The resonant MEMS lab focuses on advancing innovations in micro/nanomechanical resonator and resoswitch devices and integrated systems for ultra-low power sensing and signal processing applications.

  • MEMS Resoswitch Technology

The processes used for achieving the resoswitches include the CMOS-MEMS process platform and SOI process. The development of the resoswitch calls for comprehensive analytical modeling, robustness and sensitivity enhancement, and practical tasks such as the implementation of high bias voltage and hermetic packaging. Much of the work is underway…

  • Resoswitch-Enabled Zero-Quiescent Power Wake-Up Receivers

Integrating the resoswitch and back-end circuit on the CMOS-MEMS process platform to achieve a 125-kHz wake-up receiver with zero standby power suitable for passive keyless entry (PKE) applications.

  • C.-P. Tsai, Y.-Y. Liao, and W.-C. Li, “A 125-kHz CMOS-MEMS Resoswitch Embedded Zero Quiescent Power OOK/FSK Receiver,” Proc., 33rd IEEE Int. Conf. on Micro Electro Mechanical Systems (MEMS’20), Vancouver, Canada, Jan. 18-22, 2020.

  • Resoswitch Derived On-Chip Structural Surface Condition Monitoring

The contact surface condition directly affect the tapping response of the resoswitch. By comparing the tapping bandwidth, one could deduce whether the contact surface properties change. This study could enable the on-chip in situ surface monitoring technology.

  • W.-C. Li, C.-P. Tsai, H.-W. Wang, “Device and method for monitoring surface condition of contact surface of detected object,” US Patent Application, 17/113,109, Dec. 7th, 2020.
  • S.-C. Lu, C.-P. Tsai, Y.-C. Huang, W.-R. Du, and W.-C. Li, “Surface Condition Influence on the Nonlinear Response of MEMS CC-Beam Resoswitches,” IEEE Electron Device Letters (EDL), vol. 39, no. 10, pp. 1600-1603, Oct. 2018.
  • S.-C. Lu, W.-R. Du, Y.-C. Huang, C.-P. Tsai, and W.-C. Li, “MEMS surface coating condition monitoring via nonlinear tapping of resoswitches,” Proc., 2018 IEEE Int. Frequency Control Symposium (IFCS’18), Olympic Valley, CA, May 21-24, 2018. (Student Best Paper Finalist)

  • Technologies for CMOS-MEMS Based Resonant Devices

The CMOS-MEMS process platform offers abundant combinations in achieving resonant devices. Some important techniques developed including temperature compensation and release yield improvement will eventually be applied to the CMOS-MEMS resoswitch technology.

    • Temperature compensation via electrical frequency pulling
    • Wet release yield improvement
  • C.-E. Hsu and W.-C. Li, “Enhancing the Release Process Yield for CMOS-MEMS Metal Resonators Based on Diffusion-Controlling Structures,” Proc., 34th IEEE Int. Conf. on Micro Electro Mechanical Systems (MEMS’21), Virtual Conference, Jan. 25-29, 2021.
  • C.-E. Hsu and W.-C. Li, “Mitigating the Insufficient Etching Selectivity in the Wet Release Process of CMOS-MEMS Metal Resonators via Diffusion Control,” IEEE J. Microelectromech. Syst. Lett. (JMEMS Letters), vol. 29, no. 6, pp. 1415-1417, Dec. 2020. (Highlighted as JMEMS RightNow Paper)
  • J.-R. Liu and W.-C. Li, “Temperature-compensated CMOS-MEMS resonators via electrical stiffness frequency pulling,” J. Micromech. Microeng. (JMM), vol. 30, no. 1, pp. 014002, Nov. 2019. (in the special issue of JMM Emerging Leaders)
  • J.-R. Liu and W.-C. Li, “A Temperature-Insensitive CMOS-MEMS Resonator Utilizing Electrical Stiffness Compensation,” Proc., 32nd IEEE Int. Conf. on Micro Electro Mechanical Systems (MEMS’19), Seoul, South Korea, Jan. 27-31, 2019, pp. 161-164.

  • Cutting Force Sensors & Tool Wear Monitoring

Developing affordable cutting force sensors for real-time condition monitoring of manufacturing tools. The obtained captured data then are used for training and establishing an inference model for tool wear.

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