Dynamic simulation of a peristaltic micropump considering coupled fluid flow and structural motion

This paper presents lumped-parameter simulation of dynamic characteristics of peristaltic micropumps. The pump consists of three pumping cells connected in series, each of which is equipped with a compliant diaphragm that is electrostatically actuated in a peristaltic sequence to mobilize the fluid. Diaphragm motion in each pumping cell is first represented by an effective spring subjected to hydrodynamic and electrostatic forces. These cell representations are then used to construct a system-level model for the entire pump, which accounts for both cell- and pump-level interactions of fluid flow and diaphragm vibration. As the model is based on first principles, it can be evaluated directly from the device's geometry, material properties and operating parameters without using any experimentally identified parameters. Applied to an existing pump, the model correctly predicts trends observed in experiments. The model is then used to perform a systematic analysis of the impact of geometry, materials and pump loading on device performance, demonstrating its utility as an efficient tool for peristaltic micropump design

Development of low frequencies, insulating thick diaphragms for power MEMS applications

Major challenges of micro thermal machines are the thermal insulation and mechanical tolerance in the case of sliding piston. Switching from piston to membrane in microengines can alleviate the latest and lead to planar architectures. However, the thermal isolation would call for very thick structures which are associated to too high resonant frequencies which are detrimental to the engine performances. A thermal and mechanical compromise is to be made. On the contrary, based on fluid structure interaction, using an incompressible fluid contained in a cavity sealed by deformable diaphragm it would be possible to design a thick, low frequency insulating diaphragm. The design involves a simple planar geometry that is easy to manufacture with standard microelectronics methods. An analytical fluid structure model is proposed and theoretically validated. Experimental structures are realized and tested. The model is in agreement with the experimental results. A dimensionless model is proposed to design hybrid fluid structures for micromachines

System Modeling of a MEMS Vibratory Gyroscope and Integration to Circuit Simulation

Recently, consumer applications have dramatically created the demand for low-cost and compact gyroscopes. Therefore, on the basis of microelectromechanical systems (MEMS) technology, many gyroscopes have been developed and successfully commercialized. A MEMS gyroscope consists of a MEMS device and an electrical circuit for self-oscillation and angular-rate detection. Since the MEMS device and circuit are interactively related, the entire system should be analyzed together to design or test the gyroscope. In this study, a MEMS vibratory gyroscope is analyzed based on the system dynamic modeling; thus, it can be mathematically expressed and integrated into a circuit simulator. A behavioral simulation of the entire system was conducted to prove the self-oscillation and angular-rate detection and to determine the circuit parameters to be optimized. From the simulation, the operating characteristic according to the vacuum pressure and scale factor was obtained, which indicated similar trends compared with those of the experimental results. The simulation method presented in this paper can be generalized to a wide range of MEMS devices111Ysciescopu

Design of Piezoresistive MEMS Accelerometer with Optimized Device Dimension

The advent of microfabrication has given a great impetus to MEMS inertial sensors particularly MEMS automobile sensors. In developing Microsystem technology, FEA has been acknowledged as the most cost and time effective alternative to building a prototype for simulation. Present work focuses on developing mathematical model in order to formulate a design procedure to determine the influence of geometric attributes of a four and an eight beam cross bridged accelerometer for automotive applications pertaining to lower inertial loads ( 2g). The configuration is so chosen to minimize cross-axis sensitivity and temperature variation. The proposed mathematical model takes both mechanical and electrical aspects into consideration. Both accelerometers are doped with p-type (boron diffused) silicon at two ends of its flexures. An optimization based on genetic algorithm has been carried out to determine the best possible geometric configuration while satisfying the specification of automotive inertia sensors. A solid model based on optimized dimensions has been simulated using ANSYS to determine stress, deformation, sensitivity for both configurations followed by validation with analytical results. The two configurations have been compared on the basis of output behaviour and performance parameters, and the obtained results are described in detail

Learning from Crickets: Artificial Hair-Sensor Array Developments

We have successfully developed biomimetic flowsensitive hair-sensor arrays taking inspiration from mechanosensory hairs of crickets. Our current generation of sensors achieves sub mm/s threshold air-flow sensitivity for single hairs operating in a bandwidth of a few hundred Hz and is the result of a few iterations in which the natural system (i.e. crickets filiform hair based mechano-sensors) have shown ample guidance to optimization. Important clues with respect to mechanical design, aerodynamics, viscous coupling effects and canopy based signal processing have been used during the course of our research. It is only by consideration of all these effects that we now may start thinking of systems performing a “flow-camera” function as found in nature in a variety of species

Steady-state and transient analysis of electro-thermal microactuators using finite element methods

