Semicylindrical Acoustic Transducer from a Dielectric Elastomer Film with Compliant
Electrodes
Journal of the Acoustical Society of America, vol.130, no.2, 2011, p.744-752
Takehiro Sugimoto, Kazuho Ono, Akio Ando, Yuichi Morita*, Kosuke Hosoda*, and Daisaku Ishii*
* Foster Electric Co., Ltd.
A
semicylindrical acoustic transducer was constructed using a dielectric elastomer film with
compliant electrodes that is an electroactive polymer composed of a polyurethane elastomer base and polyethylene dioxythiophene/polystyrene sulfonate electrodes. The use of
this dielectric elastomer is advantageous because polyurethane is a common material that keeps its
shape without any rigid frame. Because the dielectric elastomer films are essentially incompressible, electric-field-induced thickness changes are usually translated into much larger changes of
the film area and side length. Here it is proposed that this change in side length can be utilized for
sound generation when the film is bent into a semicylindrical shape. Accordingly, a semicylindrical acoustic transducer was fabricated using a film of thickness of 300 μm and its acoustic characteristics were investigated. The transducer can be operated at low applied voltages by reducing the
film thickness, as long as the film is thick enough to generate sufficient force to overcome sound
radiation impedance. The second harmonic distortion of the transducer was also investigated as
a function of the ratio of the direct current bias voltage to the alternating current audio signal
amplitude.
Spin Transfer Switching of Current-perpendicular-to-plane Giant Magnetoresistance
Devices with Gd-Fe Free Layers and Ag-spacer Materials for Light Modulator Applications
Journal of Applied Physics, vol.109, no.7 pt.3, 07C917, 2011, p.07C917.1-07C917.3
K. Aoshima, Y. Ohtsuka*, Y. Hashimoto, N. Funabashi, K. Machida, K. Kuga, H. Kikuchi, and N. Shimidzu
* Tokai University
W
e investigated how the magneto-optical (MO) and magnetic properties of Gd-Fe-based
giant magneto resistance (GMR) films with silver (Ag) spacers are affected using two
different free-layer compositions, Gd21.7Fe78.3 and Gd27.5Fe72.5 (at. %). GMR films using Ag
spacers exhibited a MO Kerr rotation (θK) that was about 10% larger than that with copper (Cu)
spacers. Moreover, GMRs with Gd21.7Fe78.3 free layers exhibited larger θK and saturation magnetization (Ms) values than did those with Gd27.5Fe72.5 free layers. Current-perpendicular-to-plane (CPP)
GMR devices using Gd21.7Fe78.3 and Gd27.5Fe72.5 free layers with Ag spacers were fabricated and
employed in order to investigate the device’s spin transfer switching characteristics. The switching
current density for CPP-GMR devices using Gd21.7Fe78.3 free layers was reduced by 26% compared
to Gd27.5Fe72.5 free layers. The larger values of Ms exhibited by Gd21.7Fe78.3 layers may be attributed
to a reduction of switching current. Ultimately, we found that CPP-GMR devices with Gd21.7Fe78.3
free layers and Ag spacers are good candidates for the light modulator applications, particularly
advanced information display systems.
Broadcast Technology No.46, Autumn 2011 ●
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