This paper presents a novel, highly sensitive condenser microphone with a flexure hinge diaphragm. We used the finiteelement
analysis (FEA) to evaluate the mechanical and acoustic performance of the condenser microphone with a hinge
diaphragm. And we fabricated the miniature condenser microphones with area of 1.5 mm x 1.5 mm. From the simulation
and measurement results, we confirmed that the maximum displacements at the center of flexure hinge diaphragms are
several hundred times, compared with flat diaphragms. Moreover, the miniature microphones have obtained -3 dB
bandwidth of nearly 20 kHz by proper design of the flexure hinge diaphragms.
The MEMS (micro-electro-mechanical systems) microphone enables the manufacturing of small mechanical
components on the surface of a silicon wafer. The MEMS microphones are less susceptible to vibration because of the
smaller diaphragm mass and an excellent candidate for chip-scale packaging. The PMN-PT materials itself exhibit
extremely high piezoelectric coefficients and other desirable properties for an acoustic sensor. In this paper, we present a
piezoelectric MEMS microphone based on PMN-PT single crystal diaphragm. The fabrication process including dry
etching conditions and scale-factored prototype is presented. In particular, this paper introduces the design of a PMN-PT
single crystal diaphragm with interdigitated electrode.
This paper presents the fabrication process of a novel aperture which allows near field optical data storage. We use
PMN-PT ((1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3) single crystal material - a new generation oxide material known as relaxor
ferroelectrics that exhibits extraordinary piezoelectric properties - to fabricate microlenes using photolithography and dry
etching techniques. In this paper, we describe the fabrication processes of a PMN-PT single crystal material microlens
prototype with a miniature aperture for near field optical data storage. PMN-PT has the merits of transparency for optical
usage and also has a high dielectric coefficient that is suitable for actuator and sensor applications. It provides an
advantage of manufacturing both aperture and actuator/sensor with the same material. The thermal reflow technique is
used to fabricate photoresist microlenses on a freestanding single crystal PMN-PT film as a mask. The PMN-PT lenses
are fabricated by a chemically assisted ion beam etching (CAIBE) technique. Finally the focused ion beam (FIB)
machining process is used to place a miniature aperture at the apex of the microlens. We were able to successfully
fabricate the 10μm PMN-PT microlenses with less than 100nm apertures. From the experimental measurement, we were
able to obtain the optical throughput of 1.83x10-7 from a 50nm aperture.
In this paper, we report an innovative depth-sensing nanoindenter using a lead zirconium titanate (PZT) stack actuator. The conventional nanoindenter requires two sensors and closed-loop controls for precise loading or positioning due to inherent high hysteresis and creep characteristics of the PZT actuators. On the other hand, we have shown that an open-loop positioning control scheme using a single displacement sensor can be used for nanoindentation. The developed control scheme compensates for the hysteresis and creep errors of PZT actuators. By adopting the single-sensor open-loop control, the overall system structure can be simplified and a robust control environment can be achieved. In addition, a high positioning repeatability was achieved by using a flexure type mainframe with a high preload applied to the PZT actuator. To verify the system performance, we conducted the standard indentation tests on a fused quartz sample, and the results were compared with those from a commercial nanoindenter. Besides the basic nanoindentation functions, the developed system also has the capability for surface imaging through a scanning function. The pre-indentation scanning capability proved to be a very useful method for positioning the tip in the desired indentation location. Similarly, post-indentation scanning allows for visualization of the indentation marks after the tests.
The small form factor optical data storage devices are developing rapidly nowadays. Since it is designed for portable and compatibility with flesh memory, its components such as disk, head, focusing actuator, and spindle motor should be assembled within 5 mm. The thickness of focusing actuator is within 2 mm and the total working range is +/-100um, with the resolution of less than 1μm. Since the thickness is limited tightly, it is hard to place the yoke that closes the magnetic circuit and hard to make strong flux density without yoke. Therefore, Halbach array is adopted to increase the magnetic flux of one side without yoke. The proposed Halbach array type focusing actuator has the advantage of thin actuation structure with sacrificing less flex density than conventional magnetic array.
The optical head unit is moved on the swing arm type tracking actuator. Focusing coil is attached to swing arm, and Halbach magnet array is positioned at the bottom of deck along the tracking line, and focusing actuator exerts force by the Fleming's left hand rule. The dynamics, working range, control resolution of focusing actuator are analyzed and performed.
