An electroactive material actuator and sensor is actuated with an actuation signal having an activation period for charging the actuator and a de-activation period for discharging the actuator. A parallel resistance of the actuator is determined by sensing a steady state current during the activation period and a series capacitance of the actuator is determined based on a charge flow during charging of the actuator at the beginning of the activation period. A series resistance is obtained by controlling a current through the actuator with an oscillating profile so that a phase relationship of the actuator between current and voltage can be measured. An oscillating current sink is used to enable circuit component measurements, which implement sensing functionality.

The invention relates generally to electroactive material actuators (and combined sensor-actuators) having embedded magnetic particles (42) for facilitating enhanced actuation and/or sensing effects.

Provided is a piezoelectric film capable of realizing an electroacoustic conversion film or the like in which the durability is high and a sufficient sound pressure with respect to an input operating voltage is obtained. The piezoelectric film is a piezoelectric film including a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material, and electrode layers which are provided on both surfaces of the polymer-based piezoelectric composite material, in which in a case where a cross section of the piezoelectric film in a thickness direction is observed with a scanning electron microscope, the polymer-based piezoelectric composite material is divided into two equal regions in the thickness direction, and void volumes of the two regions are measured, a ratio of the void volume obtained by dividing the void volume of the region with a larger void volume by the void volume of the region with a smaller void volume is 1.2 or greater.

The present invention provides a polymer-based piezoelectric composite material from which a piezoelectric film capable of outputting a higher sound pressure is obtained in a case of using a piezoelectric speaker, a piezoelectric film formed of the polymer-based piezoelectric composite material, and a piezoelectric speaker and a flexible display which are formed of the piezoelectric film. The polymer-based piezoelectric composite material of the present invention is a polymer-based piezoelectric composite material including a polymer matrix which contains a polymer having a unit represented by Formula (1), and at least one unit selected from the group consisting of, a unit represented by Formula (2-1), a unit represented by Formula (2-2), and a unit represented by Formula (2-3), and piezoelectric particles.

(MO.sub.x/2)  Formula (1)

(R.sup.1SiO.sub.3/2)  Formula (2-1)

(R.sup.2.sub.2SiO.sub.2/2)  Formula (2-2)

(R.sup.3.sub.3SiO.sub.1/2)  Formula (2-3)

Provided are a polymer-based piezoelectric composite material and a piezoelectric film which have high productivity and are capable of suppressing degradation of piezoelectric conversion efficiency in an environment where the temperature and the humidity are severe. The polymer-based piezoelectric composite material is a polymer-based piezoelectric composite material including piezoelectric particles in a matrix containing a polymer material, in which the polymer-based piezoelectric composite material contains greater than 500 ppm and 10000 ppm or less of a substance on a mass basis which has an SP value of less than 12.5 (cal/cm.sup.3).sup.1/2 and is in a liquid state at room temperature, voids are formed in the polymer-based piezoelectric composite material, and an area ratio of the voids in a cross section of the polymer-based piezoelectric composite material is 0.1% or greater and 20% or less.

The present invention provides a polymer-based piezoelectric composite material from which a piezoelectric film capable of outputting a higher sound pressure is obtained in a case of using a piezoelectric speaker, a piezoelectric film formed of the polymer-based piezoelectric composite material, and a piezoelectric speaker and a flexible display which are formed of the piezoelectric film. The polymer-based piezoelectric composite material of the present invention is a polymer-based piezoelectric composite material including a polymer matrix which contains a polymer containing a group represented by Formula (1), and piezoelectric particles.

*-L.sup.1-CR.sup.1R.sup.2—CN  Formula (1) In Formula (1), L.sup.1 represents a divalent linking group excluding a divalent aliphatic hydrocarbon group. R.sup.1 and R.sup.2 each independently represent a hydrogen atom, an alkyl group, or an aryl group.

A method is provided for manufacturing a dielectric elastomer transducer including a dielectric elastomer layer and electrode layers sandwiching the elastomer layer. The elastomer layer when stretched exhibits a stress-strain curve having: a low strain and high elasticity region; a low elasticity region; and a high strain region. The method includes: a pre-stretching process to reduce hysteresis in elastic behavior of the elastomer layer by stretching the elastomer layer one or more times under a load as heavy as a first load before the electrodes are provided, each stretching causing the elastomer layer to undergo a tension falling in the low elasticity region; and a dielectric elastomer layer fixing process including applying a second load smaller than the first load to the elastomer layer so as to fix the elastomer layer to a support member under a second tension smaller than the first tension.

A device may include an inner layer comprising a polyvinylidene fluoride (PVDF) material. The device may also include a first interface layer, disposed on a first side of the inner layer, and a second interface layer, disposed on a second side of the inner layer. The first interface layer and the second interface layer may comprise a mixture of PVDF material and a scavenger component.

An example device includes a nanovoided polymer element, a first electrode, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. In some examples, the nanovoided polymer element may include anisotropic voids. In some examples, anisotropic voids may be elongated along one or more directions. In some examples, the anisotropic voids are configured so that a polymer wall thickness between neighboring voids is generally uniform. Example devices may include a spatially addressable electroactive device, such as an actuator or a sensor, and/or may include an optical element. A nanovoided polymer layer may include one or more polymer components, such as an electroactive polymer.

Multicomponent fibers with a piezoelectric effect, including an electroactive fluoropolymer shell which adheres to a metal core. Also, a solvent-based fluoropolymer formulation which makes it possible to obtain optimum adhesion to a bare, electrically conductive metal filament. Also, a process for manufacturing these composite fibers, and also their uses in varied sectors of technical textiles, filtration and in electronics.