Towards Sensor Integration Using CMOS MEMS Platform
Weileun Fang
Department of Power Mechanical Engineering, and NEMS Institute, National Tsing Hua University, Taiwan

The CMOS MEMS process has the advantage of monolithic integration of the IC and micro mechanical components. In addition, the mature CMOS fabrication processes are available in many IC foundries. Thus, the CMOS-based micro fabrication technology provides a promising approach to implement MEMS devices. Presently, various CMOS-based MEMS sensors have been reported, for instance, the inertial sensors, chemical gas sensors, microphones, and pressure sensors. This presentation will introduce a novel double-side CMOS post-process established by the speaker’s group to realize various capacitance type CMOS MEMS sensors. In addition, the design and monolithic integration of various capacitive sensors, such as 3-axis accelerometers, pressure sensors, and tactile sensors, using the standard TSMC 2P4M CMOS process will be demonstrated. Other sensor integration can also be achieved by using the same approach. The presented CMOS MEMS platform shows a promising architecture for the existing CMOS technology while moving towards the era of "More than Moore."

Bio:
Weileun Fang was born in Taipei, Taiwan, in 1962. He received his Ph.D. degree from Carnegie Mellon University in 1995. He joined the Power Mechanical Engineering Department at the National Tsing Hua University (Taiwan) in 1996, where he is now a Professor as well as a faculty of NEMS Institute. From June to September 1999, he was a visiting associate at California Inst. Tech. He served as the TPC of IEEE MEMS (’04, ’07, and ’10), the regional TPC of Transducers’07, and the EPC of Transducers’09. He also serves as the International Steering Committee of Transducers conference from 2009; and the Chief Delegate of Taiwan for the World Micro Machine Summit from 2008. He is now on the Editorial Board of Journal of Micromechanics and Microengineering, and the Associate Editor of J. of Micro-Nanolithography, MEMS and MOEMS. He has established a MEMS testing and characterization lab. His research interests include MEMS with emphasis on micro fabrication/packaging technologies, CMOS MEMS, micro optical systems, micro sensors and actuators, and the characterization of the mechanical properties of thin films.

Forced Convection Boiling in Microchannels with Integrated Micro Heaters and Microsensors
Yi-Kuen Lee
Department of Mechanical Engineering, The Hong Kong University of Science and Technology

Forced convection boiling in microchannels has been studied for many years. However, the experimental results reported in the literature are not very consistent. In order to address this issue, microchannel with integrated micro heaters, temperature sensors and pressure sensors were fabricated on the same device using MEMS technology. The microchannels are covered by a glass wafer to monitor the bubble activity using video microscopy. Distributed micro heater elements on the device backside are used as the heat source, while the working liquid flow rate is adjusted using a syringe pump. Boiling curves of device temperature as a function of input power have been measured for various flow rates. The curves for increasing and decreasing heat flux exhibit a hysteresis loop, while the conditions corresponding to the onset of nucleate boiling and critical heat flux (CHF) are clearly distinguishable. The activity of the nucleation sites as well as the ensuing bubble dynamics, from incipience to departure, is found to depend on the channel height. The critical size, above which a nucleation site is active, along with the three aspects of bubble dynamics: growth rate, departure size and release frequency, have been characterized experimentally, and proper control parameters have been identified. With the help of numerical simulations, we found that the integrated micro temperature and pressure sensors along the microchannel were critical to determine the actual heat convection coefficient for forced convection of liquids in microchannels.

Bio:
Dr. Yi-Kuen Lee received his B.S. & M.S. degrees from National Taiwan University (NTU), Taipei, Taiwan in 1992 and 1995, respectively. After finishing the military service for the period of 1995 and 1997, he went to US and obtained his Ph.D. degree in Mechanical Engineering, majoring in Micro Electromechanical Systems (MEMS), under the guidance of Prof Chih-Ming Ho at UCLA in 2001. At UCLA, he developed a micro Particle Image Velocimetry system, a micro chaotic mixer and worked on the micro inkjet and single DNA dynamics in microfluidics projects. He has been working as an assistant professor on MEMS/NEMS research at HKUST from 2001 to 2007. He was promoted to Associate Professor in 2007. His current research topics includes micro electroporation cell chips for DNA transfection, micro/nano heat transfer, micro/nano electrophoresis for large DNA molecules, micro biometric sensors, integrated biosensor systems. He has published more than 85 international journal papers and conference papers.

CNTs as a Potential Material for MEMS
Chia-Min Lin
Nanoengineering and Microsystem Institute, National Tsing Hua University, Taiwan

The CNTs and flexible polymer are two promising materials and attract attentions. This talk presents a batch microfabrication process to form the CNTs-polymer composite on silicon substrate, and further implement the MEMS devices using this composite. Three CNTs-polymer MEMS devices are demonstrated. (1) Flexible CNTs electrode for neural recording : CNTs are partially embedded into a polymer film, so as to realize the flexible CNTs neural electrode. Measurements show the CNTs neural electrode has extremely low impedance to improve the recording signals. (2) Flexible CNTs photosensor for light detection : CNTs photosensor array are batch fabricated on flexible polymer. Measurements show the output photocurrent from CNTs photosensor varies linearly with input light intensity, and can be modulated by bias-voltage. (3) Monolithic integration of CNTs based physical sensors : CNTs are grown and patterned on Si-wafer and then integrated with MEMS structures to realize various CNTs-based physical sensors, such as pressure sensor and temperature sensor, on a single chip