) nano-mold based on ultraviolet (UV) lithography and wet etching. The influence of UV lithography parameters on the width dimension of AZ5214 photoresist was investigated. With the optimized parameters of UV lithography, the width dimension of photoresist patterns had sharply decreased from microscale to nano-scale. At the same time, the influences of etching time on the over-etching amount of SiO2 film and nano-mold depth were also analyzed for further reducing the width of nano-mold. In addition, the effect of photoresist mesas deformation on the nano-mold fabrication was also studied for improving the quality of nano-mold. By the proposed method, trapezoid cross-sectional 2D nano-mold with different dimensions can be obtained for supporting varied applications. The minimum nano-mold arrays we fabricated are the ones with the dimensions of 115[Formula: see text]nm in top edge, 284[Formula: see text]nm in bottom edge, and 136[Formula: see text]nm in depth. This method provides a low-cost way to fabricate high-quality and high-throughput 2D nano-mold.

scholarly journals Applying Heat and Humidity using Stove Boiled Water for Decontamination of N95 Respirators in Low Resource Settings

2020 ◽  
Author(s):  
Siddharth Doshi ◽  
Samhita Banavar ◽  
Eliott Flaum ◽  
Shailabh Kumar ◽  
Tyler Chen ◽  
...  
Keyword(s):  
Large Scale ◽  
Treatment Time ◽  
Low Cost ◽  
Simple Method ◽  
Low Resource Settings ◽  
Low Resource ◽  
Moist Heat ◽  
Reported Data ◽  
N95 Respirators ◽  
Boiled Water

AbstractGlobal shortages of N95 masks have led to an urgent need of N95 decontamination and reuse methods that are scientifically validated and available globally. Although several large scale decontamination methods have been proposed (hydrogen peroxide vapor, UV-C); many of them are not applicable in remote and low resource settings. Heat with humidity has been demonstrated as a promising decontamination approach, but care must be taken when implementing this method at a grassroots level. Here we present a simple method to provide stable humidity and temperature for individual N95 masks which can be simply scaled in low resource settings. Moist heat (>50% humidity, 65-80C temperature) was applied to Kimberly-Clark N95 respirators for over 30 minutes by placing sealed containers with N95 respirators into water that had been brought to a rolling boil and removed from heat, and then allowing the containers to sit for over 45 minutes. After rising to their threshold points, temperature and humidity remained above 65C and 50% for a treatment time of at least 30 minutes. Filtration efficiency of 0.3-4.99um particles remained above 97% after 5 treatment cycles across all particle size sub-ranges, which is consistent with previously-reported data for similar heat and humidity conditions on different N95 FFR models. Although no fit tests were conducted on these masks after treatment, prior data on moist heat based treatment indicates consistent fit for up to five cycles of decontamination. This method of applying heat and humidity for the purpose of N95 respirator decontamination can be implemented on open flame stoves for low resource settings without reliable electricity access or where other methods of decontamination are not accessible. Higher temperatures or longer treatment times, such as treatment at >70C for over 30 minutes, could be achieved by increasing the volumes of boiled water used. Although fresh N95 masks should always be used - whenever available - we believe this simple yet reliable method provides a low cost, electricity free method for N95 decontamination in remote parts of the world.

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

A simple method to construct a low-cost immunosensor based on a dithiol-functionalized polydopamine platform

2021 ◽  
Author(s):  
Bo Liu ◽  
Luanying Yang ◽  
Gang Wang ◽  
Sha He ◽  
Xiaobo Wang ◽  
...  
Keyword(s):  
Detection Limit ◽  
Linear Response ◽  
Low Cost ◽  
Covalent Immobilization ◽  
The Self ◽  
Simple Method ◽  
Low Detection Limit

A simple and low-cost electrochemical CEA immunosensor was investigated via the self-polymerization of dopamine and a dithiol compound spacer for the covalent immobilization of antibodies. The designed CEA immunosensor exhibited a linear response and a low detection limit.

scholarly journals Physical-Layer Security Improvement with Reconfigurable Intelligent Surfaces for 6G Wireless Communication Systems

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1439
Author(s):  
Janghyuk Youn ◽  
Woong Son ◽  
Bang Chul Jung
Keyword(s):  
Wireless Communication ◽  
Physical Layer Security ◽  
Communication Systems ◽  
Low Cost ◽  
Physical Layer ◽  
Base Station ◽  
Wireless Communication Systems ◽  
Secrecy Rate ◽  
Pilot Signal ◽  
Time Division

Recently, reconfigurable intelligent surfaces (RISs) have received much interest from both academia and industry due to their flexibility and cost-effectiveness in adjusting the phase and amplitude of wireless signals with low-cost passive reflecting elements. In particular, many RIS-aided techniques have been proposed to improve both data rate and energy efficiency for 6G wireless communication systems. In this paper, we propose a novel RIS-based channel randomization (RCR) technique for improving physical-layer security (PLS) for a time-division duplex (TDD) downlink cellular wire-tap network which consists of a single base station (BS) with multiple antennas, multiple legitimate pieces of user equipment (UE), multiple eavesdroppers (EVEs), and multiple RISs. We assume that only a line-of-sight (LOS) channel exists among the BS, the RISs, and the UE due to propagation characteristics of tera-hertz (THz) spectrum bands that may be used in 6G wireless communication systems. In the proposed technique, each RIS first pseudo-randomly generates multiple reflection matrices and utilizes them for both pilot signal duration (PSD) in uplink and data transmission duration (DTD) in downlink. Then, the BS estimates wireless channels of UE with reflection matrices of all RISs and selects the UE that has the best secrecy rate for each reflection matrix generated. It is shown herein that the proposed technique outperforms the conventional techniques in terms of achievable secrecy rates.

