Siemens Medical acquires pioneer of silicon-based ultrasound transducers

Siemens Medical Solutions ultrasound division has acquired Sensant, a developer of silicon-based ultrasound transducer technology, for an undisclosed price.

Acquisition of the privately held company based in San Leandro, CA, will enable Siemens to produce and sell next-generation products based on capacitive microfabricated ultrasonic transducer (CMUT) technology. Sensant pioneered this technology, which is expected to provide high-quality volumetric sonography. Siemens plans to eventually integrate the transducer technology into all its ultrasound imaging systems.

The commercial benefits of CMUT, however, may be at least two years away, and achieving them will be no small task. Siemens engineers must first evaluate the technology, said Klaus Hambuechen, president and CEO of Siemens' ultrasound division.

"We need to see what can be done with the completely different geometry and frequency rate of these transducers," he said. "We want to work on some prototypes."

The assessment and, ultimately, the incorporation of this technology into Siemens ultrasound scanners will depend on the integration of Sensant and its engineers with Siemens. Sensant will eventually be combined with Siemens' ultrasound division, based in Mountain View, CA.

"Sensant will continue to exist, but only for a short period," Hambuechen said. "We are already bringing some of their people onto our campus."

Following finalization of the deal, teams from both companies began almost immediately to coordinate technology and product planning and development, said Ron Ho, vice president for Siemens ultrasound division and primary project manager for the acquisition. The two companies had been collaborating for about two years, and the acquisition was the logical next step.

"Consider it a long due diligence," Ho said. "We've had a technical relationship with the scientists and entrepreneurs on the Sensant side."

The acquisition and the CMUT technology will have an enormous business impact on Siemens and on the ultrasound industry in general, according to Ho.

"This is probably the biggest shift in technology since ultrasound was first developed," he said.

CMUT technology represents a radically different approach in transducer technology, serving as an alternative to the ceramic-based piezoelectric technology that has been used for decades to convert acoustic waves into images.

"Everyone in the world today uses the same PZT technology for making ultrasonic transducers," Ho said.

In contrast to conventional technology, CMUT transducers are made from silicon wafers, using integrated circuit fabrication processes. The drum-shaped structures vibrate when sending and receiving ultrasonic waves. They are so small that seven drums placed side-to-side have the diameter of a single human hair.

To make standard-size, large-area transducers, many thousands of drum heads are grouped together. Engineers might, however, use the CMUT technology for some unconventional applications, such as the development of transducers that fit inside catheters to enhance clinicians' visualization of functionality within the heart.

The improved integration of transducer and ultrasound system made possible with CMUT is expected to boost the effectiveness of volumetric imaging, a key area for its application, Ho said. It should also enable higher frequency imaging, which in turn will allow clinicians to view areas within the body in microscopic detail. The integrated circuit technology is also expected to cut the cost of manufacturing transducers.

"It lets you do mass production much less expensively," Ho said.

Integrated circuitry can also enhance quality control and manufacturing processes. PZT technology requires a number of manual processes and provides a suboptimal yield, he said.

"CMUT promises to allow a (comparatively) high-yield, high-performance process, because silicon-based technology is made in a very tightly controlled environment," he said.

The Sensant acquisition portends these technical advantages and more. Other companies are developing CMUT technology, and the first to market will have an edge over the rest of the industry.

"It will be a race, but we think we have made the right decision to give us the lead in this race," Hambuechen said. "Sensant is the group that has developed the most advanced technology."