Masaya Takasaki

Bio: Masaya Takasaki is an academic researcher from Saitama University. The author has contributed to research in topics: Electromagnetic suspension & Vibration isolation. The author has an hindex of 16, co-authored 215 publications receiving 1218 citations.

Surface acoustic wave tactile display

Abstract: Developing realistic tactile displays for virtual reality has been challenging. Tangible displays are increasingly important interfaces not only for augmenting the reality of computer graphics but also for conveying graphical information to persons with visual impairments. We propose a tactile display using surface a acoustic waves. We can continuously change the fineness of the surface's grain by controlling the SAWs' burst frequency.

Vibration Isolation System Using Negative Stiffness

Abstract: A new vibration isolation system using negative stiffness realized by active control technique is proposed in this paper. The serial connection of a normal spring and a suspension system with negative stiffness enables the isolation system to have low stiffness for vibration from the ground and high (theoretically infinite) stiffness against direct disturbance acting on the isolation table. A control method of realizing negative stiffness with a linear actuator is presented in an analytical form. The validity of this method is confirmed experimentally with an apparatus equipped with a voice coil motor. It is also confirmed experimentally that high stiffness against direct disturbance on the isolation table can be achieved in the proposed vibration isolation system.

Development of a three-axis active vibration isolator using zero-power control

Abstract: This paper presents the development of an active 3-degree-of-freedom (DoF) vibration isolation system using zero-power magnetic suspension. The developed system is capable to suppress direct disturbances and isolate ground vibrations of the 3-DoF motions, associated with vertical translational and rotational modes. Two categories of control strategy for the actuators are proposed, i.e., local control and mode control. The latter method allows to overcome limitations of the poor performances for rotational modes exhibited by the former. A mathematical model of the system is derived and each DoF motion is treated separately for the control system. It is demonstrated analytically that the infinite stiffness to static direct disturbances can be generated and the resonance peak due to floor vibration can effectively be suppressed for the system. Moreover, the experiments have been carried out to measure the static and dynamic responses of the isolation table to direct disturbances, and transmissibility characteristic of the isolator from the floor. The results indicate good vibration isolation and attenuation performances, and show the efficacy of the developed isolator for industrialization

A device for fabricating protein chips by using a surface acoustic wave atomizer and electrostatic deposition

Abstract: We propose a new advanced fabrication method for protein chips using a surface acoustic wave atomizer and electrostatic deposition, named SAW-ED. A SAW atomizer is utilized in order to spray extremely small droplets, while the electrostatic force and shadow mask are used for collecting the charged particles onto the deposition substrate with the designed pattern. To estimate the quality of SAW-ED, we performed experiments concerning particle-size uniformity, the shapes of protein deposition, protein bioactivity, deposition rate, fluorescent uniformity, spot-size uniformity and collection efficiency. Protein deposition of BSA was formed in a completely dry state and particle diameter ranged from 0.05 to 0.7 μm. By utilizing an insulator mask, protein patterns with complex shapes were formed with relatively uniform thickness distribution. The deposition of luciferase was conducted and bioluminescence showed its activity was preserved. The chips of multi anti-IgG antibodies were also formed and their specific bioactivity as an immunoglobulin was verified by luminescence immunoassay. The detecting sensitivity reached as low as 1 ng/ml mouse IgG by fluorescence immunoassay. Deposition rate is linear to atomization time. Coefficient of variation in the fluorescence and the mean diameter of SAW-ED spots are 0.0356 and 0.0361 respectively. By using a collimating electrode, the collection efficiency increased up to 33.3%.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Abstract: This article reviews acoustic microfiuidics: the use of acoustic fields, principally ultrasonics, for application in microfiuidics. Although acoustics is a classical field, its promising, and indeed perplexing, capabilities in powerfully manipulating both fluids and particles within those fluids on the microscale to nanoscale has revived interest in it. The bewildering state of the literature and ample jargon from decades of research is reorganized and presented in the context of models derived from first principles. This hopefully will make the area accessible for researchers with experience in materials science, fluid mechanics, or dynamics. The abundance of interesting phenomena arising from nonlinear interactions in ultrasound that easily appear at these small scales is considered, especially in surface acoustic wave devices that are simple to fabricate with planar lithography techniques common in microfluidics, along with the many applications in microfluidics and nanofluidics that appear through the literature.

Surface Acoustic Wave Microfluidics

Abstract: Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10–1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena—from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization—underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

Bio-microarray fabrication techniques--a review.

Abstract: Microarrays with biomolecules (e.g., DNA and proteins), cells, and tissues immobilized on solid substrates are important tools for biological research, including genomics, proteomics, and cell analysis. In this paper, the current state of microarray fabrication is reviewed. According to spot formation techniques, methods are categorized as "contact printing" and "non-contact printing." Contact printing is a widely used technology, comprising methods such as contact pin printing and microstamping. These methods have many advantages, including reproducibility of printed spots and facile maintenance, as well as drawbacks, including low-throughput fabrication of arrays. Non-contact printing techniques are newer and more varied, comprising photochemistry-based methods, laser writing, electrospray deposition, and inkjet technologies. These technologies emerged from other applications and have the potential to increase microarray fabrication throughput; however, there are several challenges in applying them to microarray fabrication, including interference from satellite drops and biomolecule denaturization.

Haptic device with indirect haptic feedback

Abstract: A haptic device provides indirect haptic feedback and virtual texture sensations to a user by modulation of friction of a touch surface of the device in response to one or more sensed parameters and/or time. The sensed parameters can include, but are not limited to, sensed position of the user's finger, derivatives of sensed finger position such as velocity and/or acceleration, sensed finger pressure, and/or sensed direction of motion of the finger. The touch surface is adapted to be touched by a user's bare finger, thumb or other appendage and/or by an instrument such as a stylus held by the user.