The bright future of MEMS ultrasonic solutions – Interview of Chirp Microsystems, a TDK group company

Thanks to new applications, especially in the consumer and medical markets, the ultrasound modules market will boom in the next five years. It is expected to grow from a US$2 billion market in 2017 to US$6 billion in 2023, with a CAGR2017-2023 of 18%.

From a technology perspective, the ultrasound modules market is today almost exclusively comprised of bulk piezoelectric transducers. In their new report Ultrasound Sensing Technologies for Medical, Industrial and Consumer Applications, Yole Développement explains how the ultrasonic transducer ecosystem may evolve, and how Micro-machined ultrasound transducer (MUT) technologies will rapidly penetrate the ultrasound market. Miniaturization, low cost, and integration are major drivers for ultrasonic transducers, which explains the popularity of new technologies coming from the semiconductor industry.


Yole’s analysts recently had the opportunity to interview Michelle Kiang, Chief Executive Officer and Co-Founder of Chirp Microsystems, one of the key ultrasonic sensor players, which has developed an innovative technology based on PMUT. She agreed to share her vision of the ultrasonic sensor market. Marjorie Villien, Technology & Market Analyst specialised in Medical Imaging & Biophotonics and Alexis Debray, Technology & Market Analyst specialized in Optoelectronics, worked together to produce the report and conduct this interview.

Note: Chirp Microsystems’ solution will be available for review and discussions at the 2018 TDK Developers Conference. This event, powered by TDK, takes place in Santa Clara, California, on September 17&18. Full program & registration : Here.

Yole Développement: Could you briefly introduce Chirp Microsystems (Chirp) and its history?

Michelle Kiang: Chirp was founded in 2013 based on pioneering research and IP developed at the University of California’s Berkeley Sensor and Actuator Center (BSAC). The founding team developed the world’s first MEMS-based ultrasonic time-of-flight (ToF) sensor, the CH-101, which we unveiled at the 2016 Consumer Electronics Show (CES). We later developed a second ToF sensor, CH-201, that provides longer range (5m), room-scale sensing to meet customer requirements for robotics, drones, and IoT products. In parallel, we developed a complete solution combining software and hardware to enable high-accuracy, extremely low-power, inside-out 6-DOF controller tracking for VR/AR/MR systems, which we demonstrated at CES 2017. Along the way, we built a world-class supply chain to enable us to ship ultrasonic ToF sensors for high-volume consumer electronics applications. In early 2018, the company was acquired by TDK and became a new part of TDK’s Sensor System Business Company, along with other familiar names in the MEMS industry including InvenSense, ICSense, EPCOS, and Tronics.

 Chirps piezoelectric micromachined ultrasonic transceiver yole sept2018 small

Chirp’s piezoelectric micromachined ultrasonic transceiver
(Source: Chirp)

YD: Chirp’s technology is based on PMUT. Please introduce this technology and tell us its advantages over competitive technologies?

MK: Ultrasonic ToF sensors are widely used in automotive and industrial applications because they provide the best range sensing performance in many different environments. Chirp is the first company to introduce an ultrasonic sensor based on a micromachined ultrasonic transducer (MUT). We chose piezoelectric MUTs (PMUTs) because we are targeting operation in air, where large vibration amplitude is required. CMUTs operating in air require large capacitive gaps and therefore high voltage (typically exceeding 100V), whereas PMUTs are capable of low-voltage operation. In the market today, we typically see comparison with infrared (IR) ToF sensors. Relative to IR ToF, ultrasonic ToF has the advantage that it can work in direct sunlight, has much lower power consumption (10’s of microwatts for ultrasonic ToF versus 10’s of milliwatts for IR ToF), and can cover a field-of-view up to 180 degrees with a single sensor, which is important for many different products in a variety of markets such as smart home, mobile, wearable, and robotics.

Chirp’s piezoelectric MEMS ultrasonic transducers offer long range and low power sensing capabilities in a micro-scale package, enabling products to accurately perceive absolute position in the three-dimensional world in which we live. Combined with Chirp’s embedded software library, these sensors advance user experiences with VR/AR, mobile, wearables, robotics, drones and occupancy detection.


YD: At Yole Développement, we see a bright future for CMUT and PMUT technologies coming from new applications of ultrasonic sensing in the consumer (fingerprint sensing) and in the medical (handheld systems) markets. What are Chirp’s current developments and applications in these and other markets?

MK: Currently, Chirp is focused on ultrasonic ToF sensors operating in air, or “air-coupled” ultrasonic sensors for consumer electronic applications. While our transducer technology may have applications outside the consumer space, we are very busy addressing the many applications that our customers have found for ToF sensors. In the meantime, InvenSense is developing fingerprint sensors using PMUT technology also originated from the same research team at UC.


YD: Chirp Microsystems was acquired by TDK earlier this year. In your opinion, what will be the impact on Chirp Microsystems of this integration into TDK?

