Ultra-Compact Silicon Photonic SWEDs Offer Cheaper, Higher-Resolution Ultrasound Imaging
10,000 times smaller than piezoelectric ultrasound detectors, the new SWEDs cost less and offer super-resolution imaging capabilities.
A team working at the Helmholtz Zentrum München and the Technical University of Munich (TUM) have developed what they claim is the world's smallest ultrasound detector, based on silicon photonics and measuring a hundredth the width of a human hair: the silicon waveguide-etalon detector (SWED).
"This is the first time that a detector smaller than the size of a blood cell is used to detect ultrasound using the silicon photonics technology," says Rami Shnaiderman, developer of the SWED device, of the team's breakthrough. "If a piezoelectric detector was miniaturized to the scale of SWED, it would be 100 million times less sensitive."
An individual SWED detector itself measures around half a micron, or a hundred times smaller than the width of a human hair. Compared to a traditional piezoelectric sensor, of the type used in clinical environments for ultrasound imaging, it's 10,000 times smaller — and, thanks to its small size, can image features smaller than a single micrometer for super-resolution imaging.
The SWED works not by recording voltages output by piezoelectric crystals, as with a traditional ultrasound detector, but by monitoring the changing intensity of light as it passes through the photonic circuits that make up the silicon chip. By using the same manufacturing technology as other silicon chips, both the size and the cost are improved — the team claims a SWED can be produced at a tiny fraction of the cost of a piezoelectric detector.
The team's latest paper is not yet publicly available, but an earlier publication on SWED technology can be found under open-access terms on arXiv.org.