At North Carolina State University, researchers have performed a remarkable trick, namely producing ultrasound images using nothing but piezoelectric organic light emitting diodes. This may be a big deal, as existing ultrasound devices rely on electronics and image reconstruction algorithms to convert sonic waves captured by transducers into intuitive renderings. Avoiding these altogether may allow for much cheaper, smaller, and more capable ultrasound systems, potentially revolutionizing the entire industry. The researchers believe that conventional devices, that currently cost tens of thousands of dollars, may soon be replaced by the new direct imaging approach that would result in ultrasounds costing only hundreds of dollars each to produce. “Conventional ultrasound devices have a receiver that detects ultrasonic waves and converts them into an electrical signal, which is then sent to a computer that processes the signal and converts it into an image,” said Xiaoning Jiang, co-corresponding author of the study and Professor of Mechanical and Aerospace Engineering at North Carolina State. “We’ve created a device that effectively eliminates the electrical signal processing altogether.” Since the receiver is powered by the very ultrasonic currents it captures, there’s no need for a battery or another electric power source. The receiver uses piezoelectric crystals, which produce electricity when vibrated, coupled to organic light emitting diodes (OLEDs). As ultrasonic waves strike the crystals, the electricity generated is used to activate the OLEDs. The stronger the waves, the brighter the OLEDs illuminate. Luminances of up to 1,000 cd/m2 have already been recorded, which is quite bright when there’s not even a power source involved. “Our prototype is a proof-of-concept, so we designed it with an OLED array that is 10 pixels by 10 pixels; the resolution isn’t great,” added Franky So, co-corresponding author of the study appearing in ACS Applied Materials & Interfaces. “However, I can easily make it 500 pixels by 500 pixels, boosting the resolution substantially.” Source
