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Steve Shen

Faculty Photo

Mechanical Engineering

  • (206) 543-5718
  • MEB 313


  • Ph.D., University of California, Berkeley, 1991
  • M.S., National Taiwan University, Taipei, 1986
  • B.S., National Taiwan University, Taipei, 1981

Research Statement

Professor Shen's research areas are vibration and dynamics with a special focus on (1) medical and dental devices, (2) PZT thin-films sensors/actuators, (3) advanced manufacturing, (4) autonomous flying vehicles, (5) high-speed precision machinery, and (6) sports equipment.  His research has been a synergistic collaboration with brilliant researchers from material science, medicine, dentistry, biology, and bio-mechanics from academia and industry.

In the area of medical and dental devices, his research team designs and develops (a) introcochlear acoustic microacutators for hybrid cochlear implants, (b) introcochlear microphones for totally implantable cochlear prostheses, (c) diagnostic tools to evaluate stability of dental implants, and (d) futuristic ultrasound devices.  Professor Shen not only studies the dynamics of these medical and dental devices, but also instruments these devices with calibrated experiments.  For example, his research team analyzed and measured vibration of intracochlear microactuators in aqueous environments.  Moreover, acute animal tests were performed to prove the concept of the intracochlear microactuators. 

In the area of PZT thin-film devices, his research team designs, develops, and evaluates PZT thin-film sensors/actuators fabricated on silicon substrate and polymeric substrate.  The PZT on silicon substrate is in the form of a homogeneous PZT thin film.  The homogeneous PZT thin film is sol-gel derived, and the thin-film sensors or actuators are fabricated in clean rooms.  A sample application is intracochlear microactuators for hybrid cochlear implants.  The PZT on polymeric substrate is in the form of PZT-silane nanocomposite thin films.  The PZT-silane composite thin films are fabricated via various methods, such as 3-D printing, ink-jet printing, spin coating, and drop casting.  A sample application is structural health monitoring sensors for composite aircraft panels.  To optimize sensor/actuator design, finite element analyses are routinely conducted through use of ANSYS.  Performance of the fabricated sensor/actuators is evaluated via calibrated experiments.  Procedures have been developed to assess piezoelectric constants and residual stresses of PZT thin films.  Nonlinear dynamics of PZT thin-film sensors/actuators, such as snap-through phenomena, is also studied.

In the area of advanced manufacturing, Dr. Shen has created new recipes and processes in additive manufacturing, nano-manufacturing, and clean room manufacturing to advance PZT thin-film technologies.   For nano-manufacturing, his research team has created advanced recipes to fabricate PZT nano-particles by controlling ramping and cooling rates.  For additive manufacturing, his team has developed special ink in the form of PZT nano-particles suspended in ethanol that can be printed to deposit PZT-silane nano-composite films.  His team also integrates inkjet printing of silver electrodes and deposition of PZT-silane films to form functional sensor/actuator systems.  For clean room manufacturing, his research team has created recipes to etch platinum and PZT, enabling sophisticated PZT thin-film devices fabricated on silicon substrate.

In the area of autonomous flying vehicles, his research objectives are (a) to dynamically model the complicated mechanisms crucial for highly versatile insect flight, (b) to use the models to advance design of micro-aerial vehicles (MAV), (c) to develop key sensors and actuators for better steering and control of MAV, and (d) to advance dynamics and control of high-payload, high-endurance drones.  For example, his research team has developed and validated an inertial-elastic model of the insect forewing in air and in vacuum (and also won a best paper award).  Moreover, his research team has concluded that modest changes in stroke deviation can significantly affect steering. Both aerodynamic and inertial torques are critical to maneuverability, while the former dominates in steady-state flights and the latter is significant during short transients.  

In the area of high-speed precision machinery, Professor Shen has developed computational algorithms to predict vibration and understand the physics of complex rotating machines, such as (a) hard disk drives (HDD), (b) cyclic symmetric rotors (e.g., turbines), (c) mistuned rotors, and (d) dental and surgical drills.  For HDD, his research focuses on spindle vibration, fluid-dynamics bearing technologies, actuators, suspensions, and heads.  For cyclic symmetric rotors, he studies interaction between the spinning rotor and a stationary housing via multiple bearing supports.  For mistuned rotors, he studies formation of mode localization phenomena and how presence of bearings and housing affects mode localization.

In the area of sports equipment, Dr. Shen studies safety of alpine touring ski boots and bindings by investigating their release process and mechanical design.

