A mobile device includes one or more piezoelectric polymer layers underlying a display. The one or more piezoelectric polymer layers may be electrically driven to operate in either a d33 stretching mode or a d31 bending mode. The mobile device functions as an ultrasonic sensor in the d33 stretching mode and as an audio speaker/microphone or a proximity sensor in the d31 bending mode. The piezoelectric polymer layer operating in the d31 bending mode may be directly mechanically coupled to a display, indirectly mechanically coupled to the display and underlying an ultrasonic sensor stack, or integrated in the ultrasonic sensor stack. Signal performance of the piezoelectric polymer layer operating in the d31 bending mode may be enhanced or modulated by having a larger area, multiple layers, bi-pole or uni-pole driving with multiple layers, one or more stiff adhesives, a spacer layer, one or more mass features, a thin TFT layer, a thick piezoelectric polymer layer, or combinations thereof.

An electrostatic zipping actuator includes a primary electrode, a secondary electrode overlying the primary electrode, a dielectric layer located between and abutting at least a portion of the primary electrode and the secondary electrode, and a dielectric fluid disposed at least at a junction between the dielectric layer and one of the electrodes, where an average total thickness of the dielectric layer is less than approximately 10 micrometers.

A piezoelectric sensor, comprising: a stress applying layer in which a plurality of stress applying grooves extending in parallel with a first direction are formed in a predetermined region on a whole surface; and a piezoelectric layer that is layered on the stress applying layer and formed from a polymer piezoelectric material containing an optical active polymer.

An embodiment piezoelectric element includes a piezoelectric composite layer including a polymer and a piezoelectric ceramic, a backing layer disposed on a rear surface of the piezoelectric composite layer and configured to limit vibration of the piezoelectric composite layer, and an adhesive layer bonding the piezoelectric composite layer and the backing layer.

The present invention relates to an actuator including: a first ionic polymer layer disposed on underside of a first electrode layer; a second ionic polymer layer disposed on top of a second electrode layer; and a porous conducting interlayer disposed between the first ionic polymer layer and the second ionic polymer layer.

A piezoelectric substrate, comprising: a conductor cord that has a core material and a conductor disposed around the core material; and an elongated piezoelectric body that is disposed around the conductor cord in a spiral manner, unidirectionally along an axial direction of the conductor cord, wherein: the piezoelectric body comprises an optically active helical chiral polymer, a lengthwise direction of the piezoelectric body and a main orientation direction of the helical chiral polymer in the piezoelectric body are substantially parallel to each other, the piezoelectric body has an orientation degree F. of from 0.5 to less than 1.0, and the conductor cord satisfies Formula (b): ΔD.sub.max<t.sub.pmin, wherein ΔD.sub.max is a maximum value of a difference in height between a division A that is selected from plural divisions and a division B that is adjacent to the division A, and t.sub.pmin is a minimum thickness of the piezoelectric body.

A display apparatus includes a display panel configured to display an image and a sound generating device on a rear surface of the display panel. The sound generating device is configured to vibrate the display panel to generate sound. The sound generating device includes a first structure and a first passivation layer on one side of the first structure, at least a portion of the first passivation layer having a non-flat shape.

A piezoelectric transducer is provided herein, comprising a three-dimensional structure made of a plurality of peptides, the peptides being self-assembling and the structure being piezoelectric, wherein at least a portion, or each, of said plurality of peptides comprises peptides of 2 to 10 amino acid residues, provided that the plurality of peptides is not consisted of a plurality of Phe-Phe dipeptides. Further described herein are peptides having an amino acid sequence Hyp-Phe-Phe, Boc-Dip-Dip, (L)Trp-(D)Trp or (D)Trp-(L)Trp, as well as three-dimensional structures comprising such peptides.

An electroactive polymer actuator includes an electroactive polymer structure and a driver for providing an actuation drive signal. In one aspect, a first drive level is used to charge the electroactive polymer structure from a non-actuated state to an actuated state. When or after the electroactive polymer structure reaches the actuated state, a lower second drive level is used to hold the electroactive polymer structure at the actuated state. This temporary overdrive scheme improves the speed response without damaging the electroactive polymer structure. In another aspect, a driving method makes use of several different level segments over time, which compensates for the delayed actuation response of the EAP actuator.

Photo-detectors disclosed include at least one of a thin film or a heterostructure of photo-sensitive material and a pair of Ohmic contacts coupled to the at least one of the thin film or the heterostructure. The at least one of the thin film or the heterostructure is configured to be under a strain gradient to induce shift current flow within the material to perform photo-detection in a frequency range that includes a mid-infrared frequency range. The photo-detectors provided for can include a variety of configurations, such as a lateral configuration or a vertical configuration, and can operate in self-powered and negative illumination regimes. Associated methods are also provided, which can include inducing a strain gradient and performing photo-detection in a frequency range that includes a mid-infrared frequency range.