A composite fiber composed of at least a metal sintered body and a ceramic sintered body. In the composite fiber, the metal sintered body and the ceramic sintered body are adjacent to each other. The composite fiber having the metal sintered body and the ceramic sintered body can have a tensile strength of 5 kgf/mm.sup.2 or more.

Provided is a piezoelectric structure including a braid composed of a conductive fiber and piezoelectric fibers, the braid being a covered fiber having the conductive fiber as the core and the piezoelectric fibers covering the periphery of the conductive fiber, wherein the covered fiber has at least one bent section, and when the piezoelectric structure is placed on a horizontal surface, the height from the horizontal surface to the uppermost section of the piezoelectric structure is greater than the diameter of the covered fiber.

A very small piezoelectric sensor capable of being mass produced includes a core, a piezoelectric layer on a surface of the core; and a conductive layer on a surface of the piezoelectric layer away from the core. The core is flexible and threadlike, the core is a first electrode of the piezoelectric sensor, and the conductive layer is a second electrode of the piezoelectric sensor. An array of such sensors allows the “skin” of a robot for example to simulate the sensitivity of hair-covered human skin. A method for making the piezoelectric sensor and an electronic device using the piezoelectric sensor are also disclosed.

A barium titanate fiber is useful as a filler for a polymer composite piezoelectric body, a polymer composite piezoelectric body has high piezoelectric properties, and a piezoelectric element utilizes the polymer composite piezoelectric body. In the barium titanate fiber, the molar ratio of barium atoms to titanium atoms (Ba/Ti ratio) falls within the range of 1.01 to 1.04. The polymer composite piezoelectric body includes a resin composition containing the barium titanate fiber and a polymer. The piezoelectric element including an electrically conductive layer on one surface or both surfaces of the polymer composite piezoelectric body.

A resin structure that includes a plurality of piezoelectric fibers that generate a charge by application of external energy; and an insulating resin coating at least one of the plurality of piezoelectric fibers.

A flexible vibration module is disclosed. The flexible vibration module includes a piezoelectric composite layer, including: a plurality of piezoelectric portions each having a piezoelectric characteristic, where at least two of the plurality of piezoelectric portions have different sizes; and a flexible portion between the plurality of piezoelectric portions.

A flexible vibration module is disclosed. The flexible vibration module includes a piezoelectric composite layer, including: a plurality of piezoelectric portions each having a piezoelectric characteristic, where at least two of the plurality of piezoelectric portions have different sizes; and a flexible portion between the plurality of piezoelectric portions.

A structure includes an oriented piezoelectric polymer arranged in a circular tubular or circular columnar shape, wherein the orientation angle of the piezoelectric polymer with respect to the central axis of the structure is 15° to 75°, the piezoelectric polymer includes a crystalline polymer having an absolute value of 0.1 to 1000 pC/N for the piezoelectric constant d14 when the orientation axis is the third axis, and the piezoelectric polymer includes a P-body containing a crystalline polymer with a positive piezoelectric constant d14 value and an N-body containing a crystalline polymer with a negative value, wherein for the portion of the central axis of the structure having a length of 1 cm, the value of T1/T2 is 0 to 0.8, T1 being the smaller and T2 being the larger of (ZP+SN) and (SP+ZN), where ZP, SP, ZN, and SN are particularly defined masses.

A mask that exhibits a more improved antibacterial effect by more efficiently expanding and contracting a body of the mask in the periphery of the nose and mouth area of the mask without using a drug such as an antibacterial agent and/or an antiviral agent. The mask includes: a body including a yarn having a potential generating filament; and at least one dart that extends from an edge portion of the body towards a central portion of the body.

The present invention can provide a fiber having a further enhanced strength while serving as a ceramic fiber. To this end, a composite fiber according to the present invention a first fiber component member made of a material having a volume resistivity of 5×10.sup.−6 to 5×10 .sup.6 Ω.Math.m, or a material of a semiconductor or metalloid; and a second fiber component member comprising a ceramic material, wherein the first fiber component member and the second fiber component member are adjacent to each other such that the first and second fiber component members form a fibrous body.