Micromachined rayleigh, lamb, and bulk wave capacitive ultrasonic transducers
US6295247A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1999 |
| Grant date | Sep 25, 2001 |
| Priority date | — |
| Expiry date | Oct 1, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/46
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A micromachined capacitive ultrasonic transducer is used to generate and detect Rayleigh, Lamb, and bulk waves in a solid substrate. The transducer contains a substrate with a conductive back electrode, a support material on the substrate, a membrane supported above the substrate by the support material, and a conductive film on the membrane. The support material contains parallel edges defining elongated gaps over which the membrane is supported. Unsupported free regions of the membrane above the gaps are vibrated by applying an electrical signal between the conductive film and conductive back electrode, and stresses are coupled into the substrate at the attachment edges of the membrane. Acoustic modes of the substrate are excited by the stresses, and ultrasonic waves propagate in a direction perpendicular to the parallel edges. By properly choosing the membrane width, material, and thickness, the gap separation distance, and the support material height and thickness, a particular acoustic mode can be selected for a required operating frequency. The gaps may be separated by a distance equal to the wavelength or half-wavelength of the desired acoustic mode. Alternately, the gaps ma…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.