Scandium-Doped Aluminum Nitride PMUT Arrays for Wireless Ultrasonic Powering of Implantables

Herrera, Bernard; Simeoni, Pietro; Giribaldi, Gabriel; Colombo, Luca; Rinaldi, Matteo

doi:10.1109/ojuffc.2022.3221708

Cited by 6 publications

(2 citation statements)

References 31 publications

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“…Moreover, both AlScN and AlN are CMOS compatible, which is more convenient in integration with circuits toward miniaturization [ 4 ]. PMUTs have many applications in the gas and fluid domains: in-air range detection [ 5 , 6 ], MEMS hydrophone [ 7 ], underwater communication [ 8 ], underwater wireless power supply [ 9 ], ultrasonic flowmeter [ 10 ], Doppler blood flowmeter [ 11 ], and fingerprint sensor [ 12 , 13 , 14 ]. Several studies on utilizing PMUTs for solid internal inspection have been conducted.…”

Section: Introductionmentioning

confidence: 99%

A Novel Nondestructive Testing Probe Using AlN-Based Piezoelectric Micromachined Ultrasonic Transducers (PMUTs)

Yin,

Zhou,

Lou

2024

Micromachines

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Ultrasonic nondestructive testing (NDT) usually utilizes conventional bulk piezoelectric transducers as transceivers. However, the complicated preparation and assembly process of bulk piezoelectric ceramics limits the development of NDT probes toward miniaturization and high frequency. In this paper, a 4.4 mm × 4.4 mm aluminum nitride (AlN) piezoelectric micromachined ultrasonic transducer (PMUT) array is designed, fabricated, characterized, and packaged for ultrasonic pulse–echo NDT of solids for the first time. The PMUT array is prepared based on the cavity silicon-on-insulator (CSOI) process and packaged using polyurethane (PU) material with acoustic properties similar to water. The fabricated PMUT array resonates at 2.183 MHz in air and at around 1.25 MHz after PU encapsulation. The bandwidth of the packaged PMUT receiver (244 kHz) is wider than that of a bulk piezoelectric transducer (179 kHz), which is good for axis resolution improvement. In this work, a hybrid ultrasonic NDT probe is designed using two packaged PMUT receivers and one 1.25 MHz bulk transmitter. The bulk transmitter radiates an ultrasonic wave into the sample, and the defect echo is received by two PMUT receivers. The 2D position of the defect could be figured out by time-of-flight (TOF) difference, and a 30 mm × 65 mm detection area is acquired. This work demonstrates the feasibility of applying AlN PMUTs to ultrasonic NDT of solids and paves the way toward a miniaturized NDT probe using AlN PMUT technology.

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Section: Introductionmentioning

confidence: 99%

A Novel Nondestructive Testing Probe Using AlN-Based Piezoelectric Micromachined Ultrasonic Transducers (PMUTs)

Yin,

Zhou,

Lou

2024

Micromachines

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“…Leveraging the Scandium-doped AlN deposition capabilities developed, the power transfer performance of PMUT arrays based on this materials were studied. Matching networks, for maximizing the voltage output, load optimization as well as efficiency considerations were taken into account [51,52].…”

Section: Alscn Power Transfermentioning

confidence: 99%

Ferroelectric micro-machined ultrasonic transducers for biomedical and processing-in-sensor applications

Soukup¹

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Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) are Micro Electro-Mechanical Systems (MEMS) devices that have become an established technology in applications such as rangefinding, fingerprint sensing and imaging due to their capability of ultrasonic transduction in a miniaturized footprint, easily amenable to create large arrays. However, their application space still remains quite open. PMUTs are well fitted to applications in liquid media, such as implantable and underwater devices, due to their inherent acoustic matching and wide bandwidth. Thus, in the first part of this dissertation, novel applications are explored such as PMUT-based intra-body networking, power transfer, source localization, wide-band matching and duplexing.Aluminum Nitride (AlN) has been the piezoelectric material of choice for PMUts in a good part of the work due to its biocompatibility and possibility of single-chip integration with supporting CMOS circuitry. However, Scandium doping of AlN thin films has recently been demonstrated to increase piezoelectric coupling coefficients while introducing ferroelectric properties in the material. However, a simultaneous use of both capabilities has not been demonstrated in the state-of-the-art. The ability of having distinct ferroelectric states, that alter the mechanical performance of the devices, allows for Processing In-Sensor (PIS) with concurrent actuation features and provides the building blocks for analog computing and neuromorphic signal processing capabilities. The second part of the dissertation thus explores the AlScN material integration into novel Ferroelectric Micromachined Ultrasonic Transducers (FMUTs) and their emerging application space.

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An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants

Rashidi,

Saccher,

Karuthedath

et al. 2023

2023 IEEE International Ultrasonics Symposium (IUS)

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Aluminum Nitride (AlN) Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) are gaining interest for biomedical implant power due to biocompatibility and lowtemperature processing. However, due to the low piezoelectric coefficient of AlN PMUTs, storage capacitors are often used to accumulate ultrasonic power transferred over an extended time. The accumulated energy is then used to power a DC load, which leads to a long start-up time, and insufficient duty cycle for some applications. We present an ultrasonically powered system for biomedical implants capable of delivering mW-range instantaneous power to DC loads, without pre-storing it. The system features a 25 mm 2 AlN PMUT, an inductive matching network, and an application-specific power management integrated circuit(ASIC). For an acoustic intensity of 360 mW/cm 2 at the surface of the PMUT, an open-circuit voltage of 1.11 V and an aperture efficiency of 30.5 % are measured. Furthermore, by connecting a series-matching inductor to the PMUT, the highest-reported power delivered to the load (PDL) of 6.4 mW is measured over an optimal load of 7.6 Ω. Finally, together with the ASIC and at the intensity of 108 mW/cm 2 , our system delivers 1.04 mW DC power to a 3.3 kΩ load, which is over two orders of magnitude higher than the previously reported average DC power for AlN PMUTs.

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Scandium-Doped Aluminum Nitride PMUT Arrays for Wireless Ultrasonic Powering of Implantables

Cited by 6 publications

References 31 publications

A Novel Nondestructive Testing Probe Using AlN-Based Piezoelectric Micromachined Ultrasonic Transducers (PMUTs)

A Novel Nondestructive Testing Probe Using AlN-Based Piezoelectric Micromachined Ultrasonic Transducers (PMUTs)

Ferroelectric micro-machined ultrasonic transducers for biomedical and processing-in-sensor applications

An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants

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