Papers by Author: M.Rizwan Malik

Abstract: Engineering medical applications are enriched by the fabrication potential of the growing technology of Micro-Electro-Mechanical Systems (MEMS). Within this technological expansion, device manufacturing costs, failure and long-term performance reliability are critical issues that have to be resolved using basic probabilistic design methodologies which are yet largely unexploited by industrial and service companies at the mature innovation level. Modeling and testing of high-performance MEMS is a promising route, based upon these methodologies, to enhancing reliability and preventing surface failure. In this paper, we focus on the modeling of the mechanical properties of MEMS, as exemplified by a capacitive accelerometer, using probabilistic techniques. The accuracy of these techniques is also evaluated for the accelerometer with regard to those parameters that affect mainly reliability and failure. The simulated analysis of the mechanical properties is performed with easy-to-use probabilistic software known as “NESSUS”. It is concluded that probabilistic design methodologies are very effective and balanced for making design decisions that can, with both reliability and ease, ensure component or system efficiency.

Abstract: Micro/nano outcrops generated on hydrophobic surfaces are vital outcomes of the super-hydrophobic mechanism in the fabrication of miniature batteries, super-capacitors, field effect transistors and electrochemical and biological sensors. In systematized posts positioned on superhydrophobic surfaces, it is critical to alter the contact angle, whilst the retreating one depends upon the post size and spacing. In this paper, it is shown that calculation of the apparent surface free energy concerned with the probe liquid surface tension, and both advancing and receding contact angles (a and r respectively), is useful for bringing special attention to shedding more light on the wetting properties of superhydrophobic surfaces. A simulation is performed, in order to present this interesting phenomenon, which is in reasonable agreement with experiment. It is concluded that the computation supports categorizing the wetting phenomena as well as encouraging further progress in the fabrication of MEMS/NEMS structures with high efficiency, degree of precision, accuracy, uniformity, aspect ratio and through-put.

Abstract: Carbon-MEMS (C-MEMS) have emerged as a new category of devices for micro/nano technology with many potential applications. Dielectrophoretic manipulation of micro/nanoparticles with C-MEMS is studied in this paper. Through electric field distribution modeling in carbon electrode array, we analyze the strongest simulation effect results of electric field in three dimensional (3-D) surface plots depicting the magnitude of electric field in various cross sections at different heights above the channel floor for 2, 10, 30 and 50 μm high carbon electrodes. It is represented here that maximum intensity of electric field generates with the equality between the height above the channel floor and the height of the electrodes. Simulation parameters involved are for dielectrophoretic manipulation of micro/nano particles based on 3-D C-MEMS. The advantages of using 3-D C-MEMS electrodes over other techniques of creating high-throughput systems for dielectrophoretic manipulation environment surrounded by micro/nano horizons are: (i) complex microscale 3-D electrodes with high-aspect ratios can easily be shaped and patterned using conventional lithography (ii) carbon has a high window of stability thus allowing application of higher voltages (iii) there is no need for bulk micromachining or patterning electrodes on multiple planes (iv) the distance between electrodes can precisely be controlled through the lithography process. FEMLAB 3.4 Multiphysics Modeling software (COMSOL, Stockholm, Sweden) is used for the modeling of electric fields and one-layer C-MEMS microelectrode array was fabricated with SU-8 photoresist.