Abstract: A CMOS compatible integrated MEMS process for fabricating differential capacitance based sensor on SOI wafer is presented. High aspect ratio features are etched in the device layer of SOI wafer and are electrically isolated from each other and circuit elements except where interconnection is required using isolation trenches. The Isolation trenches are first etched on device Si to electrically isolate static combs while maintain the mechanical connection. This scheme results in high sense capacitance with increased SNR. Various considerations which need to be addressed for fabricating the isolation trenches are presented in this paper and the results using the example of an accelerometer are presented. Various isolation trench ends are designed and fabricated and the results are discussed.
Abstract: There are high interests among the researchers and industries for effective deposition of thick layer liquid photo-resists with applications such as fabrication of microfluidics and polymeric membranes using lithography. In this paper, we study performance of different techniques of coating for thick layers of SU-8 using spin coating, self planarization and a technique of sandwiching the resin between two parallel solid plates. Deposition using spin coaters for SU-8 2075 is limited hardly to around 250 µm with some irregularities such as edge-beads. Self-planarization requires enough resting time. We have achieved a thickness of around 1 mm in a single coating but is limited to only thick layers in reasonable time. The sandwich technique can be used for any thickness and is very fast. We present here a comparison of the three mentioned methods according to our observed data of the coating time, uniformity of the coating surface and capability of coating thick layers for a high viscosity SU-8 2075 that is employed in fabrication of microfluidics micro-structures.
Abstract: Platinum (Pt) thin film microheater is designed for integration in a well-known dog bone-like microtensile test structure for high temperature tensile properties measurement. COMSOL Multiphysics tool with electro-thermal modeling was employed to predict the Joule heating capability of three different configurations of Ptmicroheater. The temperature of the test structure resulted from the three micorheater configurations as a function of total dissipated power was plotted for comparison. The microheater with the dendritic-like configuration was found to have the highest power efficiency of 3.19°C/mW in heating up the microtensile test structure.
Abstract: Micro-cantilever has been proven as an outstanding platform for extremely sensitive chemical and biological sensors. MEMS cantilever-based sensor is becoming popular due to its high sensitivity, high selectivity, easy to fabricate and can be easily integrated with on-chip electronics circuitry. However, the interface circuit used in this kind of sensors typically has a very low resolution and this limits its capability in sensing the small signal generated by the micro-cantilever. One solution is by incorporating stress concentration regions (SCR) on the micro-cantilever which were found to improve the sensitivity of the sensor. This project will focus on optimizing the sensitivity of the micro-cantilever by modeling the micro-cantilever with the SCR technique. The model is then be verified by numerical simulations.
Abstract: A 100GHz planar helix with straight-edge connections slow-wave structure incorporating coplanar waveguide feed has been designed and fabricated. The proposed fabrication process can produce high-aspect-ratio planar helical structures which is essential for sheet electron beam traveling-wave tube application. The photoresists used in this process can be easily stripped after electroplating of three-dimensional structures.
Abstract: In this paper, a new estimation method is proposed to estimate the separation gap and other unknown parameters in Casimir force actuated systems. Real experimental conditions like the finite conductivity and surface roughness are considered as well. Simulation study shows that the method is accurate even when the system has severe nonlinearity.
Abstract: A static micromixer having a fractal-like structure is proposed inspired from natural flow networks. The mixing behavior of flow in this micromixer is investigated using numerical and experimental approaches. This converging flow network is basically using the mechanisms of fluid multilamination for mixing enhancement. Simulations are made on the flow behavior to investigate the effect of branching numbers, hierarchy levels, geometrical sizes and other design parameters using FEM methods. A rapid prototyping system for microfluidics using PDMS molding technology was successfully utilized to fabricate the designed multichannel micromixer. Experimentally, image processing technique was used to characterize flow and mixing quality in the microfluidic structure. Obtained results from numerical simulation and experimental measurements are compared with a single channel with equal flow length using the mixing quality index. This improved micromixer can further be optimized in terms of fractal shapes and numbers and geometrical size for specific applications.
Abstract: This paper presents a novel piezoelectric actuator design that achieves low curling due to residual film stress. The proposed actuator maintains the gap between the movable electrode and the fixed electrode nearly constant independent of the residual stress level, improving the reproducibility and reliability of piezoelectric devices. At 20V excitation, the actuator deflects more than 5 µm. The design also achieves a capacitor electrode around 6% of the total actuator area, which is 2.5 times greater than other reported designs. This paper demonstrates the novel actuator in a tunable capacitor, but the actuator may be used in many other applications, such as MEMS switches and micro-mirrors.
Abstract: We propose a concept for a novel ‘innervated’ material that is assembled by addition of a multitude of MEMS to a conventional material. This approach shall enable the material to show specific reactions to external inputs, and make the reaction accessible to external observers. By implementing such innervated material into buildings, clothing or even food, it would be possible to create a virtual neural system in objects. This work introduces the concept, gives an outlook on the potential of such an approach in art, science and technology and the possible impact on the life of future generations.