SUBJECT: Ph.D. Dissertation Defense
BY: Jungchul Lee
TIME: Wednesday, March 28, 2007, 2:00 p.m.
PLACE: Love Building, 210
TITLE: Fabrication, Characterization, and Application of Multifunctional Microcantilever Heaters
COMMITTEE: Dr. William P. King, Chair (ME)
Dr. Yogendra Joshi (ME)
Dr. Ari Glezer (ME)
Dr. Mark Allen (ECE)
Dr. Oliver Brand (ECE)


The microcantilever is perhaps the most widely used microelectromechanical systems (MEMS) device. Scanning Probe Microscopy (SPM) uses a microcantilever as a stylus to scan a surface of interest with sub-nm resolution. Besides SPM applications, microcantilevers have been employed for acceleration sensing, radio frequency MEMS switches, bio/chemical detection, thermomechanical data storage, nanomaterial synthesis, and nanoscale lithography tools. To incorporate such specific functionality into a microcantilever, some modifications have been proposed. Well known examples include heated cantilevers, piezoresistive cantilevers, and piezoelectric cantilevers. This dissertation focuses on fabrication, characterization, and application of heated cantilevers and piezoresistive cantilevers. The first objective seeks to understand thermal, electrical, and mechanical characteristics of heated cantilevers in various conditions. Experiments investigate thermal, mechanical, and coupled behaviors of the heated cantilevers under DC, AC, and transient electrical heating. Raman spectroscopy measures local temperature and qualitative intrinsic stress with high spatial resolution. Based on the thorough understanding from device characterization, cantilever type micro hotplates and small array of heated cantilevers with integrated piezoresistive sensors are fabricated and characterized. The second objective is to construct novel metrology tools using the fabricated and well characterized microcantilever sensors. Heated microcantilevers are suggested to study sub-continuum heat transfer from a micro heater to ambient gas environment in a wide range of pressure. Microcantilever sensors are employed to study the free microjets emanated from microfabricated nozzles. Piezoresistive cantilevers measure jet thrust, velocity, and break-up distance of the liquid microjets and heated cantilevers investigate heat transfer characteristics and phase change phenomena during the microjet impingement.