CAAV Talk by Associate Professor Joshua Lee
Harnessing vibrations at the microscale in semiconductor microchips
Title: Harnessing vibrations at the microscale in semiconductor microchips
Speaker Biography: Associate Professor Joshua Lee recently joined UTS in the School of Electrical & Data Engineering. Prior to his arrival in Australia, he was Principal Scientist at the Institute of Microelectronics (IME), A*STAR, Singapore (from Nov 2020), where he led projects with a focus on piezoelectric MEMS that harness acoustic waves for ultrasonic imaging & sensing, wireless power delivery, lab-on-chip cell/particle actuation, next-gen fast computation, passive wireless sensors for environmental monitoring, as well as chip-scale devices for ultra-low power event-driven sensing and IoTs. From 2009-2020, he was an Associate Professor the Department of Electrical Engineering, City University of Hong Kong, during which his research evolved from silicon MEMS to piezoelectric MEMS. He was awarded a visiting professorship by Université Grenoble Alpes in 2017 to collaborate on MEMS microphones and transducers. He received all his degrees (BA & MEng in 2005, and PhD in 2009) from the University of Cambridge.
Abstract: Are there interesting problems or applications that tap into vibrations at the microscale? Microelectromechanical systems (MEMS) resonators are vibratory mechanical devices interfaced electrically, fabricated in semiconductor processes. This talk begins with the basics of traditional silicon MEMS resonators, highlighting key bottlenecks with the aim to explain the motivation for the shift to piezoelectric MEMS. The rest of the talk aims to illustrate how piezoelectric MEMS provides a rich and versatile toolbox to explore various applications based on the piezoelectric MEMS resonator. Beginning first with UHF band frequency references, the talk will then show how these can be configured as chip-scale magnetometers towards realizing all-mechanical 10-DOF inertial measurement units (IMUs). We then move to show how the strong electro-mechanical conversion in the piezoelectric can be capitalized to work the device in a fluid environment for sensing. But then how do you dextrously bring particles in a fluid to the device and without damaging biological matter? This is addressed by recent attempts to combine acoustic manipulation techniques to piezoelectric MEMS resonators. To show the critical role of piezoelectric materials innovation on device capabilities, recent results of sputtered PZT for micro-ultrasonic transducers producing high transmit-receive sensitivity in immersion are discussed. While the above examples all involve generating vibrations from the chip, the final case study describes zero-power acceleration sensor-switches. These are event-aware MEMS sensors that draw virtually no power until an irregular “shake-up” is detected, waking up the wireless sensor node that transmits data to a remote located central control.
