Using a flattened SiO2/Cu electrode/36–48° LiTaO3 structure, a small (5×5 mm2) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US personal communication services (PCS) was realized by the authors. However, a smaller duplexer is strongly required. Using the flip-chip bonding process of SAW chips and a Rayleigh SAW propagating on a flattened SiO2/Cu electrode/126–128° YX-LiNbO3 structure, which has a larger coupling factor than the above-mentioned substrate, a smaller (3×2.5 mm2) SAW duplexer with a good TCF was realized.

A lactic acid monomer has an asymmetric carbon in the molecule, so there are optical isomer l- and d-type. The most widely used poly(lactic acid) (PLA) for commercial applications is poly(l-lactic acid) (PLLA). PLLA is the polymerization product of l-lactide. Certain treatments of PLLA can yield a film that exhibits shear piezoelectricity. Thus, piezoelectric PLLA fiber can be generated by micro slitting piezoelectric PLLA films or by a melt spinning method. We prepared left-handed helical multi fiber yarn (S-yarn) and right-handed helical yarn (Z-yarn) using piezoelectric PLLA fiber. PLLA exhibited shear mode piezoelectricity, causing the electric polarity of the yarn surface to be reversed on the S-yarn and Z-yarn when tension was applied. An SZ-yarn was produced by combining the S-yarn and Z-yarn, and fabric was prepared using the SZ-yarn. This study demonstrated that the fabric has a strong antibacterial effect, which is thought to be due to the strong electric field between the yarns. The field is generated by a piezoelectric effect when the fabric was extended and contracted.

Using flattened-SiO 2 /Cu-electrode/36∼48 • LiTaO 3 structure, small size (5×5mm 2 ) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US-PCS was realized by authors. However, a smaller duplexer has been strongly required. Using flip-chip bonding process of SAW chips and Rayleigh SAW propagating on the flattened-SiO 2 /Cuelectrode/126∼128 • YX-LiNbO 3 , which has larger coupling factor than above-mentioned substrate, a smaller sized (3×2.5mm 2 ) SAW duplexer with a good TCF has been realized.

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