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1 – 6 of 6T.S. Dhahi, U. Hashim, M.E. Ali and Nazwa Taib
Nanogap electrodes have important applications in power saving devices, electrochemical sensors and dielectric detections of biomolecules. The purpose of this paper is to…
Abstract
Purpose
Nanogap electrodes have important applications in power saving devices, electrochemical sensors and dielectric detections of biomolecules. The purpose of this paper is to report on the fabrication and characterization of polysilicon nanogap patterning using novelties technique.
Design/methodology/approach
Polysilicon material is used to fabricate the nanogap structure and gold is used for the electrode and two chrome masks are used to complete this work; the first mask for the nanogap pattern and a second mask for the electrode. The method is based on the control of the coefficients (temperature and time) with an improved pattern size resolution thermal oxidation.
Findings
Physical characterization by scanning electron microscopy (SEM) demonstrates such nanogap electrodes could be produced with high reproducibility and precision. Electrical characterization shows that nanogap enhanced the sensitivity of the device by increase the capacitance and the conductivity as well. They have also good efficiency of power consumption with high insulation properties.
Originality/value
With this technique, there are no principal limitations to fabricating nanostructures with different layouts down to several different nanometer dimensions. The paper documents the fabrication of nanogaps electrodes on a polysilicon, using low‐cost techniques such as vacuum deposition and conventional lithography. Polysilicon is a low‐cost materials and has desirable properties for semiconductor applications. A method of preparing a nanogap electrode according to the present innovation has an advantage of providing active surface that can easily be modified for immobilizations of biomolecules.
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T.S. Dhahi, U. Hashim and M.E. Ali
The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these…
Abstract
Purpose
The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these structures to be used in biomolecular sensing devices.
Design/methodology/approach
The authors previously reported the fabrication and morphological characterization of these structures. In this report, they electrically probed the presence of nanogap through current measurement. The effects of electrolytes on the capacitance profiles of these structures were systematically studied with air, water and various dilutions of phosphate buffer saline.
Findings
An increment in capacitance was found with the increment in electrolyte concentration. Improvement in current flow, capacitance, permittivity, and conductivity were observed with the smaller size nanogaps, suggesting their applications in low power consuming devices.
Originality/value
Since nanogap‐based dielectric biosensing devices need to be operated with a low level of current to avoid biomolecular damage, these structures should have potential applications in dielectric‐based biomolecular detection using a low cost dielectric analyser.
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Yijun Teh, Asral Bahari Jambek and Uda Hashim
This paper aims to discuss a nanoscale biosensor and its signal analysis algorithms.
Abstract
Purpose
This paper aims to discuss a nanoscale biosensor and its signal analysis algorithms.
Design/methodology/approach
In this work, five nanoscale biosensors are reviewed, namely, silicon nanowire field-effect-transistor biosensors, polysilicon nanogap capacitive biosensors, nanotube amperometric biosensors, gold nanoparticle-based electrochemical biosensors and quantum dot-based electrochemical biosensors.
Findings
Each biosensor produces a different output signal depending on its electrical characteristics. Five signal analysers are studied, with most of the existing signal analyser analyses based on the amplitude of the signal. Based on the analysis, auto-threshold peak detection is proposed for further work.
Originality/value
Suitability of the signal processing algorithm to be applied to nano-biosensors was reported.
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Roungdao Klinjapo, Kamonchanok Areerat and Pornpong Sutthirak
The purpose of this paper is to investigate the potential of fruit waste materials from fruit industry as sources of powerful natural antioxidants.
Abstract
Purpose
The purpose of this paper is to investigate the potential of fruit waste materials from fruit industry as sources of powerful natural antioxidants.
Design/methodology/approach
The peels of mango, rambutan, and santol were extracted and analyzed for their antioxidant activity. Pork ball samples were prepared and treated with different natural extracts at various concentrations, namely 0.05, 0.10, 0.15, and 0.20% (v/w), compared with the control (no natural extract), and then stored at 4°C. The samples were investigated at the zeroth, third, fifth, eighth and tenth day to find out the antioxidant activity of the total phenolic content and lipid oxidation including the evaluation of the change of rancid flavor and color during storage. All statistical results were analyzed by RCBD using SPSS at p⩽0.05.
