Research

Microelectronics & Microsystems Research

In his ~60 years of research and mentoring at CWRU, Dr. Ko has supervised ~160 M.S. and Ph.D. Students in solid state electronics, micro-electronic technology, integrated circuit (IC) design, micro-sensors and actuators, implantable systems, and microelectromechanical systems (MEMS). Even during 2010 to 2014, he was still working and collaborating with Prof. Chris Zorman and Prof. Philip Feng, supervising a group of graduate students, engineers and postdoctoral scholars.

Dr. Ko taught the first transistor circuit course at the Case Institute of Technology to seniors in 1958, and built the Semiconductor Technology Laboratory for teaching and research in 1961. The laboratory fabricated the world's first integrated pressure sensor and integrated telemetry circuit in the 1960s. Dr. Ko was responsible for the first electronic circuits, solid state electronic devices and technology courses at Case. Our undergraduate/graduate students graduated in the 1960-75 period were the choice of electronic industries and contributed significantly to the advancement of the newly emerging semiconductor electronics industry. We hosted visiting professors from England, France, Belgian, Norway, Yugoslavia, Japan, Korea and other countries.

Between 1959 and 1994, Dr. Ko established and maintained at CWRU an internationally recognized center of excellence in solid state electronic device and technology, medical implant electronics and systems, micro sensors and actuators, and microelectromechanical systems (MEMS). His Ph.D. thesis analyzed the transient behaviors of P-N junctions that lifted the limitation of computer clock frequencies below 1 MHz. He was invited to give a lecture at the Bell Labs and become a consultant to IBM in 1960. His first Ph.D. student’s thesis solved the mystery of threshold drift in MOS transistors that removed a significant roadblock facing the electronic industry in the 1960’s. He worked in implant telemetry, medical instruments, sensors and actuators, and micro-technology for 35 years. After retiring in 1993 at the age of 70, he joined the emeritus faculty and maintained an active research program which continues till Fall 2014. He and his graduate students studied functional MEMS devices including integrated sensors for medical and industrial applications. Of the many patents assigned to Prof. Ko, the invention of the touch-mode pressure sensor for tire inflation applications has proven to be the only pressure sensor that can withstand the 300^oC tire molding processes and 1000% overload, becoming the first embedded sensor for tire pressure monitoring.

After retirement in 1993, he continued his research, supervising 32 graduate students with grant-based research support. He freely discussed ideas and design problems with students and faculty members that visited him during regular office hours or on weekends. In 2012, a full 20 years after his retirement and almost at 90, he received an NIH R21 grant to develop a micropackaging technology for implantable micro devices and systems. In the recent 5 years, he has been developing proposals on removing the technical roadblocks associated with real time home/mobile care of patients.

Dr. Ko was the Principle Investigator (PI) of NIH Microelectronic Laboratory for Biomedical Sciences and Medical Electronics Resources from 1964 to 1984, as well as the PI of NASA, NSF, and industrial projects. These projects supported over 80 graduate students. From 1982 to 1993, he was a co-investigator of NIH, NSF, DARPA and industrial projects, and supported more than 22 graduate students. From 1994 until 2010, he had industrial research support from Goodyear Tires, Timken Corp. and others, as well as NSF and NIH grants in collaboration with Prof. Darrin Young and others in the Department of EECS, supporting 25 of 32 graduate students.

Biomedical Research

Dr. Ko was the director of Engineering/Electronics Design Center from 1970 to 1981, and director of the Microelectronics Laboratory and Biomedical Electronic Resource of the NIH from1967 to 1984. His team designed and fabricated hundreds of K-5 and M-1 series bio-telemetry transmitters and provided them to field biology researchers both inside and outside of CWRU between 1968 and 1975. These telemetry systems were used in biomedical research and field biology exploration. Some results were published in top journals, including Science.

He and the team studied and demonstrated the first implantable closed loop prosthetic control system for muscle control in living subjects in l966. Many functional electrical stimulation applications today can be traced to these demonstrative works.

He studied the full range of problems associated with medical implant electronics and prostheses. He pioneered work in short range RF communication and wireless powering, implant packaging, body reactions to semiconductors and silicon compounds and micropower telemetry circuits and systems. The CWRU Nasal Piece for continuous positive airway pressure system, now used in premature baby care units worldwide was designed by Prof. Ko’s team in 1975.

He pioneered long-term stable pressure sensors for implant applications, studied the source of instability in sensors which led to the innovative approaches in packaging of implantable sensors and instruments. He designed a capacitive pressure sensor with time stability better than 1% over a 10 year operational lifetime,-a world record. He pioneered implantable intracranial pressure monitoring for hydrocephalic patients in 1980 and middle ear hearing aids in1987.