More about Professor Shen's research

Select publications

  1. N. Khouja, W. C. Tai, I. Y. Shen, J. A. Sorensen, 2019: “A critique of resonance frequency analysis and a novel method for quantifying dental implant stability in vitro,” International Journal of Oral & Maxillofacial Implants, Vol. 34(3), pp. 595-603.
  2. Yifeng Liu, Chuan Luo, G. Z. Cao, Clifford R. Hume, I. Y. Shen, 2018: “A Study on Long-Term In Vitro Reliability of Intracochlear PZT Microactuators,” ASME Journal of Engineering and Science in Medical Diagnostics and Therapy, Vol. 1, pp. 031005-1 to 031005-8, doi: 10.1115/1.4040103.
  3. M. Jankauski, T. Daniel, I. Y. Shen, 2017: “Asymmetries in Wing Inertial and Aerodynamic Torques Contribute to Steering in Flying Insects,” Bioinspiration & Biomimetics, vol. 12(4), Article Number: 046001.
  4. M. Jankauski and I. Y. Shen, 2016: Experimental Studies of an Inertial-Elastic Rotating Wing in Air and Vacuum, International Journal of Micro Air Vehicles, vol. 8, pp. 53-63.
  5. Weiwei Xu, Hsien-Lin Huang, Yifeng Liu, Chuan Luo, G. Z. Cao, I.Y Shen, 2016, “Fabrication and Characterization of PZT-Silane Nano-Composite Thin-Film Sensors,” Sensors and Actuators A—Physical, vol. 246, pp. 102-113.
  6. Chuan Luo, Irina Omelchenko, Robert Manson, Carol Robbins, Elizabeth C. Oesterle, G. Z. Cao, I. Y. Shen, Clifford R. Hume, 2015 “Direct Intracochlear Acoustic Stimulation using a PZT Microactuator,” Trends in Hearing, Vol. 19, pp.1-14.
  7. W. C. Tai, and I. Y. Shen, 2015: Ground-Based Response of a Spinning, Cyclic Symmetric Rotor Assembled to a Flexible Stationary Housing via Multiple Bearings. ASME Journal of Vibration and Acoustics, Vol. 137, pp. 041011-1 to 041011-12.
  8. Y. F. Chen and I. Y. Shen, 2015: Mathematical Insights of Mode Localization in Nearly Cyclic Symmetric Rotors with Mistune, ASME Journal of Vibration and Acoustics, Vol. 137, pp. 041007-1 to 041007-13.
  9. Hsien-Lin Huang, G. Z. Cao, and I. Y. Shen, 2014: Hydrothermal Synthesis of Lead Zirconate Titanate (PZT) Nano-Particles Using Controlled Ramping and Cooling Rates. Sensors and Actuators A—Physical, Vol. 214, pp. 111-119.
  10. Chuan Luo, G. Z. Cao, and I. Y. Shen, 2013: Development of a Lead-Zirconate-Titanate (PZT) Thin-Film Microactuator Probe for Intracochlear Applications. Sensors and Actuators A—Physical, Vol. 201, pp. 1-9.
  11. I. Y. Shen, Liu Mengjun, Gao Feng, Lee Chong Wee, Lin Wuzhong, and Ong Eng Hong, 2013: Extraction of Bearing Coefficients of Fluid-Dynamic Bearing Spindle Motors Using a Proof Mass and a Hammer—A Refined Approach. IEEE Transaction of Magnetics, Vol. 40, pp. 2755-2761.
  12. Q. Guo, G. Z. Cao, and I. Y. Shen, 2013: Measurements of Piezoelectric Coefficient d33 of Lead Zirconate Titanate (PZT) Thin Films Using a Mini Force Hammer. ASME Journal of Vibration and Acoustics, Vol. 135, paper 011003.
  13. Tsung-Liang Wu and I. Y. Shen, 2009: Position Error Predictions of a Hard Disk Drive Undergoing a Large Seeking Motion with Shock Excitations, IEEE Transaction of Magnetics, Vol. 45, pp. 5156-5161.
  14. Hyunchul Kim, Nicholas T. K. Colonnese, and I. Y. Shen, 2009: Mode Evolution of Cyclic Symmetric Rotors Assembled to Flexible Bearings and Housing. ASME Journal of Vibration and Acoustics, pp. 051008, 1-9.

Honors & awards

  • N. O. Myklestad Award, American Society of Mechanical Engineers, 2017
  • Best Paper Award, International Micro Air Vehicle Conference and Competition, Delft, The Netherlands, August 12-15, 2014
  • Valued Reviewer, Sensors and Actuators A – Physical, 2009
  • Distinguished Guest, Data Storage Institute, Singapore, 2007
  • ME Outstanding Faculty of the Year Award, 1998, 2003, 2004
  • IBM Partnership Award, 1998
  • ASME Fellow, 2007