Findings
During storage, the amount of phenolic compound in a pork ball by adding fruit extracts at various concentrations slightly decreased, while the lipid oxidation slightly increased. Mango extract showed the best efficiency to delay lipid oxidation in the pork ball for ten days followed by santol extract and rambutan extract. For sensory evaluation, the pork ball with fruit extract at various concentrations showed the lower rancidity development than control, and mango extract at 0.20% (v/w) showed the best delaying rancidity during ten-day storage. Thus, mango peel extract at 0.20% (v/w) showed the highest effectiveness of antioxidant activity against lipid oxidation in pork ball.
Originality/value
This study was continued from the previous research which investigated the best extraction condition for by-products of mango, rambutan, and santol. From that study, the authors found that the crude extracts need further research on their antioxidant property in foods. The research findings have provided information regarding the interesting new natural antioxidant that can be applied into lipid-containing foods to delay the rancidity and extend the shelf life.
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Uda Hashim, Nazwa Taib, Thikra S. Dhahi and Azizullah Saifullah
Nanobiosensors based on nanogap capacitor are widely used for measuring dielectric properties of DNA, protein and biomolecule. The purpose of this paper is to report on…
Abstract
Purpose
Nanobiosensors based on nanogap capacitor are widely used for measuring dielectric properties of DNA, protein and biomolecule. The purpose of this paper is to report on the fabrication and characterization polysilicon nanogap patterning using novelties technique.
Design/methodology/approach
Overall, the polysilicon nanogap pattern was fabricated based on conventional lithographic techniques. For size expansion technique, by employing simple dry thermal oxidation, the couple of nanogap pattern has been expanded to lowest nanogap value. The progress of nanogap pattern expansion was verified by using scanning electron microscopy (SEM). Conductivity, resistivity, and capacitance test were performed to characterize and to measure electrical behavior of full device fabrication.
Findings
SEM characterization emphasis on the expansion of polysilicon nanogap pattern increasing with respect to oxidation time. Electrical characterization shows that nanogap enhanced the sensitivity of the device at the value of nano ampere of current.
Originality/value
These simple least‐cost method does not require complicated nanolithography method of fabrication but still possible to serve as biomolecular junction. This approach can be applied extensively to different design of nanogap structure down to several nanometer levels of dimensions. A method of preparing a nanogap electrode according to the present innovation has an advantage of providing active surface that can be easily modified for immobilizations of biomolecules.
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The purpose of this study is to present reports on fabrication of silicon (Si) nanowires (NWs). The study consists of microwire formation on silicon-on-insulator (SOI…
Abstract
Purpose
The purpose of this study is to present reports on fabrication of silicon (Si) nanowires (NWs). The study consists of microwire formation on silicon-on-insulator (SOI) that was fabricated using a top-down approach which involved conventional photolithography coupled with shallow anisotropic etching.
Design/methodology/approach
A 5-inch p-type silicon-on-insulator (SOI) coated with 250nm layer and Photoresist (PR) with thickness of 400nm is coated in order to make pattern transfer via binary mask, after the exposure and development, a resist pattern between 3 μm-5 μm were obtained, Oxygen plasma spreen was used to reduce the size of the PR to 800 μm, after this, the wafer with 800 μm was loaded into SAMCO inductively coupled plasma (ICP)-RIE and got silicoon microwire was obtained. Next, the sample was put into an oxidation furnace for 15, 30, 45 and 60 minutes and the sample was removed and dipped into a buffered oxide etch solution for five minutes to remove all the SiO2 ashes.
Findings
The morphological characterization was conducted using scanning electron microscopy and atomic force microscopy. At terminal two, gold electrodes which were designated as source and drain were fabricated on top of individual NWs using conventional lithography electrical and chemical response. Once the trimming process has been completed, the device's current–voltage (I-V) characteristic was measured by using a Keithley 4200 semiconductor parameter analyser. Devices with different width of wires approximately 20, 40, 60 and 80 nm were characterized. The wire current variation as a function of the pH variation in voltage was investigated: pH monitoring for variations of pH values between 5 and 9.
Originality/value
This paper provides useful information on novel and yet simple cost-effective fabrication of SiNW; as such, it should be of interest to a broad readership, especially those interested in micro/nanofabrication.
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