The world's smallest ultrasonic detector is created

The ultrasonic detector is 100 times smaller than the average human hair, yet it can

visualize details that were previously unobservable. New super-resolution imaging will help in scientific research

Since the development of medical ultrasoundimaging in the 1950s, the main technology for detecting ultrasonic waves was primarily focused on the use of piezoelectric detectors that convert the pressure of ultrasonic waves into electrical voltage. The image resolution achieved with ultrasound depends on the size of the piezoelectric detector used. Decreasing this size results in a higher resolution. However, a further decrease in the size of piezoelectric detectors sharply reduces their sensitivity, making them unsuitable for practical use.

Silicon photonics technology is widelyIt is used to miniaturize optical components and pack them tightly on a small surface of a silicon chip. Although silicon does not exhibit piezoelectricity, its ability to confine light to less than optical wavelength has already been widely used to develop miniature photonic circuits.

Researchers from Helmholtz Zentrum Munchen and TUMtook advantage of these miniature photonic circuits to create the world's smallest ultrasonic detector: the Silicon Waveguide Reference Detector, or SWED. Instead of detecting voltage from piezoelectric crystals, SWED monitors changes in the intensity of light propagating through miniature photonic circuits.

“This is the first time that the detector is smallerblood cells are used to detect ultrasound using silicon photonics technology, explains Rami Schneiderman, developer of SWED. "If the piezoelectric detector were downsized to the SWED scale, it would be 100 million times less sensitive."

“The extent to which we were able to miniaturizethe new detector, while maintaining high sensitivity through the use of silicon photonics, was simply breathtaking, ”emphasizes Professor Vasilis Ntsiahristos, head of the research team. The SWED is about half a micron (= 0.0005 millimeters). This size corresponds to an area that is at least 10,000 times smaller than the smallest piezoelectric detectors used in clinical imaging applications. SWED is also up to 200 times smaller than the ultrasound wavelength used, which means it can be used to render parts less than one micrometer in size, resulting in so-called ultra-high resolution imaging.

“The detector was originally designed to improvecharacteristics of optoacoustic imaging, which is the main focus of our research at Helmholtz Zentrum München and TUM. However, we now envision its application in the broader field of sensing and visualization, ”concludes Ntsiahristos.

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