Available technologies, Electrical and Electronic components, Engineering, Information and communications technology (ICT), Medical devices, Medical Hardware, Signal and Data Processing, Telecommunication

ELECTROMECHANICALLY DAMPED RESONATOR DEVICES AND METHODS

Stopping the resonance of PMUTs using an electrostatic actuator, thereby reducing the amplitude of the displacement at the working frequency of more than 2 dB

The need and the challenge in novel PMUT architectures

  • Ultrasonic transducers are a type of acoustic sensor that can transmit and receive ultrasound signals. They are typically used in applications such as ultrasound imaging and non-destructive testing.
  • Ultrasonic sensing: a US$2 billion market in 2017, poised to reach around US$6 billion in 2023 (YOLE Development-July 2018)
  • Conventional ultrasonic transducers pose challenges in terms of efficiency, fabrication complexity and implementation costs. They are typically bulky and difficult to integrate
  • Piezoelectric micromachined ultrasonic transducers (PMUTs) generate sustained interest as a means to overcome these limitations. They are a low-cost and efficient alternative to conventional devices
  • PMUTs with high quality factors provide several advantages: They need lower activation voltage for the same acoustic power and provide less loss, but they are more sensitive to process variations and have a lower axial resolution because of their low bandwidth
  • Piezoelectric ultrasonic transducers are fabricated using bulk micromachining of SOI wafer (Silicon On Insulator). A trench is made into the bottom silicon layer to release the membrane using Reactive-ion etching (RIE process)
  • The challenge consists in reducing the influence of Reactive-ion etching (RIE) process variation on the resonant frequency and decreasing the ringing time

A novel technique to control the activation of piezoelectric micromachined ultrasonic transducers (PMUTs)

  • The goal of this technique is to dampen the displacement of the PMUT with electromechanical damping (actuators)
  • An anchoring technique is presented; it reduces the influence of process variations on the resonant frequency of PMUT devices
  • The top silicon layer is lithographically patterned to form a membrane inside a toroid of rectangular cross section both connected through several anchors of a given length. The toroid is fully anchored on the bottom silicon layer
  • A trench is etched in the bottom silicon layer to release the membrane using RIE process and therefore, the diameter of the trench is sensitive to the process variations
  • As a result, the width of the suspended part of the toroid will vary, but this variation will have little effect on the resonant frequency because it is mainly dominated by the diameter of the membrane and the length of the anchoring arms
  • Using anchoring arms in combination with a toroid mitigates the influence of process variation as compared to only using anchoring arms
  • A thin film of parylene is deposited on the top of the device to even better cancel the influence of process variations
  • The resonant frequency is dependent on the film thickness; it can be fine-tuned by varying the parylene thickness
  • The inclusion of actuators allows reducing the membrane deflection at the resonant frequency
  • Technology developed by Prof. Frédéric Nabki, Prof. Dominic Deslandes and Alexandre Robichaud (Department of Electrical Engineering, École de technologie supérieure (ÉTS)), and Prof. Paul Vahé Cicek (Department of Computer Engineering, UQAM University)

Advantages

  • Allowing for a drastic reduction in the resonant frequency sensitivity to process variations of high-quality factor PMUT in a simple and low-cost manner.
  • Allowing for the decrease of their ringing time in order to maximize axial resolution
  • Fabricating PMUT with a precise resonant frequency and a larger bandwidth
  • High stability to fabrication process variations
  • Low fabrication cost
  • Ability to stop resonance to improve power efficiency and axial imaging resolution
  • Precise frequency control is essential in building an array of PMUT for ultrasound imaging and non-destructive testing

Market applications

  • Medical ultrasound devices
  • Ultrasound non-destructive testing (NDT) systems

Business opportunity

  • Technology available for licensing
  • Provisional patent application filed

CONTACT

If you are interested by this technology, please contact :
Jean-Philippe Valois, Director Business Development, Engineering
JPValoisl@aligo.ca, (514) 5750425

UNIVERSITY

École de Technologie supérieure (ÉTS)

Main inventors

frederic_nabki

Frédéric Nabki, Professor, Electric Engineering Department

Prof. Nabki received the B.Eng. degree in Electrical Engineering with Honors from McGill University in 2003, where he graduated with distinction. In 2009, he completed a Ph.D. degree in Electrical Engineering at McGill University in RFIC and MEMS. From 2008 to 2016 he was a Professor in microelectronics engineering at UQAM. He is now an Associate Professor in the Department of Electrical Engineering of the École de technologie supérieure (ETS), a constituent of the University of Quebec. Nabki’s research interests include microelectromechanical systems (MEMS) and RF/analog microelectronics, the integrating of MEMS devices with CMOS phase-locked loops, ultra-wideband transceivers, and MEMS interface circuits

dominic

Dominic Deslandes, Professor, Electric Engineering Department

Prof. Deslandes received the B.Sc. degree in electrical engineering from the University of Sherbrooke, Sherbrooke, QC, Canada, in 1998, and the M.Sc. and Ph.D. degrees in electrical engineering from the Ecole Polytechnique de Montreal, QC, in 2001 and 2005, respectively. From 2006 to 2007, he was a Post-Doctoral Researcher with the University of Sherbrooke. From 2007 to 2016, he was a Professor with the University of Quebec, Montreal. In 2016, he joined the Ecole de Technologie Superieure, Montreal, where he is currently a Professor. His current research interests include the analysis, synthesis, and integration of passive components for millimeter-wave and Terahertz systems. Dr. Deslandes was a recipient of the Natural Sciences and Engineering Research Council Doctoral Prize in 2007 for the Best Engineering Thesis in Canada. Also, one of his papers has been recognized by the Essential Science Indicators as one of the most cited article in engineering

vah

Paul-Vahé Cicek, Assistant Professor, Computer Engineering Department

Prof. Cicek received his PhD degree in Electrical Engineering from McGill University (Montreal) in 2016 with a nomination to the ADESAQ Excellence Prize. Since 2009, he has been working as MEMS Engineering Lead and Manager of the microsystems division at MEMS Vision, a startup company he co-founded. In 2014, he was hired as Assistant Professor at Université du Québec à Montréal (UQAM), where he is exploring his research interests related to microtechnologies: MEMS, microfluidics, microelectronics, encapsulation, and their mutual integration