MK: We decided to join TDK because we saw tremendous synergy with TDK’s piezoelectric materials and conventional ultrasonic transducer technology, the MEMS sensor product lines such as motion and microphone, and their core competence in sensor fusion software. Post-acquisition, we have accelerated our ramp to mass production through integrating our back-end and supply-chain operations, leveraging TDK’s deep experience and extensive sales channels in bringing quality components to the mass market.

 Chirp sensor pencil yole sept2018Chirp’s piezoelectric micromachined ultrasonic transceiver
(Source: Chirp)

YD: Could you tell us about future applications for Chirp devices?

MK: We have a product road-map that will see the introduction of new sensors with longer sensing range, smaller form-factor, and more on-chip signal processing capabilities. We are already engaged with customers in diverse applications such as VR/AR, smart-home/speaker, drone, robotics, and mobile computing devices.


YD: How do you envisage the ultrasonic market in a few years?

MK: We expect that many users of IR ToF sensors and conventional ultrasonic sensors will choose Chirp’s MEMS-based ultrasonic ToF sensors. Outside of ToF sensing, there’s a lot of interesting activity in the ultrasound space, from haptics you can feel in the air to parametric audio for directional speakers. The ultrasound band is an unregulated spectrum and there’s not too many people using it today. We see a lot of opportunities to leverage the ultrasonic spectrum for new applications.


YD: Could Chirp’s technology be used for applications other than ultrasound?

MK: Broadly speaking, we make piezoelectric MEMS for acoustic devices, so the fundamental technology could be applied to many other acoustic applications. However, we have seen tremendous interest in the capabilities of our ultrasonic product line, so we haven’t spent a lot of time investigating applications outside of ultrasound so far.


YD: Anything you would like to add for your readers?

MK: Chirp is the first “MEMS 2.0” company to be founded after the fabless MEMS pioneers like InvenSense and SiTime started over a decade ago. With the high level of maturity of the global MEMS supply chain, we think the time is ripe for many other MEMS companies to follow our capital-efficient model and introduce new products into the market.




headshot mhkiang round yole sept2018

Michelle Kiang is the CEO and co-founder of Chirp Microsystems, Inc., a company commercializing an ultra-low power, ultrasonic 3D sensing technology that will revolutionize human machine interfaces for IoT devices. Chirp was acquired in February 2018 by TDK as a wholly own subsidiary and a new business unit under their MEMS Sensor Business Group. Most recently, she led corporate business development at NeoPhotonics (NPTN), managing M&A, strategic investment, and partnership activities. Previously, she was the Director of Strategy and Planning for the Image Sensor Group at Micron Technology (MU). Her prior startup experience included as the co-founder and VP Marketing for PINC Solutions, a leading provider of sensor-fusion enabled real-time visibility solutions, and Onix Microsystems, a pioneer in MEMS-based optical networking products. Dr. Kiang received the M.S. and Ph.D. degrees (with Honor) from University of California, Berkeley, and the B.S. degree from National Taiwan University, all in Electrical Engineering.



Photo MarjorieVillien YOLE 2018

As a Technology & Market Analyst, Medical Imaging & Biophotonics, Dr. Marjorie Villien is member of the Life Sciences & Healthcare division at Yole Développement. She is a daily contributor to the development of medical technologies activities with a dedicated collection of market & technology reports as well as custom consulting projects. As an example, Marjorie was involved in a project focused on videoscopy for endoscopy application, to understand the benefits of the CCD/CMOS solution and identify business opportunities. In parallel, she performed an analysis of the PET detectors technology to evaluate the impact of innovative Solid-State technologies on the evolution of the nuclear medicine industry. After spending two years at Harvard, Marjorie served as a research scientist at INSERM in the field of medical imaging for the treatment of Alzheimer’s disease, stroke and cancers. She has spoken in numerous international conferences and has authored or co-authored 11 papers and 1 patent. Marjorie is daily exchanging with clinicians, researchers and industrial partners to understand technology issues and ensure the connection between R&D and applications. Marjorie Villien graduated from Grenoble INP and holds a PhD in physics & medical imaging.


Photo AlexisDebray YOLE 2018

Dr. Alexis Debray is a Technology & Market Analyst, Optoelectronics at Yole Développement (Yole). As a member of the Photonics, Sensing & Display division, Alexis is today engaged in the development of technology & market reports as well as the production of custom consulting projects dedicated to the imaging industry. After spending 2 years at the University of Tokyo to develop an expertise focused on MEMS technologies, Alexis served as a research engineer at Canon Inc. During 15 years he contributed to numerous projects of development, focused on MEMS devices, lingual prehension, and terahertz imaging devices. Alexis is the author of various scientific publications and patents. He graduated from ENSICAEN and holds a PhD in applied acoustics.



 Sources: tdk.invensense logo yole sept2018  – chirplogo yole sept2018 –  logo yole petit



couv ultrasound

Ultrasound Sensing Technologies for Medical, Industrial and Consumer Applications

New applications along with manufacturing capabilities and technological readiness are driving the takeoff of micro-machined ultrasonic transducers. – Get more