scholarly journals Microfabrication with Very Low-Average Power of Green Light to Produce PDMS Microchips

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 607
Author(s):  
Lucero M. Hernandez-Cedillo ◽  
Francisco G. Vázquez-Cuevas ◽  
Rafael Quintero-Torres ◽  
Jose L. Aragón ◽  
Miguel Angel Ocampo Mortera ◽  
...  
Keyword(s):  
Low Cost ◽  
Average Power ◽  
Green Light ◽  
Microfluidic Devices ◽  
Processing Parameters ◽  
Coating Film ◽  
Two Dimensional ◽  
Dimethyl Siloxane ◽  
Visible Laser ◽  
High Absorption

In this article, we show an alternative low-cost fabrication method to obtain poly(dimethyl siloxane) (PDMS) microfluidic devices. The proposed method allows the inscription of micron resolution channels on polystyrene (PS) surfaces, used as a mold for the wanted microchip’s production, by applying a high absorption coating film on the PS surface to ablate it with a focused low-power visible laser. The method allows for obtaining micro-resolution channels at powers between 2 and 10 mW and can realize any two-dimensional polymeric devices. The effect of the main processing parameters on the channel’s geometry is presented.

scholarly journals A set of simple methods for detection and extraction of laminarinase

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ananthamurthy Koteshwara ◽  
Nancy V. Philip ◽  
Jesil Mathew Aranjani ◽  
Raghu Chandrashekhar Hariharapura ◽  
Subrahmanyam Volety Mallikarjuna
Keyword(s):  
Ammonium Sulfate ◽  
Ammonium Sulphate ◽  
Gold Standard ◽  
Direct Detection ◽  
Low Cost ◽  
Direct Analysis ◽  
Reducing Sugar ◽  
Ammonium Sulfate Precipitation ◽  
Simple Method ◽  
Functional Step

AbstractA carefully designed ammonium sulfate precipitation will simplify extraction of proteins and is considered to be a gold standard among various precipitation methods. Therefore, optimization of ammonium sulfate precipitation can be an important functional step in protein purification. The presence of high amounts of ammonium sulphate precludes direct detection of many enzymatically active proteins including reducing sugar assays (e.g. Nelson-Somogyi, Reissig and 3,5-dinitrosalicylic acid methods) for assessing carbohydrases (e.g. laminarinase (β (1–3)-glucanohydrolase), cellulases and chitinases). In this study, a simple method was developed using laminarin infused agarose plate for the direct analysis of the ammonium sulphate precipitates from Streptomyces rimosus AFM-1. The developed method is simple and convenient that can give accurate results even in presence of ammonium sulfate in the crude precipitates. Laminarin is a translucent substrate requiring the use of a stain to visualize the zones of hydrolysis in a plate assay. A very low-cost and locally available fluorescent optical fabric brightener Tinopal CBS-X has been used as a stain to detect the zones of hydrolysis. We also report simple methods to prepare colloidal chitin and cell free supernatant in this manuscript.

scholarly journals Two-Dimensional Visualization of the Three-Dimensional Planned Sacroiliac Screw Corridor with the Slice Fusion Method

2021 ◽  
Vol 10 (2) ◽  
pp. 184
Author(s):  
Maximilian Kerschbaum ◽  
Siegmund Lang ◽  
Florian Baumann ◽  
Volker Alt ◽  
Michael Worlicek
Keyword(s):  
Pelvic Ring ◽  
Three Dimensional ◽  
Fusion Method ◽  
Two Dimensional ◽  
Posterior Pelvic Ring ◽  
Simple Method ◽  
Sacroiliac Screw ◽  
Screw Insertion ◽  
Multiplanar Reconstructions ◽  
Screw Position

Insertion of sacro-iliac (SI) screws for stabilization of the posterior pelvic ring without intraoperative navigation or three-dimensional imaging can be challenging. The aim of this study was to develop a simple method to visualize the ideal SI screw corridor, on lateral two-dimensional images, corresponding to the lateral fluoroscopic view, used intraoperatively while screw insertion, to prevent neurovascular injury. We used multiplanar reconstructions of pre- and postoperative computed tomography scans (CT) to determine the position of the SI corridor. Then, we processed the dataset into a lateral two-dimensional slice fusion image (SFI) matching head and tip of the screw. Comparison of the preoperative SFI planning and the screw position in the postoperative SFI showed reproducible results. In conclusion, the slice fusion method is a simple technique for translation of three-dimensional planned SI screw positioning into a two-dimensional strict lateral fluoroscopic-like view.

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