Recent techniques in radar and communication systems favor the development of phased arrays. The major problems to such systems are size and cost due to the large number of individual transmit/receive modules required. Photonic systems implemented in MEMS technology have reduced bulk optical systems to microscale proportions. This reduction in scale is particularly important to phased arrays since it allows flexibility in deployment. This thesis aims to understand the steady state and transient characteristics of an electrically heated, thermally driven, surface micromachined MEMS polysilicon beam flexure actuator to be employed for the rotation of an r-f phase shifter utilized in phased array systems. The characteristics of the thermal actuator are examined through finite element analysis by investigating the relative importance of the temperature dependencies of the material properties of MUMPs polysilicon. The comprehensive finite element model of the thermal actuator developed using ANSYS 5.6, a commercial finite element package, has the ability to include full temperature dependencies of all parameters and also has the capacity to impose all heat transfer modes, which are beyond the capabilities of current analytical models. Steady-state thermal profiles of the thermal actuator are presented for the thermal actuator in an environment of air and vacuum. The model is validated indirectly by comparing the steady-state deflections with measured data of six thermal actuators of different geometries. The finite element simulations are also validated with a previous analytical model to compare model accuracy. The dynamic behavior of the thermal actuator is examined in both air and vacuum, which gives an insight into power and energy consumption of the thermal actuator. Initial results show a limited power and energy savings for the thermal actuator operated in vacuum over that operated in air. Design optimization of the thermal actuator is investigated using the ANSYS Parametric Design Language (APDL) with the Subproblem Approximation Method for maintaining low power consumption. An indirect method is employed by maximizing the steady-state deflection for unloaded actuators and minimizing the steady-state deflection for loaded actuators for the same applied voltage. A significant reduction in power consumption with an increase in the maximum steady-state deflection has been observed for unloaded actuators. For loaded actuators the available force output is increased slightly, the steady-state deflection decreased slightly and the power consumption increased slightly

Micro-Resonators: The Quest for Superior Performance

Microelectromechanical resonators are no longer solely a subject of research in university and government labs; they have found a variety of applications at industrial scale, where their market is predicted to grow steadily. Nevertheless, many barriers to enhance their performance and further spread their application remain to be overcome. In this Special Issue, we will focus our attention to some of the persistent challenges of micro-/nano-resonators such as nonlinearity, temperature stability, acceleration sensitivity, limits of quality factor, and failure modes that require a more in-depth understanding of the physics of vibration at small scale. The goal is to seek innovative solutions that take advantage of unique material properties and original designs to push the performance of micro-resonators beyond what is conventionally achievable. Contributions from academia discussing less-known characteristics of micro-resonators and from industry depicting the challenges of large-scale implementation of resonators are encouraged with the hopes of further stimulating the growth of this field, which is rich with fascinating physics and challenging problems

Analysis Of The Suspension Beam In Accelerometer For Stiffness Constant And Resonant Frequency By Using Analytical And Numerical Investigation

Mikro-meterpecut yang digunakan dalam pelbagai penerapan hanya akan tercapai dengan jayanya sekiranya keperluan frekuensi resonans dan kepekaan dapat dipenuhi dan konsisten. A successful and consistent performance of micro-accelerometer which has been applied in various applications can only be achieved when the resonant frequency and the sensitivity requirement are fulfilled

Analysis Of The Suspension Beam In Accelerometer For Stiffness Constant And Resonant Frequency By Using Analytical And Numerical Investigation [TL589.2.A3 W872 2007 f rb].

Mikro-meterpecut yang digunakan dalam pelbagai penerapan hanya akan tercapai dengan jayanya sekiranya keperluan frekuensi resonans dan kepekaan dapat dipenuhi dan konsisten. Berdasarkan syarat-syarat tersebut, analisis struktur pada pekali kekukuhan and frekuensi resonans bagi rasuk ampaian dalam meter pecut dan seterusnya pengoptimuman kepada kepekaan haruslah dilakukan. A successful and consistent performance of micro-accelerometer which has been applied in various applications can only be achieved when the resonant frequency and the sensitivity requirement are fulfilled. In view of this, structural analysis on stiffness constant and resonant frequency for the suspension beam in accelerometer, and subsequently optimization design of accelerometer with respect to sensitivity in term of displacement against acceleration must be performed

Thermal Characterization and Parametric Optimization of a Thermal Bimorph for use in Mirco-Robotics Applications

The thermal bimorph actuator is a multi-layer Micro-Electro-Mechanical (MEMS) device used to achieve out-of-plane mechanical displacements in response to a thermal input. This device is one of the simplest MEMS devices to manufacture. Previous investigations of thermal bimorph actuators have studied the best materials to use based on ease of deposition, and the overall effect on the devices. The current work presents an optimization of the thermal bimorph (Aluminum and Polysilicon) actuator geometry, for a target application of a micro robotics actuator. The application of bimorph actuators to micro robotics demands high efficiency in the conversion from thermal energy to mechanical displacement, since low efficiencies require larger power supplies and reduce the payload capacity of the the micro-robot. Two subsystems with significant impact on bimorph actuator efficiency include the thermal mass of the substrate (modeled with three parameters) and the relationship between various geometrical dimensions (modeled with four parameters) of the actuator leg. Each subsystem is optimized using a transient finite element analysis of the coupled thermal and mechanical response. Parametric studies were used to investigate the response curve of the target functionals and then optimized using a local steepest descent algorithm. The optimized system results in a nominally 200 % higher payload capacity with 350 % stiffer mechanical characteristics. Results of the investigation demonstrate the need for more accurate material properties at the micro-scale. The mass of the power supply required to achieve sustained micro robot motion using thermal bimorph actuators currently exceeds the corresponding payload capacity of the device