The design and simulation of a planar microarray dot electrode for a dielectrophoretic lab-on-chip device

Dielectrophoresis (DEP) has been proven as a method of manipulating and analyzing the electrophysiological properties of bioparticles by applying non-uniform electric fields generated through special electrodes. Various electrode geometries have been developed to address different applications. Electric field simulation over electrodes is essential in order to optimize the generated DEP force for cell manipulation. This paper describes the study of electric field distribution over planar multiple microarray dot electrodes using numerical modeling of Comsol Multiphysics 4.2a®. Electric field evaluation for different dot sizes has been demonstrated by applying a range of frequencies to the designed electrodes. Results show that the electric field is axisymmetrical around the center of the dot aperture and that it is higher at the dot edges than the dot centers. Furthermore, adding ground plane between adjacent dots increases the electric field strength. © 2012 by ESG

The first decade of biomedical engineering degree program at the University of Malaya: experiences and achievements

The Department of Biomedical Engineering, at the Faculty of Engineering, University of Malaya was established in the 1997/1998 academic session with an intake of 20 students and five academic staff. The Department has undergone numerous changes in the structure of its degree programme, with each one of them recognised and fully accredited by the Engineering Accreditation Council and Ministry of Higher Education. The Department has played an active role at national and global levels, in the areas of biomedical engineering education and research collaboration. Several initiatives have been planned to ensure the Department stays at the forefront of disseminating biomedical engineering innovations in Malaysia

Morphology optimization of highly oriented carbon nanotubes for bioengineering applications

The remarkable properties of high oriented vertically aligned carbon nanotubes make them attractive for bioengineering applications. In this paper, we describe a process of growing long oriented CNTs arrays to improve the electrical properties of subsequent devices based on CNTs. Chemical vapour deposition (CVD) was used to deposit highly oriented CNTs with camphor oil as its carbon source, and argon as its carrier gas to grow perpendicular CNTs on the surface of a silicon substrate in the presence of ferrocene as a metallic catalyst. Images taken by the field emission electron microscopy (FESEM) indicate that the formation mechanism of oriented CNTs, with high morphological purity of nanotubes, depends significantly on the deposition time and applied temperature to the furnaces. This method might be an effective method to produce highly oriented multiwall carbon nanotubes at different aspect ratios

The design and simulation of a planar microarray dot electrode for a dielectrophoretic lab-on-chip device

Dielectrophoresis (DEP) has been proven as a method of manipulating and analyzing the electrophysiological properties of bioparticles by applying non-uniform electric fields generated through special electrodes. Various electrode geometries have been developed to address different applications. Electric field simulation over electrodes is essential in order to optimize the generated DEP force for cell manipulation. This paper describes the study of electric field distribution over planar multiple microarray dot electrodes using numerical modeling of Comsol Multiphysics 4.2a®. Electric field evaluation for different dot sizes has been demonstrated by applying a range of frequencies to the designed electrodes. Results show that the electric field is axisymmetrical around the center of the dot aperture and that it is higher at the dot edges than the dot centers. Furthermore, adding ground plane between adjacent dots increases the electric field strength. © 2012 by ESG

On the linearity/non-linearity of mental activity EEG for brain-computer interface design

In this study, we investigated the linearity/nonlinearity of mental activity electroencephalogram (EEG) signals for Brain-Computer Interface (BCI) designs using the recent but well established Delay Vector Variance (DVV) method. EEG data recorded from seven subjects while they were performing five different mental activities were used in the experimental study. Through the use of DVV, it was investigated whether EEG signals would become linear or nonlinear when segmented into smaller parts. Concluding, the results of the studies showed that a large percentage of the EEG signals exhibited non-linear behaviour. This is an important result as it shows that the currently used linear modelling methods are mostly unsuitable

Controlling Vaporization Time as Effective Parameter on Purified Vertically Aligned Carbon Nanotubes Based on CVD Method

The unique properties of Carbon nanotubes (CNTs) were determined from 15 years' worth of scientific investigation in the context of multiple applications. Here, we report the effect of time dependent temperature on camphor oil within 500-1150°C of different vaporization times. According to the results, the CNTs growth rate was increased abruptly by increasing vaporization time. This process was conducted in similar conditions by optimizing the temperature to up to 900°C. FESEM images indicate that the highest catalytic activity was achieved at 180°C and 800°C of first and second furnace, respectively, directing the experiment in growing purified CNT to up to 111 μm in length during the 30 minutes reaction time. It was also gleaned from the results that at the lower vaporization time and temperature, the catalyst-support interaction is not completed to allow the metal particles to partake in the deposition process, but in the optimized vaporization process, MWCNTs can be selectively grown as a function of CVD time. The optimum vaporization time was determined to be 30 minutes, which based on the Raman shift results; the grown CNTs exhibited high purity and crystallinity, as well as a desired aspect ratio

Real-time cell electrophysiology using a multi-channel dielectrophoretic-dot microelectrode array

Dielectrophoresis (DEP) has been used for many years for the analysis of the electrophysiological properties of cells. However, such analyses have in the past been time-consuming, such that it can take 30min or more to collect sufficient data to make valid interpretations from a single DEP spectrum. This has limited the application of the technology to a rapid tool for non-invasive, label-free research in areas from drug discovery to diagnostics. In this paper we present the development of a programmable, multi-channel DEP system for rapid biophysical assessment of populations of biological cells. A new assay format has been developed for continuous near-real-time monitoring, using simultaneous application of up to eight alternating current electrical signals to independently addressable dot microelectrodes in an array format, allowing a DEP spectrum to be measured in 20s, with a total cycle time between measurements of 90s. To demonstrate the system, human leukaemic K562 cells were monitored after exposure to staurosporine and valinomycin. The DEP response curves showed the timing and manner in which the membrane properties changed for the actions of these two drugs at the early phase of induction. This technology shows the great potential for increasing our understanding of the role of electrophysiology in drug action, by observing the changes in electrical characteristics as they occur. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Carbon-based nanobiohybrid thin film for amperometric glucose sensing

This pioneering study involved the fabrication of a new class of nanohybrid-based electrochemical glucose biosensor. First, three-dimensional (3D) graphene was fabricated as a platform of multiwalled carbon nanotube (MWCNT). Then, it was used to immobilize glucose oxidase (GOD) on nanohybrid thin film via the entrapment technique. The modified glucose biosensor indicated excellent biocatalytic activity toward the glucose measurment with a sensitivity of up to 49.58 μA mM–1 cm–2 and a wide linear dynamic range up to 16 mM. The fabricated biosensor shows an excellent stability of 87.8%, with its current diminishing after 3 months. This facile and simple electrochemical method for glucose monitoring using a modified glassy carbon electrode (GCE) by 3DG-MWCNT-GOD could open new avenues in producing of a inexpensive and sensitive glucose nanobiosensors.Samira Bagheri, Amin Termehyousefi, Negar Mansouri, Arman Amani Babadi, Mohd Sayuti Abd Karim, and Nahrizul Adib Kadr