The disclosure belongs to the technical field of additive manufacturing, and discloses a flexible piezoelectric sensor based on 4D printing and a preparation method thereof. The sensor includes a magnetic part and a conductive part, wherein: the conductive part includes two substrates disposed opposite to each other and a spiral structure disposed between the two substrates. Both the two substrates and the spiral structure are made of conductive metal materials. The magnetic part has a flexible porous structure and is arranged between the two substrates to generate a magnetic field. When the substrate is subjected to external pressure, the spiral structure and the magnetic part are compressed simultaneously, the magnetic flux passing through the spiral structure changes, and the voltage of the two substrates changes, by measuring the voltage change of the two substrates to reflect the change of external pressure, the pressure measuring process is achieved.

A cooling system and method for using the cooling system are described. The cooling system includes a plurality of individual piezoelectric cooling elements spatially arranged in an array extending in at least two dimensions, a communications interface and driving circuitry. The communications interface is associated with the individual piezoelectric cooling elements such that selected individual piezoelectric cooling elements within the array can be activated based at least in part on heat energy generated in the vicinity of the selected individual piezoelectric cooling elements. The driving circuitry is associated with the individual piezoelectric cooling elements and is configured to drive the selected individual piezoelectric cooling elements.

Example methods include depositing a precursor layer onto a substrate where the precursor layer includes droplets comprising a polymerizable material, inducing a phase inversion in the precursor layer to obtain a modified precursor layer including droplets of a non-polymerizable liquid within a polymerizable liquid mixture, and polymerizing the polymerizable liquid mixture to obtain a nanovoided polymer element. Examples include devices fabricated using nanovoided polymer elements fabricated using such methods, including electroactive devices such as actuators and sensors.

An optical element includes a nanovoided polymer layer having a first refractive index in an unactuated state and a second refractive index different than the first refractive index in an actuated state. Compression or expansion of the nanovoided polymer layer, for instance, can be used to reversibly control the size and shape of the nanovoids within the polymer layer and hence tune its refractive index over a range of values, e.g., during operation of the optical element. Various other apparatuses, systems, materials, and methods are also disclosed.

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 backing panel for a transducer of an ultrasound scanner probe, comprising a core layer sandwiched by a first skin layer and a second skin layer. The transducer may comprise a front portion and a rear portion, where the front portion points to a direction of a target for the ultrasound scanner probe, and the first skin layer is adjacent to the rear portion of the transducer.

A piezoelectric device includes: a base having at least one hole, a heat conductive portion disposed in the at least one hole and in contact with a wall of the at least one hole, and at least one piezoelectric sensor disposed on the base. A thermal conductivity of the heat conductive portion is greater than a thermal conductivity of the base. Each piezoelectric sensor includes: a first electrode, a piezoelectric pattern made of a piezoelectric material and a second electrode that are sequentially stacked in a thickness direction of the base.

Certain aspects provide an integrated circuit (IC) including a resonator. One example IC generally includes a substrate, a first oxide region disposed above the substrate, and a resonator. The resonator may include a piezoelectric layer, a second oxide region disposed below the piezoelectric layer and bonded to the first oxide region, and a cavity in the second oxide region, wherein at least a portion of the second oxide region is below the cavity.

A display device includes a scanned projector for projecting a beam of light, and a diffraction grating for dispersing the light at a plurality of angles into a waveguide, wherein at least a portion of the diffraction grating includes a nanovoided polymer. Manipulation of the nanovoid topology, such as through capacitive actuation, can be used to reversibly control the effective refractive index of the nanovoided polymer and hence the grating efficiency. The switchable grating can be used to control the amount of diffraction of an incident beam of light through the grating thereby decreasing optical loss. Various other methods, systems, apparatuses, and materials are also disclosed.

In some examples, a device includes a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode.