Ultrasound transducer and method for making the same

Abstract

The present application provides a multilayer lateral mode coupling method for phased array construction and transducer devices built accordingly. This disclosure describes and demonstrates that the electrical impedance of a phased array can be substantially reduced and readily controlled to be close to the source impedance. The fabrication process is relatively simple and inexpensive. In addition, the elements are robust for use in 1.5, 2, 3 or other dimensional configurations, over an extended period of operation, without structural failure, and providing a high power output required for imaging and/or medical therapy applications.

What is claimed is: 
     
         1 . A method for fabricating an acoustic array of transducer elements, comprising:
 providing a plurality of acoustic transducer elements, wherein each acoustic transducer element is formed by:
 providing a plurality of piezoelectric layers, each piezoelectric layer having a respective plurality of dimensions defining its spatial extent, including a first dimension along a first axis along which said piezoelectric layer radiates acoustic energy when excited by an electrical driving signal applied along a second axis that is perpendicular to said first axis, each piezoelectric layer having a signal electrode and a ground electrode; and 
 providing a plurality of conducting foils acting as electrodes to deliver electrical driving signals to the piezoelectric layers, wherein said conducting foils are interspersed between said plurality of piezoelectric layers to define a set of signal electrodes spatially interleaved with a set of ground electrodes, such that an adjacent pair of piezoelectric layers share a single electrode lying therebetween; and 
 connecting said set of signal electrodes form a common signal electrode and connecting said set of ground electrodes form a common ground electrode, said common ground electrode comprising outer ground electrodes extending along outer sides of the transducer element such that said second axis is perpendicular to said outer ground electrodes; and 
   mechanically arranging said plurality of acoustic transducer elements along at least a direction perpendicular to said first axis such that outer ground electrodes of an adjacent pair of transducer elements are brought into electrical communication.   
     
     
         2 . The method of  claim 1 , said arranging comprising arranging the piezoelectric layers along a single axis with respect to one another. 
     
     
         3 . The method of  claim 1 , said arranging comprising arranging the piezoelectric layers along two dimensions, both being perpendicular to said first axis. 
     
     
         4 . The method of  claim 3 , further comprising application of low temperature solder to a surface of said array so as to couple the piezoelectric layers thereto. 
     
     
         5 . A method for fabricating an acoustic array of transducer elements, comprising:
 providing a plurality of acoustic transducer elements, each having a respective plurality of dimensions defining its spatial extent, including a first dimension along a first axis along which said acoustic transducer element radiates acoustic energy when excited by an electrical driving signal applied along a second axis that is perpendicular to said first axis, each acoustic transducer element comprising:
 a plurality of piezoelectric layers, wherein each piezoelectric layer is mechanically responsive, along said first axis, to a received electrical driving signal, so as to vibrate along said first axis upon application of the received electrical driving signal by a pair of electrodes electrically coupled to corresponding opposing faces of said each piezoelectric layer along said second axis; 
 wherein said plurality of piezoelectric layers are arranged with respect to one another so that a common electrode disposed between two adjacent piezoelectric layers is shared between said two adjacent piezoelectric layers; 
 wherein a first set of non-adjacent common electrodes are connected in parallel to form a common signal electrode, and wherein a second set of non-adjacent common electrodes are connected in parallel to form a common ground electrode, said common ground electrode comprising outer ground electrodes extending along outer sides of each transducer element such that said second axis is perpendicular to said outer ground electrodes; 
   the method further comprising:   mechanically arranging said plurality of acoustic transducer elements along at least a direction perpendicular to said first axis such that outer ground electrodes of an adjacent pair of transducer elements are brought into electrical communication.