Increasing evidence has shown that living cells respond to mechanical stimuli not only mechanically but also biologically. But how they respond to mechanical stimuli and the mechanisms through which they transduce the mechanical stimuli into biological response remain largely unclear. In this research, novel versatile and flexible microelectromechanical systems (MEMS) sensors were developed for measuring mechanical response of single living cells. These sensors measure cell force response in the range of one nano newton to one micro newton, which is largely inaccessible for the current prevalent techniques for the study of cell mechanical response such as atomic force microscopy (AFM), optical tweezers, and magnetic twisting cytometry. These sensors have been used to study the mechanobiological response of fibroblasts, endothelial cells, and neurons. The major findings of the studies include: The force response of monkey kidney fibroblasts is strongly linear, reversible and repeatable under large deformations, with a small stiffening at the initial deformation stage; Actin filaments play a dominant role in taking the cellular internal forces; Mechanical indentation/compression may induce actin agglomeration inside the cell, which supplies a perfect example of cellular mechanotransduction; The in vivo stretch force response of Drosophila axons is linear, there is a rest tension in the axons and they maintain this rest tension, and tension in the axons is required for normal synaptic function and muscle twitches may be involved in tuning this tension.
Dr. Shengyuan Yang is currently an associate professor in the Department of Mechanical and Civil Engineering at Florida Institute of Technology (Florida Tech) in USA. Dr. Yang earned his Bachelor of Engineering degree in 1993 from the University of Science and Technology of China and his Ph.D. degree in 2007 from the University of Illinois at Urbana-Champaign in USA, both in Mechanical Engineering. Before came to USA, he worked as a research associate in Japan and Singapore for four years. His current research interests include micro and nano electro mechanical systems (MEMS/NEMS), cell mechanics and mechanobiology, and bioengineering/biomedical engineering. After joined Florida Tech in the Fall of 2007, Dr. Yang received the prestigious National Science Foundation (NSF) CAREER Award in 2009. In his research at Florida Tech, he invented the first class of curvature-defined surfaces for uses in cell and tissue culturing and in other surface and interface applications, and the first class of sensors for decoupled-measuring of three-dimensional forces in air or liquids, for which he is the owner of six US patents and pending patents and a China Utility Mode patent. Dr. Yang reported the first experimental evidence to show that the curvature of a substrate alone can induce the differentiation of stem cells.