Narrow Beam Ultrasonic Transducer Matrix Model for Projection Imaging of Biological Media

Abstract

The following paper presents an idea of minimising the number of connections of individual piezoelectric transducers in a row-column multielement passive matrix system used for imaging of biological media structure by means of ultrasonic projection. It allows to achieve significant directivity with acceptable input impedance decrease. This concept was verified by designing a model of a passive ultrasonic matrix consisting of 16 elementary piezoceramic transducers, with electrode attachments optimised by means of electronic switches in rows and columns. Distributions of acoustic field generated by the constructed matrix model in water and results of the calculations conformed well.

2-D directional ultrasonic passive matrix of 512 elementary transducers for projection imaging of biological structures

“…The concept of a passive matrix was verified by designing a matrix consisting of 16 elementary ultrasonic transducers in a 4 x 4 setup, with electrode attachments optimised by means of electronic switches in rows and columns [5,8]. A model of the passive ultrasonic matrix was constructed using transducers made of Pz37 Ferroperm piezoceramic plates which are 1.6 x 1.6 mm in dimension and 0.9 mm thick.…”

“…In most cases specialists use echographic methods (ultrasonography). The following work presents the potential of using information from ultrasonic pulses propagating through an object in order to produce images showing a projection of the studied structure [1,2,3,4,5] in the form of distribution of average values of the measured acoustic parameter for one or more surfaces perpendicular to the direction of incidence of ultrasonic waves (similarly to röentgenography). The use of specially designed multielement ultrasonic projection probes with fast electronic elementary transducer switching [3,4,5] allows acquiring images in pseudo-real time (e.g.…”

“…Passive matrix is the simplest matrix control solution. There are two groups of switches in this type of matrix: one for a selected active column and the other for a selected active row [5]. The transducer situated at the point of intersection of the selected row and column is activated this way.…”

“…Nevertheless, it is a non-destructive, non-invasive and safe method. The following work presents an innovative method of designing multielement ultrasonic probes (sending and receiving) as small flat two-dimensional passive matrices of piezoelectric transducers, that are used for projection imaging of the structure of biological media (especially soft tissue) in orthogonal projection, with the use of scanning method through switching of the right pairs of sending and receiving elementary transducers [3,4,5]. The constructed matrices were tested during real projection measurements on a research stand.…”

“…In the context of electric circuits the construction of the transducers (dielectrics with sprayed on electrodes) means that they are capacitive in nature and that therefore the activating signal can travel through inactive transducers to other column and row lines despite their switches being opened. The directivity and effectiveness/sensitivity of such a passive matrix largely depends on the distribution pattern of the activating signal on all elementary transducers, that are vibrated in this manner (with crosstalk) [4,5,8].…”