Disclosed is a graphene-based terahertz device that includes a top graphene layer, a bottom graphene layer, and a middle layer disposed between the top graphene layer and the bottom graphene layer. The middle layer is a liquid crystal layer, a piezocrystal layer, an ionic liquid layer, or an ion gel layer. Also disclosed are methods of preparing different embodiments of the above-described graphene-based terahertz device.

A multilayer backing absorber for use with an ultrasonic transducer comprises a plurality of absorber elements, each absorber element having at least one metal layer and at least one adhesive layer, wherein the backing absorber is adapted to be coupled to a vibrating layer of the ultrasonic transducer.

A coating device for sealant and a coating method for sealant coating are disclosed. The coating device includes a sealant storage pipe provided with two end portions; one end portion is connected to a gas jet means and the other end portion is connected to a nozzle; a pipe wall of the sealant storage pipe is made from a flexible material; and the pipe wall can be subjected to recoverable inward deformation perpendicular to an axial line of the sealant storage pipe. A coating method for sealant coating, comprising: subjecting a pipe wall to recoverable inward deformation perpendicular to an axial line of a sealant storage pipe during spraying; and subjecting the pipe wall to recovery when the spraying ends.

Sensors and methods of operating sensors are described herein. One sensor includes a number of III-nitride strain sensitive devices and a number of passive electrical components that connects each of them to one of the III-nitride strain sensitive devices.