Fig 6 - uploaded by Shekhar Bhansali
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(a) Schematic of the sensor plate fabrication process: (A) Clean wafer and deposit electroplating seed layer. (B) Spin and expose photoresist. (C) Develop photoresist and electroplate. (D) Strip resist and etch seed layer. (E) Spin polyimide, spin, and expose resist. (F) Develop resist, etch polyimide, strip resist, and cure polyimide (to get tapered sidewalls). (G) Deposit seed layer, spin, expose, and develop resist. (H) Electroplate via and interconnect, strip resist, and etch seed layer. (b) Photograph of the electroplated sensor coil with planar interconnect.
Source publication
We have successfully developed a one degree-of-freedom
microsuspension system, with active position control, as a paradigm of a
micromagnetic bearing. This system integrates an electromagnetic
actuator, a position sensor, and a feedback control system that provides
active position control. This paper discusses the design and fabrication
details of...
Contexts in source publication
Context 1
... as potential substrate material for the sensor coils. Si was preferred to glass as the substrate for the sensor coils because of its higher thermal conductivity. Higher thermal conductivity of the substrate resulted in better heat dissipation from the coils and improved performance (be- cause of lower temperature-related impedance drifts). Fig. 6(a) schematically illustrates the sensor coil plating process. The sensor coils are plated on a separate Si wafer. After the depo- sition of the seed layer, photoresist was spun on the wafer and patterned. The sensor coils were then electroplated using the gold electroplating process. A thieving ring was incorporated around the coils, in ...
Context 2
... fabricate planar interconnects, the coils were planarized with Hitachi PIX 3400, an insulating polyimide. The polyimide was patterned to open the vias and bonding pads. A seed layer was deposited, patterned, and electroplated to fabricate the planar interconnects and complete the electrical circuit. Fig. 6(b) is the photograph of one of the sensor coils with planar interconnects. The array of sensor coils is diced in pairs and for assembly. The metallic lines around the set of coils in Fig. 7 are the electroplated thieving rings. The spacers are made of borosilicate glass. The spacers are diced from a substrate that has been thinned to ...
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Citations
... Scientific Community, in the MEMS domain, is busily working on two main fronts. The first one, purely theoretical, is heavily involved in modeling of coupled problems including the coupled thermal-elastic systems [2,3], the modeling of magnetically actuated systems [4,5], the microfluidics devices [6][7][8] and the modeling of electric-elastic systems [9][10][11]. The second one, in practice, mainly deals with the MEMS technology transfer operational techniques in different areas pushing up to the modern Bio-MEMS for biomedical engineering, such as miniaturized bio-sensors and their application to diagnostics and tissue engineering [12,13]. ...
In this paper we present, in a framework of 1D-membrane Micro-Electro-Mechanical- Systems (MEMS) theory, a formalization of the problem of existence and uniqueness of a solution related to the membrane deformation u for electrostatic actuation in the steady- state case. In particular, we propose a new model in which the electric field magnitude E is proportional to the curvature of the membrane and, for it, we obtain results of existence by Schauder-Tychono's fixed point application and subsequently we establish conditions of uniqueness. Finally, some numerical tests have been carried out to further support the analytical results.
... For devices operating in vacuum conditions, any damage to the container might result in a loss of vacuum and consequently change the viscosity. In any of these cases, asymmetries affect the behavioral changes and unwanted deviations from the desired output, which can be modeled with mathematical expressions [2][3][4][5][6][7][8][9][10]15,[26][27][28]. ...
Multiple-model adaptive estimation techniques have been previously successfully applied to fault diagnosis of microsystems. Their diagnosis performance highly depends on the accuracy of modeling techniques used in representing faults. This paper presents the application of a self-tuning forgetting factor technique in the modeling of faults in MEMS and its effects on diagnosis performance compared with the application of Kalman filters and fixed gain estimation techniques. The self-tuning-based modeling used in the diagnosis algorithm was experimentally implemented. It demonstrated superior results compared to Kalman filter and fixed gain estimation techniques by accelerating the diagnosis process.
... Closed-loop feedback control of dynamic systems is useful in improving system performance and reliability. Researchers have applied feedback control to MEMS devices [1]- [10], but one of the major challenges to the effective application of closed-loop control to MEMS is the feedback sensor. It is difficult to monitor the performance of many MEMS devices due to their micro-scale size. ...
