Ultrasound transducers have traditionally produced sound waves by utilizing piezoelectric crystal technology. Although piezoelectricity has proven effective for ultrasound, it presents limitations due to high production costs and size requirements. Chip-based transducers, or micromachined ultrasound transducers (MUTs), that use silicon chips to convert voltage to resonance, have emerged as promising alternatives to piezoelectric crystal transducers.
Ultrasound manufacturers seek alternatives to conventional transducers
Ultrasound transducers have traditionally produced sound waves by utilizing piezoelectric crystal technology. Although piezoelectricity has proven effective for ultrasound, it presents limitations due to high production costs and size requirements. Chip-based transducers, or micromachined ultrasound transducers (MUTs), that use silicon chips to convert voltage to resonance, have emerged as promising alternatives to piezoelectric crystal transducers. Chip-based transducers are more affordable than conventional transducers because silicon is less expensive than piezo crystals and silicon chips can be batch-produced, while piezoelectric transducers require more intensive manufacturing. Chip-based transducers are also advantageous because they can handle higher frequencies than piezoelectric transducers and they can be easily integrated into electronics, making them ideal for 3D imaging and full-body scanning.
The first launch of chip-based transducers was lackluster
Hitachi introduced the first chip-based ultrasound transducer, a capacitive micromachine ultrasound transducer (CMUT), in 2009 with the MATRIX linear transducer 4G CMUT. Despite initial interest, production did not expand as quickly as many expected due to image quality and production challenges. In the transition to a silicon chip, the transducer lost penetration capabilities. Although the transducer could scan the entire body, it was limited to scanning at a single depth, which was inferior to specialized piezoelectric transducers and insufficient for several medical procedures. Additionally, since the technology was new, manufacturing processes had not been developed to mass-produce the transducers. If these issues were resolved, end-users could have purchased a single, low-cost transducer instead of multiple transducers with different scanning frequencies. However, until recently, ultrasound manufacturers were hesitant to develop chip-based ultrasound equipment following the 4G CMUT’s difficult launch.
Chip-based transducers have returned and are here to stay
Although excitement from their initial product launch has waned, Butterfly Network likely put chip-based ultrasound development back on track with their launch of the Butterfly iQ in 2018. The Butterfly iQ is the first complete ultrasound-on-a-chip system. It is intended for whole-body use and sold at the low price of $1,999, compared to the global average selling price of $8,200 for handheld systems. While some industry experts think this product has ushered in a new ultrasound era, others are less enthusiastic. They cite the chip-based transducers’ lower image quality compared to premium ultrasound systems as the main reason why this technology will not revolutionize the ultrasound market. Time will tell which camp is correct, but the Butterfly iQ certainly primed the market for several ultrasound start-ups to launch innovative transducers. Kolo Medical launched the chip based SiliconWave transducer at the end of 2017, and in August 2019, Exo Imaging announced their plans for a piezoelectric micromachine ultrasound transducer (PMUT) after raising $35 million in funding. This transducer will pair with Exo Imaging’s advanced artificial intelligence platform. (Source: Exo Imaging).
Ultrasound giants race to embrace chip-based ultrasound
Behind the scenes, medical imaging manufacturers are racing to produce chip-based ultrasound systems that can be mass produced and miniaturized. Large manufacturers are leveraging their partnerships with semiconductor businesses to bring these products to market within the next five years. Semiconductor manufacturers will play a vital role in the development of these systems through collaborations, such as the partnership between STMicroelectronics and medical device manufacturer MU.
Chip-based ultrasound could drastically expand market adoption
Major medical imaging manufacturers launching chip-based ultrasound systems will have a dramatic impact on the medical imaging market. Their access to the healthcare industry and ability to produce enormous volumes of equipment could create a major change in the global ultrasound market. In the long-term, lack of image quality will prevent chip-based systems from replacing conventional ultrasound systems that utilize piezoelectric transducers in traditional settings. However, chip-based ultrasound manufacturers will likely target new, unconventional ultrasound markets, where their systems will be used for primary evaluations which do not require impeccable image quality. Historically, primarily hospitals and medical imaging clinics have purchased ultrasound equipment, but if ultrasound drastically drops in price it could become common in physicians' offices, health clinics, and point-of-care settings, and eventually evolve into a consumer product.
The future of chip-based ultrasound is more expansive than the traditional market
Beyond their impact on the traditional diagnostic ultrasound market, chip-based ultrasound systems could enable and improve unconventional procedures. Chip-based ultrasound systems are strong candidates for superior high-intensity focused ultrasound (HIFU), an early-stage technology to combat chronic illness by using sound waves to destroy diseased tissue. Additionally, chip-based ultrasound systems can be extremely miniaturized and placed on catheters or integrated into wearable patches. There is little doubt that semiconductor chips will change the ultrasound landscape. The real question is who will lead the charge.