However, growth is set to resume with 13 percent growth in 2021 and over the period 2019 to 2025 the market will show a 5.1 percent compound annual growth rate, according to Yole Developpement. In 2025 the market will be worth $6.2 billion.
The biggest market segment will be automotive driver assistance systems (ADAS) – expected to be $4.3 billion of the overall market and based on established piezoelectric transducer technologies. Meanwhile consumer and medical applications will start to use capacitive micromachined ultrasonic transducers (CMUTs) and piezoelectric micromachined ultrasonice transducers (PMUTs) and grow at twice the rate.
The ultrasound sensing modules market 2019 to 2025 by application. Source: Yole Developpement.
In the automotive sector, players like Continental are participating in projects to integrate MUT technologies for in-cabin gesture recognition. Today Qualcomm and TDK Chirp are offering off-the shelf solutions or platforms. Emerging ultrasound technologies not only compete with standard piezoelectric bulk technologies, but also with other types of detection such as 3D sensing and radar technologies.
Among the newer opportunities for CMUT and PMUT are the integration of ultrasound modules in virtual reality headsets for gesture-recognition applications, fingerprint biometrics for smartphones and tablets in the consumer market, and point-of-care ultrasound in the medical sector.
CMUT and PMUT sensors have differing attributes. CMUT allows excellent image resolution, which makes them candidates for medical imaging applications. PMUT are more suited to detection which allows them to be integrated into applications such as biometric fingerprint and time-of-flight applications in the air for gesture recognition.
The two principle choices for PMUT manufacture are piezoelectric layers of aluminum nitride AlN or lead zirconate titanate (PZT). While AlN is compatible with cleanroom environments, PZT is more difficult to use, often requiring the use of foundries that have adapted to this manufacturing process.
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