Feedback control of microelectromechanical systems (MEMS) devices has the potential to significantly improve device performance and reliability. One of the main obstacles to its broader use is the small number of on-chip sensing options that are available to MEMS designers. A method of using integrated piezoresistive sensing is proposed and demonstrated as another option. Integrated piezoresistive sensing utilizes the inherent piezoresistive property of polycrystalline silicon from which many MEMS devices are fabricated. As compliant MEMS structures flex to perform their functions, their resistance changes. That resistance change can be used to transduce the structures' deflection into an electrical signal. The piezoresistive microdisplacement transducer (PMT) is a demonstration structure that uses integrated piezoresistive sensing to monitor the output displacement of a thermomechanical inplane microactuator (TIM). Using the PMT as a feedback sensor for closed-loop control of the TIM provided excellent tracking with no evident steady-state error, maintained the positioning resolution to plusmn29 nm or less, and increased the robustness of the system such that it was insensitive to significant damage.
... Closed-loop control is able to overcome these problems and many linear approaches have been tried. For examples, PD-type controllers were developed in [4,5] to control a 1 DOF magnetically-levitated micro-suspension system and an elec-trostatic actuated MEM optical switch, the advantages and disadvantages of simple open-loop and closed-loop control strategies for electrostatic comb actuators with bi-directional drive were studied in [6], respectively. In recent years, different nonlinear control techniques have been extended to the control of electrostatic micro-actuator. ...
... Besides, the following assumptions are made for system (4 ...
... where Theorem 1. For the nonlinear electrostatic micro-actuator system with the external disturbances and the uncertain parameters described by (4), when the robust adaptive dynamic surface control law (20) and the parameter adaptive law (15) are applied to the tracking control, the output tacking error e 1 satisfies the H 1 tracking performance if any positive constant d for any initial condition satisfies V < d. ...
A novel adaptive robust tracking control scheme is proposed for a class of single-degree-of-freedom (1DOF) electrostatic micro-actuator systems in the presence of parasitics, parameter uncertainties and external disturbances. This method integrates the adaptive dynamic surface control and H-infinity control techniques. Based on this method, both the design procedure and the derived tracking controller itself are simplified, and the controller guarantees that the output tracking error satisfies the H-infinity tracking performance. In addition, the tracking accuracy can be adjusted by an appropriate choice of the design parameters of the controller. Simulation results show that prescribed transient output tracking performance can be achieved, and the closed-loop system exhibits good robustness to system uncertainties.
... However, the electrostatic actuator is not an option for driving a microamplification device that is considered in this article due to its low output force. The electromagnetic (Fulin et al., 1998;Bhansali et al., 2000), piezoelectric (Xu et al., 2002;Tagawa et al., 2003), and thermal actuation (Sinclair, 2000;Que et al., 2001;Chu et al., 2003) have enough force generation capabilities for the microscale device that is presented in this article. However, it is a very challenging task to make a threedimensional shape of electrical conducting coils in MEMS scale, which is related directly to the performance of electromagnetic actuator. ...
This article proposes the design of several microelectromechanical amplification devices formed of many identical microunits that are connected in a serial–parallel configuration, each being individually actuated and amplifying its own input motion. The microdevices realize the border-crossing from the micro-to the meso-scale displacement domain as they combine the micron-level individual inputs into millimeter-range output levels. The base structural unit is a flexure-based compliant device that is capable of transforming the input from a thermal actuator into an amplified displacement, about a direction perpendicular to the input one. The base unit is designed based on performance criteria, such as displacement amplification, input stiffness and output stiffness by utilizing finite element simulation, and an algorithm based on closed-form compliance equations of the incorporated flexure hinges. The microelectromechanical amplification device is monitored by means of embedded capacitive displacement sensors for the input port. The feasibility of the device design was verified through a numerical simulation and some initial experimental results are presented.
... PICTURE 10. CROSS-SECTIONAL OF THE SILICON PLATFORM PLATE [14] The coefficient of dynamic friction between the small smooth surfaces of the micromachined components has been estimated to be 0.2 to 0.5. Magnetically suspended levitated noncontact devices are highly desirable for active MEMS components. ...
