Masanori Ueda

Nanospheres for DNA separation chips

We report here a technology to carry out separations of a wide range of DNA fragments with high speed and high resolution. The approach uses a nanoparticle medium, core-shell type nanospheres, in conjunction with a pressurization technique during microchip electrophoresis. DNA fragments up to 15 kilobase pairs (kbp) were successfully analyzed within 100 s without observing any saturation in migration rates. DNA fragments migrate in the medium while maintaining their characteristic molecular structure. To guarantee effective DNA loading and electrofocusing in the nanosphere solution, we developed a double pressurization technique. Optimal pressure conditions and concentrations of packed nanospheres are critical to achieve improved DNA separations.

Development of Piezoelectric Thin Film Resonator and Its Impact on Future Wireless Communication Systems

The bulk acoustic wave filter composed of piezoelectric thin film resonators has many features superior to those of other small filters such as a surface acoustic wave (SAW) filter and a ceramic filter. As it has no fine structure in its electrode design, it has a high Q factor that leads to low-loss and sharp-cut off characteristics and a high power durability particularly in the high-frequency range. Furthermore, it has the potentiality of integrated devices on a Si substrate. In this paper, we review the recent developments of piezoelectric thin film resonator filters in the world, including our development for mobile communication applications. After describing the feature and history of the piezoelectric thin film resonator filters, our technologies are introduced in focusing on the resonator structures, the piezoelectric thin film and electrode film materials, the cavity structures, the filter structure and its design rules and characteristics, comparing with SAW filters. The competition and coexistence between the piezoelectric thin film resonator filters and the SAW filters are also described. In this paper, we describe the development of a piezoelectric thin film resonator from the standpoint of researchers who have a long experience of SAW filter development.

ELECTROPHORESIS OF LONG DNA MOLECULES IN LINEAR POLYACRYLAMIDE SOLUTIONS

Electrophoresis of long DNA (T4 DNA; 166 kb, S. pombe chromosomal DNA; 3-6 Mb) in linear polyacrylamide solutions was investigated by fluorescence microscopy and capillary electrophoresis. In the past studies on electrophoresis of long DNA in a polymer solution, it was reported that DNA migrates in U-shape conformation. We found that at higher polymer concentrations, the shape of the migrating DNA changes from U shape to linear shape (I-shape conformation). In the migration mode with the I-shape conformation, the DNA moves with almost constant velocity and constant shape. However, the migration velocity does depend on the DNA size, and it is possible to separate DNAs under this I-shape motion. Actually, Mb-sized DNAs are well separated within 5 min in the region for the I-shape motion by means of capillary electrophoresis with a DC field. Considering that it takes 20 h to separate Mb-sized DNAs by standard pulsed-field gel electrophoresis (PFGE), this results will be useful for the separation of giant DNAs.

Correlation between temperature coefficient of elasticity and fourier transform infrared spectra of silicon dioxide films for surface acoustic wave devices

We investigated the correlation between the temperature coefficient of elasticity (TCE) and Fourier transform infrared (FT-IR) absorption spectra of SiO2 for SAW devices. The measurement indicated that the TCE is strongly correlated with peak frequencies; that is, with the fractional change of the Si-O-Si bond angle with temperature.

Low-Loss Piezoelectric Transformer Using Energy Trapping of Width Vibration

Piezoelectric transformers proposed by Rosen have been studied for high-voltage step-up applications. A piezoelectric transformer using LiNbO3 proposed recently by Nakamura and Adachi has low loss and a simple structure. The plate of a conventional piezoelectric transformer was supported only at the node of vibration. Rigid support and loss suppression are required for high-power and high-voltage applications. To apply a piezo-electric transformer to a power circuit, we studied methods for supporting the piezoelectric plate and reducing loss. Based on these studies, we proposed a piezoelectric transformer using energy trapping of the width-shear vibration in a LiNbO3 plate.

