Publications Archives – Page 11 of 13 – Institute of Nano Electronic Engineering

Synthesis of single-walled carbon nanotubes by chemical vapor deposition using sodium chloride support

September 4, 2013 By Editor

Abstract – Bundled single-walled carbon nanotubes (SWCNTs) together with multi-walled carbon nanotubes (MWCNTs) were directly grown on a water-soluble support catalyst that was prepared via sublimation of ferrocene on sodium chloride. The synthesis of nanotubes was carried out at a growth temperature of 700 °C in a combined methane and nitrogen environment of 1:1 volumetric ratio at a total flowrate of 80 ml/min for 1 h in a vertical reactor. Characterization techniques such as scanning electron microscope, transmission electron microscope, thermogravimetric analysis, and Raman spectroscopy were employed to study the carbon deposits. Transmission electron microscope shows the presence of SWCNTs with an average diameter of ca. 1.18 nm on the catalyst. The radial breathing mode (RBM) of Raman for shifts below 350 ^-1cm further confirmed the presence of SWCNTs and the diameters were calculated to be 0.93, 1.36, 1.5 and 1.85nm.

Keywords – Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Electron microscopy, Raman spectroscopy

Corresponding Author: Liu Wei Wen
Corresponding Author’s Email: wwliu@unimap.edu.my

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Aptamer-based biosensor for sensitive PDGF detection using diamond transistor

May 2, 2013 By Editor

Abstract – The detection of platelet-derived growth factor (PDGF) via a solution-gate field-effect transistor (SGFET) has been demonstrated for the first time using aptamers immobilized on a diamond surface. Upon introduction of PDGF to the immobilized aptamer, a shift of 31.7mV in the negative direction is observed at a source-drain current of −50µA. A shift of 32.3mV in the positive direction is detected after regeneration by SDS solution, indicating that the static measurement returns to its original value. These SGFETs operate stably within the large potential window of diamond (>3.0 V), and hence the surface channel does not need passivating with a thick insulating layer. Thereof, the immobilized aptamer channels have been exposed directly to the electrolyte solution without a gate insulator. Immobilization is achieved via aptamers covalently bonding to amine sites, thereby increasing the sensitivity of the biosensors. Diamond SGFETs have potential for the detection of PDGF and show durability against biological degradation after repeated usage and regeneration.

Keywords – Aptamer, Diamond transistor, Platelet-derived growth factor, Biosensor

Corresponding Author: Ruslinda Abdul Rahim
Corresponding Author’s Email: ruslinda@unimap.edu.my

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Effects of diamond-FET-based RNA aptamer sensing for detection of real sample of HIV-1 Tat protein

April 29, 2013 By Editor

Abstract – Diamond is a promising material for merging solid-state and biological systems owing to its chemical stability, low background current, wide potential window and biocompatibility. The effects of surface charge density on human immunodeficiency virus type 1 Trans-activator transcription (HIV-1 Tat) protein binding have been investigated on a diamond field-effect transistor (FET) using ribonucleic acid (RNA) aptamers as a sensing element on a solid surface. A change in the gate potential of 91.6 mV was observed, whereby a shift in the negative direction was observed at a source-drain current of -8µA in the presence of HIV-1 Tat protein bound to the RNA aptamers. Moreover, the reversible change in gate potential caused by the binding and regeneration cycles was very stable throughout cyclical detections. The stable immobilization is achieved via RNA aptamers covalently bonded to the carboxyl-terminated terephtalic acids on amine sites, thereby increasing the sensitivity of the HIV-1 Tat protein sensor. The reliable use of a real sample of HIV-1 Tat protein by an aptamer-FET was demonstrated for the first time, which showed the potential of diamond biointerfaces in clinical biosensor applications.

Keywords – RNA aptamer, Diamond FET, HIV-1 Tat protein, Biosensor

Corresponding Author: Ruslinda Abdul Rahim
Corresponding Author’s Email: ruslinda@unimap.edu.my

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Nanotechnology development status in Malaysia: Industrialization Strategy and Practices

April 25, 2013 By Editor

Abstract – Malaysia has started it own micro-technology and nanotechnology development since the early millennium year of 2000 and arise until this day. Some key plans have proven effective and others fairly not. Status about strategies and practices planned in Malaysia with some relevant finding through experiences in industries collaboration observations and UniMAP involvement in nanotechnology are presented in this paper. Some suggestion and ideas are also presented.

Keywords – Nanotechnology, R&D, Industry, Strategy, Practice, Malaysia.

Corresponding Author: Prof. Dr. Uda Hashim
Corresponding Author’s Email: uda@unimap.edu.my

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New optical features to enhance solar cell performance based on porous silicon surfaces

April 18, 2013 By Editor

Abstract – Electrochemical etching is used to fabricate porous silicon (PS) surfaces for both sides of the Si wafer. The effect of PS on performance of Si solar cells is investigated and the reflected mirrors are manipulated to enhance solar cell efficiency. The process is promising for solar cell manufacturing due to its simplicity, lower cost and suitability for mass production. The PS surface has discrete pores and short-branched pores on the polished wafer side. In contrast, the etched backside of the wafer has smaller pore size, with random pores. PS formed on both sides has lower reflectivity value compared with results in other works. Solar cell efficiency is increased to 15.4% with PS formed on both sides compared with the unetched sample and other results. Using empirical models, the optical properties of the refractive index and the optical dielectric constant are investigated. The porous surface texturing properties could enhance and increase the conversion efficiency of porous Si solar cells. The obtained results are in agreement with experimental and other data.

Keywords – Porous silicon, Solar cell, Crystalline silicon, Refractive index

Corresponding Author: Prof. Dr. Yarub Al-Douri
Corresponding Author’s Email: yarub@unimap.edu.my

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