Ultrasonic array for haptic rendering

Inventors

Fedder, Gary K. • Rozsa, Jace

Abstract

A wearable, low power, compact ultrasonic haptic device that focuses ultrasound at or below the skin's surface using a piezocomposite transducer consisting multiple arrayed acoustic pixels, each acoustic pixel comprising an array of piezocomposite pillars separated by an epoxy and topped by a metal electrode. The high efficiency of the piezocomposite transducer facilitates sufficient production of ultrasonic energy directed at a focal point at or below the surface the skin to stimulate a tactile sensation.

Core Innovation

The invention is a device for tactile ultrasound haptic rendering that uses an array of pillars composed of a piezocomposite material. A plurality of electrodes each covers a subset of the array of pillars to form an acoustic pixel. A matching layer covers the acoustic pixels, where the matching layer has an acoustic impedance between the acoustic impedance of the piezocomposite material and the acoustic impedance of a target material.

The matching layer is segmented into a plurality of segments corresponding to each acoustic pixel. Ultrasonic energy generated by the device is directed at a focal point at or below the surface of a user's skin to stimulate a tactile sensation. The device is configured to focus the ultrasound at or below the skin surface using independent element time-delayed phasing of acoustic pixels so that wavefronts converge at the focal point.

The pillars are formed as acoustic pixels from piezocomposite material using epoxy-filled high-aspect-ratio PZT pillars topped with patterned copper/tin electrodes. The acoustic impedance matching layer reduces reflection using an impedance-matching layer configuration, and an optional segmented coupling layer is described as nanoparticle-tunable. Experimental results described include measurable wavefront shaping, an amplitude increase for phased-array focusing, increased pressure for quarter-wave matching versus none, and a tactile threshold test where participants perceived tactile sensation.

Claims Coverage

The independent claim provides a complete device architecture for a tactile ultrasound system with piezocomposite pillar acoustic pixels, pixel-associated electrodes, and a segmented acoustic impedance matching layer. The inventive features focus on impedance-matched, pixel-segmented transduction and directing ultrasonic energy to a focus at or below skin to stimulate tactile sensation.

Overall, the claim coverage centers on combining piezocomposite pillar acoustic pixels with electrode-defined pixel subsets and a segmented acoustic impedance matching layer sized to each pixel, while directing focused ultrasonic energy at or below the skin surface to stimulate tactile sensation.

Stated Advantages

Documented Applications