Investigation of Internal Loss and Power Transmission Characteristic of Width Shear Vibration Piezoelectric Transformer

Piezoelectric transformers proposed by Rosen [ Proc. Electronic Components Symp. (1957) p. 205] have been studied for high-voltage step-up applications. A piezoelectric transformer using a LiNbO3 plate proposed recently by Nakamura et al. [ Proc. Japan Acoustic Society (1990) p. 687 [in Japanese]] has low loss and a simple structure. The plate of a conventional piezoelectric transformer was supported only at the point of the node of the vibration. Rigid support is required for high-power applications. To apply a piezoelectric transformer to a power circuit, we studied internal loss of transmitting power and how to support the piezoelectric plate. Based on the studies, we proposed a piezoelectric transformer which uses energy trapping of width shear vibration in a LiNbO3 plate. This paper describes the investigation of the spurious mode, internal loss and power transmission characteristic. Efficiency of 95% or more can be obtained above a load rasistance range of about 20 Ω and under about 1000 Ω.

Film Bulk Acoustic Resonator using High-Acoustic-Impedance Electrodes

A bulk acoustic wave filter composed of piezoelectric thin-film resonators has many features superior to those of other small filters such as a surface acoustic wave (SAW) filter and a ceramic filter. A high-Q factor and low loss are big advantages for a film bulk acoustic resonator (FBAR). The electrode material that is selected is very important for maintaining a high-Q and appropriate coupling factor. An analysis of the effects of acoustic impedance on AlN-based FBAR performance is described. The electromechanical coupling factor (k2) and filter loss were found to be influenced by acoustic impedance and to be mainly dominated by Youngs modulus. Ru was found by analysis and experiments to be a suitable material for the electrode. Finally, a 2 GHz wide band code division multiple access (WCDMA) filter was demonstrated to have a good performance.

Highly enhanced piezoelectric property of co-doped AlN

We propose a series of new compositions of AlN-based piezoelectric material based on the results of first-principles calculation. The composition is expressed by Al1−xN, where the elements α and β are selected to maintain the charge neutrality of the host AlN. We found that the selection of Mg2+ for α and Hf4+ and Zr4+ for β with y = 0.5 show good chemical stability with much better piezoelectric properties than pure AlN. Our results indicate broad compositional freedom for improving the piezoelectric properties of AlN by using the co-doping technique.

Super-High-Frequency Band Filters Configured with Air-Gap-Type Thin-Film Bulk Acoustic Resonators

The first 24 and 30 GHz band thin-film bulk acoustic resonator (FBAR) filters are reported in this paper. The filters were configured with air-gap-type FBARs on a flat silicon substrate. They were designed using a Butterworth–Van-Dyke (BVD) equivalent circuit considering the linear relationship between resonant frequency, capacitance ratio, and loss in the FBAR. The measured characteristics corresponded with those of the simulation using the equivalent circuit in the pass-band. The center frequency, fractional bandwidth, minimum insertion loss, and out-of-band suppression were 23.8 GHz, 3.4%, -3.8 dB, and -13 dB in the 24 GHz band filter, and 29.2 GHz, 3.4%, -3.8 dB, and -11 dB in the 30 GHz band filter, respectively.

Nonlinear Distortion of Acoustic Devices for Radio-Frequency Front-End Circuit and Its Suppression

In this paper, we discuss the nonlinear performance difference between surface acoustic wave (SAW) and bulk acoustic wave (BAW) resonators, which include intermodulation distortion (IMD) or triple-beat (TB) products, and indicate the importance of reducing even-order nonlinearities of BAW resonators. We were able to validate the accuracy and efficiency of our proposed simulation technique for BAW devices by comparing the results of our simulation with experimental data. We verified that our circuit model is a high-performance tool that can be used to predict BAW device nonlinearities, and we propose how to suppress even-order nonlinearities by employing a thin-film bulk acoustic resonator (FBAR) duplexer for wideband code division multiple access (WCDMA) band 1. Finally, we introduce highly linear FBAR duplexers.