Prof. Seung-Hyun Kim's research interests are in the area of piezoelectric materials development, MEMS processing and energy applications. He has published over 130 refereed journal papers and 200 presentations (including 35 invited presentations), and has served as an organizing committee member and a reviewer of numerous international conferences and journals. Prof. Kim's educational and academic activities cover experimentation and applications of electronic materials and micro-and nano-scale devices.
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1. Design and development of piezoelectric thin film-based vibration MEMS energy harvesting devices
The objective of this research is to design, fabricate, and demonstrate unique piezoelectric tunable MEMS energy harvesting device. New challenges to achieve a robust tunable energy harvesting device will overcome the limitations of current state-of-the-art devices that harvest energy within a narrow vibration frequency range. Process development of integrating piezoelectric materials into MEMS will significantly advance the functionality of the device.
2. Environmentally friendly non-lead based piezoelectric thin film ; materials and energy harvesting devices
As described previously, piezoelectric materials are of importance due to their high energy-conversion efficiency, in particular from mechanical energy into electrical energy, and vice versa. New piezoelectric materials are urgently required to replace the lead zirconate titanate (PZT) system, for which the toxicity of the lead component is a major concern. The objective of this research is to develop thin film-based piezoelectric materials from the promising sodium potassium niobate tantalate (K,Na)(Nb,Ta)O3 system and polymer-based piezoelectric films. These materials will be used to develop a new class of low cost flexural mode electromechanical transducers, suitable for use in a wide range of energy harvesting applications as an alternative material for conventional PZT system.
3. Oxide-based thermoelectric energy conversion materials and devices
This research is for the development of a new route to functional polymer based substrates and flexible electronics. It provides a processing platform to dramatically expand the functionality and capability of the ubiquitous flexible substrate, and also explores the addition of new functionality to flexible electronics. The objective of this research is to develop the capability to integrate additional electronic functionality onto low cost substrates such as printed circuit boards (PCBs) and flexible substrates. The priority functionality selected for this research is the demonstration of integrated oxide thermoelectrics. Our approach is to use a thermoelectric unit to recover the dissipated heat, and convert it back into useful power on the multifunctional substrates.
4. Small scale electromechanical devices based on functional oxide thin films
The application in this area includes actuators, sensors, and transducers. The development of microelectronic devices requires highly functionality and sensitivity of materials. One of candidates for MEMS device, in particularly in sensing and actuating component, is perovskite type materials due to their large piezoelectric coefficient. However, the properties of thin film ferroelectrics are not well known compared to those of bulk due to many sensitive processing parameters, different stress condition, scaling effect and so on. Therefore, we developed a robust chemical solution synthesis process affording the isolation and control of physical and chemical parameters that strongly influence the ferroelectric and piezoelectric response. Research into materials with ferroelectric and piezoelectric properties is at the vanguard of materials science research, due to their ability to make electronic devices smaller and perform more effectively.
5. High-k passive device and power capacitor applications
Many perovskite-structured films, including (Ba,Sr)TiO3, Pb(Zr,Ti)O3, and the relaxor ferroelectric do not match the properties of bulk single crystals or ceramics. Instead, significant deviations from the bulk properties are observed as consequences of non-stoichiometry, defects, internal fields and reduction of extrinsic contributions to the permittivity, substantial in-plane strains. The consequence is that films frequently show peak permittivities that are rarely within an order of magnitude of a well-processed ceramic. Due to this limitation, there is an interest in developing alternative materials and/or processing for applications including capacitors for integrated circuit applications, integrated resistor-capacitor networks, and tunable circuit components. The rapid development of industry will require more integrated components for facilitating miniaturization of devices. Although many interesting results were obtained, there are still lots of issues to be approached in developing process and understanding physics of materials and devices. Scientific issues we are trying to pursue in this subject include the source of the dielectric relaxation and the tunability, the structure-property relation in dielectric breakdown, understanding the role of dopants in thin film dielectrics on microstructure and phase transition. We would like to explore engineering issues such as performance and compatibility with industrial requirements as well.
1. Gift grant: Bio-compatible Flexible Electronic Systems ($700,000) Source of support : Company gift grant ($140,000/year for 5 years since 2015)
2. Brown- Xerox Collaboration on Innovative Lead-Free Piezoelectric Materials and Actuators ($110,000/year) (2014 - current)
3. A Xerox-Brown Collaborative Investigation of Environmentally Friendly Piezoelectric Materials for High-Strain Actuator Applications ($350,000) Source of support : NSF ECCS (GOALI) 3 years project (2014-2017)