In this paper, novel piezoelectric microbalance biosensors using single crystal lead zinc niobate-lead titanate (PZN-PT) and lead magnesium niobate-lead titanate (PMN-PT) are presented. The PZN-PT/ PMN-PT materials exhibit extremely high piezoelectric coefficients and other desirable properties for biosensors, supposed to be a superior substitution for the conventional quartz crystal with the improved performance. . These biosensors provide rapid and minute quantitative target detection by monitoring the change in resonance frequency of the crystal probe. With the geometrical variations, various prototypes are compared with conventional quartz crystal microbalances (QCM). The superiority of the materials over conventional quartz crystal is demonstrated experimentally in terms of sensitivity. In addition, we examine the feasibility of ultra miniaturization of the PZN-PT based biosensor by fabricating freestanding single crystal films of the PZN-PT and patterning micro-scale biosensors with ion milling and argon-ion laser-induced etching technique. A fabricated prototype sensor utilizing the material in a thin film form has a size of 300x100x7um3.
A smart cantilever structure using single-crystal relaxor ferroelectric material is presented. The smart cantilever possesses both sensing and actuation capabilities, embedded in a monomorph and resulting in a smart structure. Single crystal relaxor ferroelectric materials (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) and (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) are ideal for actuator and sensor applications since they exhibit very high piezoelectric coefficients. We separately pattern interdigitated electrodes on the top and bottom surfaces of a single crystal cantilever beam. The interdigitated electrode design results in an electric field- gradient that after poling not only induces flapping actuation but also, simultaneously, allows us to detect internally or externally induced stresses. As a monolithic actuator integrated with a sensor, it has potential applications in various Micro-Electro-Mechanical Systems (MEMS), Scanning Probe Microscopy (SPM) and Near-field Scanning Optical Microscopy (NSOM). We fabricate monomorph prototypes and characterize their performance in terms of actuation displacement and sensing capabilities, respectively. Finally, an active vibration control experiment was successfully conducted by using the smart cantilever structure.
A novel design of an atomic force microscope (AFM) with a (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystal scanner and a self-sensing cantilever is presented in this paper. The piezoelectric scanner and the self-sensing cantilever are integrated into a small-sized all-in-one structure with a microscope objective focused on the tip. The Z-scanner consists of two parallel PMN-PT unimorphs. This design can minimize the rotation and the sideways deflection at the sensing tip. The XY-scanner consists of two perpendicular small rods of PMN-PT. In this design, each PMN-PT rod serves as an actuator as well as a flexure because of the elastic property of the single crystal material. Under this configuration, the XY scanner can guarantee a fully decoupled planar scanning motion without positioning sensors and a sophisticated closed-loop control mechanism which is required for a XY scanner with conventional piezoelectric tubes. Furthermore, by adopting a self-sensing MEMS cantilever, the AFM design is simplified by discarding various optical sensing components. The attached objective offers fast visible inspection and rough positioning of the tip for measurement setups. We used a digital signal processor (DSP) based control scheme to achieve fast control speeds of the AFM. We also used LABVIEW for a flexible programming environment. We conducted finite-element analyses to characterize the dynamic performance of the AFM system. The system showed a high frequency band due to the small inertia of the moving part with relatively rigid structure. In addition, various scanning tests were performed to demonstrate that the system is capable of providing near video images.
In this paper, a small size monolithic XY scanner was designed and fabricated. The scanner has a flat triangular shape and consists of two 0.5mm-thick and 5mm-long lead-zinc-niobate-lead-titanate ((1x)Pb(ZnNb)O3 - xPbTiO3) or PZN-PT rods. The use of this material is critical to the reduction of the scanner size. The mechanical resonance characteristics for the PZN-PT rods and the assembled scanner were tested. The fabricated scanner provides a high resonance frequency and assured parallelism between the scanner and the sample surface. It enables a fast open loop control capability that naturally lends itself to use in scanning probe microscopy. The scanner and a self-sensing cantilever were integrated into a small-size atomic force microscope (AFM) design. A commercially available self-sensing cantilever and an additional actuator were used for contact scanning of a HOPG (Highly Ordered Pyrolytic Graphite) sample surface. The scanning performance of the scanner was verified by obtaining atomically resolved image of the HOPG surface.
Near-field optical storage using cantilever aperture tip is a promising way for next generation optical data storage. To enhance the speed of reading and writing data, gap between tip and media should be controlled fast and precisely within near field region. In this paper, several PZT actuators are analyzed for constructing dual servo control algorithm: coarse actuators (stack PZT, bimorph PZT) for media surface inclination and fine actuator (film PZT) for media surface roughness. Dynamic analysis of stack PZT, bimorph PZT, and film PZT are performed through the frequency response. Based on the frequency response and mathematical model, fast analog controller is designed and experimented. From experimental results, analog control of film PZT is 50 times faster than conventional stage. We get the 0.1 msec over 800nm step.