Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Doppler flow transducer

Invasive Doppler probes are used to assess blood flow in a wide range of applications (vascular surgery, cardiovascular surgery, neurosurgery, endoscopy). The probes used for these applications are single element high frequency (16MHz, 20MHz) transducers with high sensitivity. As probes are used invasively, they must be sterilized prior to use, preferably by steam sterilization methods. Gas (EO), Plasma or Formaldehyde sterilization methods are also widely used. Restrictions may apply for some fields of use.

The probes are reusable due to their high price. Depending on the application, probes are needed in different sizes.

Reference devices working at 16MHz with diameters of 1.0mm and 2.0mm, which are the most commonly used probes, were manufactured using PZT bulk ceramics.

These reference devices were tested and characterized and in-vivo measurements were carried out.

PiezoCAD simulation software was used for modelling the devices.

Using doped PZT, PNNZT and PLZT, demonstrators were designed and fabricated in considerable quantity.

The demonstrators were characterized and tested in-vitro and in-vivo using lab equipment and a commercially available Doppler device.

Good to excellent results were obtained for 16MHz/2mm probes with all three types of piezoceramics. For 16MHz/1mm probes, good results could be obtained with doped PZT and PNNZT materials. With PLZT it was difficult to build good 16MHz/1mm probes.

Probes made with doped PZT and PNNZT behaved well at temperatures up to 140°C.

Probes made with PLZT were gradually destroyed at temperatures above 80°C.

16MHz/1mm probes built with PNNZT and 16MHz/2mm probes built with PNNZT and PLZT are still in use with good results in two hospitals.

All types of demonstrators could be sterilized with gas (EO), low temperature Plasma or Formaldehyde more than 20 times without loosing quality. Probes made with doped PZT and PNNZT kept the quality for 5 cycles of steam sterilization then gradually started loosing sensitivity.

Probes made with PLZT were destroyed after the first cycle of steam sterilization.

Within a few weeks we will start manufacturing 16MHz probes using PNNZT materials.

We find an increasing demand for invasive Doppler probes and we expect to increase production volume from two hundred probes per year to more than a thousand per year within the next two years.

New fields of applications will be identified to further increase production quantity.

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Medizintechnik Basler AG
Schulstrasse 161
8105 Regensdorf
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