Ultrafine scale piezoelectric composite materials for high frequency ultrasonic imaging arrays

Abstract

Intravascular and endoscopic acoustic imaging typically require high ultrasonic operating frequencies, over 7 MHz. At these frequencies the ceramic transducer dimensions become very small; pitches in the order of 20 to EOpm are existing interconnect approaches and be fabricated at low needed. Moreover, such arrays must be compatible with cost. These piezoelectric transducer array requirements severely challenge the ability of conventional ET ceramic technologies in terms of cost-effective fabrication.To meet the demand for such transducer shapes, MS1 has developed a net shape ceramic injection molding process for production of piezoelectric ceramics in complex shapes.Using this technique, MS1 has produced ultrafine scale 2-2 piezocomposite arrays having FZI elements less than 25pm wide and pitches under 50pm. This paper reviews recent advances in the net shape molding technology, and compares the characteristics of an injection molded 7 MHz 2-2 configuration with that of a similar array prepared by conventional dicing.

Microfabrication of Ceramics by Co‐extrusion

“…For example, Stevenson et al 15 reported PZT elements 20 m thick produced by laminating sintered tape cast sheets. Injection molding method have been developed 16 capable of producing features on the order of 22 m.…”

Microfabrication of electrode patterns for high-frequency ultrasound transducer arrays

“…recently there have been some successful attempts to increase the operating frequency of composites using conventional dice-and-fill techniques [8], injection molding [9], laser micromachining [10], and interdigital pair bonding [11], as well as deep reactive ion etching of single-crystal materials [12]. However, although these techniques suffice to make standard medical imaging transducers and research devices operating up to 40 MHz, the fabrication of the composites becomes very difficult at higher frequencies because of the ultrafine lateral features required for efficient operation, and design compromises must be introduced, for example, relating to ceramic volume fraction.…”

Análise de materiais piezelétricos compósitos para aplicações em transdutores de ultra-som.

“…Após a cura do polímero, o compósito é aquecido, e é aplicado um forte campo elétrico (da ordem de kV/mm) para polarizar as partículas de material piezelétrico. Para construir compósitos com conectividade 1-3 e 2-2 em larga escala, é geralmente utilizado moldagem por injeção (PAZOL et al, 1995). Nesse processo é misturado pó de material piezelétrico com uma espécie de cola e em seguida a mistura é colocada num molde previamente fabricado.…”