Micro-Electro-Mechanical Systems (MEMS) technology

The grinding process commonly used in manufacturing requires a specific surface finish, critical size, and required ground surface. The grinding process is used in order to improve final products 'quality by reducing surface roughness and increasing tolerance integrity. To improve final products quality, it is essential to know which grinding wheel should be used and how to avoid surface burn by getting a better analysis of forces acting on the material. This project is the investigation of the grinding process with respect to the theoretical and experimental methods. Theoretical methods provide the background information about the grinding process, where one can use it, the aim of the grinding process, elements of grinding process and previous results of grinding process done with precise parameters. Theoretical knowledge obtained via journals, library and literature database. Experimental methods will do by simulation on Matlab software and surface grinding operations. Simulation on Matlab software is the methodology to simulate and provide results, which are verisimilitudinous and necessary to eliminate costs and time in the manufacturing process. and provides respectively concurrent results to the grinding process with various types of inputs such as different grinding stones with different grain numbers, grinding wheel size by height and width, thickness, and material. In addition, experimental results were obtained using a surface grinding machine to investigate surface roughness and grinding forces by using various types of grinding stones. Furthermore, abrasive grains' characteristics are being studied, their effect on the grinding process, and the measurement of abrasion.

High sensitivity MEMS pressure sensor chip for different ranges (1 to 60 kPa) utilizing the novel electrical circuit of piezosensitive differential amplifier with negative feedback loop (PDA-NFL) is developed. Pressure sensor chip PDA-NFL utilizes two bipolar-junction transistors (BJT) with vertical n-p-n type structure (V-NPN) and eight piezoresistors (p-type). Both theoretical model of sensor response to pressure and temperature and experimental data are presented. Data confirms the applicability of theoretical model. Introduction of the amplifier allows for decreasing chip size while keeping the same sensitivity as a chip with classic Wheatstone bridge circuit.

Sensor networks are currently an active research area mainly due to the potential of their applications. In this paper we investigate the use of Wireless Sensor Networks (WSN) for air pollution monitoring in Mauritius. With the fast growing industrial activities on the island, the problem of air pollution is becoming a major concern for the health of the population. We proposed an innovative system named Wireless Sensor Network Air Pollution Monitoring System (WAPMS) to monitor air pollution in Mauritius through the use of wireless sensors deployed in huge numbers around the island. The proposed system makes use of an Air Quality Index (AQI) which is presently not available in Mauritius. In order to improve the efficiency of WAPMS, we have designed and implemented a new data aggregation algorithm named Recursive Converging Quartiles (RCQ). The algorithm is used to merge data to eliminate duplicates, filter out invalid readings and summarise them into a simpler form which significantly reduce the amount of data to be transmitted to the sink and thus saving energy. For better power management we used a hierarchical routing protocol in WAPMS and caused the motes to sleep during idle time.

This paper explores the modelling and simulation of a Radio Frequency Micro ElectroMechanical Systems (RF MEMS) switch using Finite Element modelling and analysis (FEM and FEA) tools on a novel seesaw design, providing Double-Pole Double-Throw (DPDT) functionality. This optimises the capabilities of the seesaw design structure for use in mobile communication systems and devices. After researching other available seesaw designs, it was realised that an improvement could be achieved by applying additional contacts within a 3D plane. During the development of the DPDT seesaw switch, a low electrostatic actuation voltage of 14 V was achieved. This provided the switch with improved compatibility with voltages closer to those used in integrated circuits for mobile systems. The switch is a progression of existing Single-Pole Single-Throw (SPST) seesaw switches, with an additional set of upper and lower contacts at each end of the seesaw, offering DPDT switching capability within the space envelope. The length, height and width of the switch is 41 µm, 7.6 µm and of 9 µm respectively, which is a suitable size for fabrication and conforms to the Microscale, from 1 µm to 100 µm. Copper Bulk General (Cu) was chosen for the pivot material on its merits of possessing good electrical conductivity and optimised flexibility and stiffness for elastic recovery. The simulation, using Intellisuite, attained a working switch design, with an ‘Air-Gap’ of 1µm between the contacts, thus providing isolation when the switch is open-circuited.

Materials with intrinsic self-healing phenomenon have the ability to heal in response to external random shocks. Introducing a recovery factor to quantitatively measure the damage self-recovery efficiency, this study designs a self-healing mechanism corresponding to both damage load and shock arrival numbers for a parallel redundant system consisting of multiple non-identical components. From the actual engineering perspective, each shock arriving on the system selectively affects one component or more but not necessarily all units in parallel, and consequently, random shocks are categorized according to their sizes, attributes and affected components. This study investigates novel reliability models and schedules optimal preventive maintenance policies, in which the closed-form reliability quantities are derived analytically and the optimum preventive replacement interval is demonstrated theoretically. In addition, a Nelder-Mead downhill simplex method is introduced to seek the optimal replacement age in minimizing the long-run average maintenance cost rate for the condition system failure distribution is rather complex. A micro-electro-mechanical system (MEMS) whose constitutional materials are integrated by microcrystalline silicon, where polymer binders with self-healing capability are always synthesized, is designed to verify the results we obtained numerically, illustrating the significance of considering damage self-healing phenomena.

High sensitivity MEMS pressure sensor chip for different ranges (1 to 60 kPa) utilizing the novel electrical circuit of piezosensitive differential amplifier with negative feedback loop (PDA-NFL) is developed. Pressure sensor chip PDA-NFL utilizes two bipolar-junction transistors (BJT) with vertical n-p-n type structure (V-NPN) and eight piezoresistors (p-type). Both theoretical model of sensor response to pressure and temperature and experimental data are presented. Data confirms the applicability of theoretical model. Introduction of the amplifier allows for decreasing chip size while keeping the same sensitivity as a chip with classic Wheatstone bridge circuit.