... The paper [14] describes MEMS component of the microsuspension system. The drive coil is electroplated around a highly compliant beammass structure, which is designed to allow large deflections along the vertical direction and to constrain movement in all other directions. ...
The design of sensors and RF components has increasingly made use of microelectromechanical systems (MEMS) technology or micromachining. The quality-factor of inductors on silicon and the reduction of substrate losses requires approaches as the use of MEMS technology. The MEMS technology had emerged from the conventional silicon processes with the aim to utilize the well-established microstructuring technology but to exploit the excellent mechanical rather than the electrical characteristics of silicon. Passive components, especially inductors, used often determine the size and performance of systems and current research efforts in MEMS aimed at performing these functions mechanically should make it possible to realize the entire transducer and RF transcever monolithic ally, reducing size, weight, cost and power.
... The key of sensorless control is the impedance analysis during operation. Typical measurement circuits for eddy current sensor evaluation such as relaxation oscillators [2] or bridge circuits [5] can not be used. In [6] the impedance of the coil is calculated by short positive and negative voltage impulses and the current response. ...
Sensorless control means for a gripper based on a solenoid actuator are discussed in order to reduce the number of components in an autonomous mobile robot. As the information of the armature position is found in the solenoid's impedance, a method based on the current difference between start and end of a pulse width modulated impulse is introduced and evaluated by experiments. The controller is implemented in three phases, starting with the closing of the gripper in position control, the transportation phase with a fixed retention force in force control and ending in the opening phase of the gripper.
The paper focuses on motion control of a planar MEMS manipulator with three kinematic Degrees-Of-Freedom. The manipulator measures approximately 1.6 mm across and the size of its work envelope is approximately 20 μm across. It is suspended 2 μm above the substrate. The device is powered by three sets of thermal motors. The kinematic mobility of the mechanism is provided by more than 75 flexures connecting its rigid components. The objective of the study is to control the motion of the manipulator using commercially available general purpose laboratory software and hardware using only visual feedback. The application of a rigid-link kinematic model of the compliant manipulator structure proved to be practical. The general purpose imaging software was the slowest component of the feedback resulting in about 1s intervals between the control steps. The measured path tracing errors of 0.3 μm were close to the imagine apparatus resolution of 0.3μm / pixel.
Fault in MEMS can originate from local defects, parameter tolerances, design problems, operation, and/or system-level defects. For instance, a fault might happen because of a fracture in different parts of the device, such as suspension springs or fingers. In open-to-air applications, there is a chance that dust and other particles fall on the structure of the device, which may cause a sudden mass change. In addition, the silicon-made structures absorb humidity from air, which results in changes in the mechanical properties of the suspension springs. For devices operating in vacuum conditions, any damage to the container might result in a loss of vacuum and, consequently, change in viscosity. In any of these cases, asymmetries result in behavioral changes and unwanted deviations from the desired output, which can be modeled in mathematical expressions. In this chapter, the origins of fault are discussed, related mathematical models are obtained, and Kalman filters are developed and utilized in fault diagnosis. The structure of a multiplemodel adaptive estimator is illustrated, and its application in fault diagnosis is simulated and experimentally verified. Other model-based diagnosis techniques wherein model parameters are identified and updated automatically are introduced, and their fault diagnosis performances are compared.
The ability to supply power at the micro level from the ambient energy is an increasingly important area of MEMS. This paper presents a methodology for the design of an electromagnetic micro generator that converts mechanical energy associated with the low amplitude vibration present in structures such us tall buildings and bridges to electrical power. The generator consists of a rigid housing and a moving magnet suspended on a flat spring that induces a voltage on a stationary coil attached to the housing. Finite Element Analysis (FEA) software (ANSYS5.7) has been used to analyse different designs of flat springs and to select one that is capable of large deflection. The effects of the main design parameters: length, width, thickness and material properties on the spring deflection were modelled. Maximum static deflection of 13.43mum is achieved under the gravitational force. Furthermore, Free vibration characteristics of the suspended magnet are also presented. Maximum electric power of 14.5nW is calculated for the spring with natural frequency of 18.56 Hz when the input vibration frequency and its amplitude are assumed to be 3kHz and 5mum. An outline of how the design can proceed in a logical manner is discussed.
