Anartz Unamuno 26-09-2013 - Smart system · PDF fileAnartz Unamuno I 26.09.2013 I slide 15...

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New applications for ultrasound technology through CMUTs

Anartz Unamuno

26-09-2013

© Fraunhofer IPMS

Anartz Unamuno I 26.09.2013 I slide 2

Agenda Capacitive Micromachined Ultrasonic Transducers (CMUT)

• What is ultrasound

• 1o1 ultrasound transducers

• Comparison Piezoelectric & CMUT

• History of CMUTs

• Challenges CMUT & IPMS

• Strengths, Weaknesses, Opportunities, Threads

• Initial results of IPMS CMUTs

• Current research for CMUT applications (worldwide)

• Conclusion

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What is ultrasound?

Sample applications:

Medical imaging

Non-destructive testing

Level sensors

Speed sensors

Etc… T.G. Leighton / Progress in Biophysics and Molecular Biology 93 (2007) 3–83

Images form Wikipedia search: Ultrasound

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1o1 -- Ultrasonic transducers

Oralkan O., 2002

Capacitve Micromachined Ultrasonic Transducer

Piezoelectric Transducer

Image form Wikipedia search: Piezoelectricity

Mechanical displacement generates US waves

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Advantages -- Piezoelectric & CMUTs transducers

Piezoelectric CMUT

Accepted technology CMOS integration

Reliability(*) Batch production – reduced cost

Output acoustic pressure(*) RoHS compatible

Tight parameter specification

High temp. capable (ca. 800 ºC)

Scalability (size, shape, array, 2D)

Axial resolution

(*) Two factors that need to be addressed on CMUTs

Solving these two, CMUTs should be a winning technology!

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History of CMUTs

Khuri-Yakub, http://www-kyg.stanford.edu/khuriyakub/opencms/en/research/cmuts/History/index.html

A MEMS device researched over the last 20 years

But no products on Euro nor US market using CMUTs yet!!

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Challenges of fabricating CMUTs matches Fraunhofer IPMS expertise

Many issues have been previously solved at IPMS

Requirement Fraunhofer IPMS has marketed product

Large arrays of MEMS elements with quasi-identical performance

High voltage drive for capacitive MEMS

Low noise amplifiers or receive side

Integration MEMS-CMOS

Material expertise (process control)

Testing capabilities

Infrastructure to access and service small-to-medium size customers

US system integration

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Testable CMUT devices

Work at IPMS -- Electrically testable 1D CMUT array

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Work at IPMS -- Electrical impedance measurement

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Resonance frequency spread, SD = 17 kHz (62 array elements)

Work at IPMS -- Resonance frequency distribution

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Applications – Harsh environment

Reference 1

High Temperature

High Pressure

1. Kupnik et Al., US patent 7,843,022 2. M.-C. Ho, M. Kupnik, K. K. Park, K. Eckhoff, and B. T. Khuri-Yakub, “Wide pressure range

operation of air-coupled CMUTs,” in Proc. IEEE Ultrasonics Symposium, pp. 93-96, 2012.

Reference 2

Reference 2

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Applications – Chemical sensors

Almira Ramanaviciene, Darius Virzonis, Gailius Vanagas and Arnas Ramanavicius, “Capacitive micromachined ultrasound transducer (cMUT) for immunosensor design“, Analyst, 2010, 135, 1531 DOI: 10.1039/c0an00104j

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Applications – Neural stimulation

1. Omer Naor et al, “Towards multifocal ultrasonic neural stimulation II: design considerations for an acoustic retinal prosthesis“, J. Neural Eng. 9 026006, 2012

2. Menz, Michael D - Oralkan, Omer - Khuri-Yakub, Pierre T - Baccus, Stephen A, “ Precise neural stimulation in the retina using focused ultrasound“, The Journal of neuroscience: the official journal of the Society for Neuroscience, Vol. 33, No. 10

Reference 1

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Conclusions

• CMUTs enable novel ultrasonic applications

• CMUTs should not be seen as a replacement for pezoelectric transducers, but they are the only option in some applications (e.g. High temp, large 2D array integration, etc.)

• Technology is reaching a mature state to be deployed to the markets.

• IPMS has one of the few fabrication facilities around the world, where it is possible to produce large MEMS arrays at tight tolerances.

• Several team around the Globe are developing clever applications to make use of the CMUT capabilities.

Anartz Unamuno 26-09-2013 - Smart system · PDF fileAnartz Unamuno I 26.09.2013 I slide 15...

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