Mission Statement
A student run publication that covers the people, the research and the events that occur within the UC San Diego Bioengineering Department. It also serves as outreach for people interested in learning about bioengineering.
Michael Hu
Fall 2017
YC Fung: Father of Biomechanics

Bio: Professor Yuan-Cheng (Y.C.) Fung originally earned his Ph.D. in Aeronautics and Mathematics from Caltech in 1948, the field to which he dedicated the first 20 years of his post-graduate work. In 1966, Professor Fung moved to UC San Diego, where he founded the Bioengineering Department alongside Professor Benjamin Zweifach and Professor Marcos Intaglietta, and continued to work for the remainder of his career.

In this edition
of Research Highlights, we examine the historical impact of the concepts and theories established by Professor Fung over the course of his career. With hundreds of publications spanning over 6 decades and encompassing almost the entirety of the biomechanics field, it is impossible to identify a single work as a highlight for Professor Fung’s research. As such, we focus instead on the broad impacts of his work, particularly in establishing the foundations for modern bioengineering.

On the whole, much of Professor Fung’s research is embedded in biological concepts that are now taken for granted and taught as fundamental aspects of bioengineering. Specifically with regards to biomechanics, one of Professor Fung’s most notable contributions was to identify a method by which stress-strain relations could be applied to biological tissue. As a whole, non-living materials are viewed as being either elastic, meaning that applied stress is directly related to strain, or viscous, meaning that applied stress is instead related to strain rate. Because living tissues exhibit properties of both, subjecting them to analysis by established mechanical laws was once thought to be impossible. However, by developing an exponential stress-strain relation accounting for the viscoelastic properties, a relation now known as Fung’s Law, Professor Fung was able to produce the first constitutive analysis of soft tissue. By expanding upon the simplifying assumptions used, it then became possible to predict the mechanical behavior of biological materials using standard mathematical models, thereby laying the foundations for modern biomechanics[3] .

Beyond his contributions towards establishing the principles of biomechanical analysis, Professor Fung is also widely acknowledged as being the first to propose the founding of a bioengineering sub-discipline focused on applying engineering principles to the analysis of tissues as a whole, the field now known as “tissue engineering”[1]. While novel at the time, the discipline itself grew rapidly following conception, and has now become an integral component of nearly all bioengineering departments across the country. Another significant historical input was his efforts in establishing the idea that blood vessels in a relaxed state were still subject to physical stresses[4]. Prior to this, it was widely believed that blood vessels lacked residual stresses and strains entirely. However, Professor Fung’s proposal of the opposite significantly altered the methodologies by which hemodynamic studies were conducted, and catalyzed the idea that tissue growth was related to stress[5]. Additional contributions worth highlighting include the proposal that red blood cells had liquid interiors[7], the development of the idea that shear stresses and fluid pressure can have an impact on the gene expression of a cell, confirmation that red blood cell flow at a capillary level does not follow standard laminar flow patterns, and the characterization of fundamental biomechanical properties of skin that eventually allowed for the development of successful human skin grafting treatments[1] .

Predictably, contributions of such magnitude have earned Professor Fung a large assortment of awards throughout his career. He was elected to the National Academy of Engineering, the National Institute of Medicine, and the National Academy of Science, being one of only a handful of individuals to be elected to all 3 organizations. He is also a recipient of the President’s National Medal of Science, over twenty honorary doctorates from universities in China and the United States, and a significant collections of awards from prominent organizations including the Biomedical Engineering Society, the American Society of Biomechanics, the International Society of Biomechanics, and the American Association of Mechanical Engineers[3]. Possibly even more prominent than all of these however, is that he received his own namesake dwarf planet from the International Astronomer’s Union, dubbed 21043 Fungyuancheng in 2012; an honor given even more rarely than the Nobel Prize[6], and one that is certainly suitable for such a giant in the field.

Sources

1. “A Proposal to the National Science Foundation for An Engineering Research Center at UCSD, Center for the Engineering of Living Tissues”, UCSD #865023, courtesy of Y.C. Fung, August 23, 2001.

2. Chien, S., & Fung, Y. (2010). Tributes to Yuan-Cheng Fung on His 90th Birthday: Biomechanics. Hackensack, NJ: World Scientific.

3. Kassab, G. S. (2004). Y.C. "Bert" Fung: The Father of Modern Biomechanics. Mechanics and Chemistry of Biosystems,1(1), 5-22.

4. Liu, S.Q. and Fung, Y.C.: Zero-stress states of arteries. J. Biomechanical Engineering 110: 82-84, 1988.

5. Nahum, A. M., & Melvin, J. W. (1993). Accidental Injury: Biomechanics and Prevention. Berlin: Springer.

6. Robbins, G. (2012, July 31). Asteroid Named after UC San Diego Professor. San Diego Union-Tribune. Retrieved April 23, 2017.

7. Tong, P. (2004). Yuan-Cheng Fung: A Scientific Giant and a Kind Man. Mechanics and Chemistry of Biosystems,1(1), 1-4.