Development of Advanced Biomimetic Technologies Inspired by Leaf Transpiration.

Abstract

Plant leaves are inevitable for survival, because their transpiration plays as a high efficient hydraulic pump. However, numerous mechanisms underlying the biophysical principles for regulating sap transport remain unclarified, and inevitably advantageous features of plant leaves have not been fully utilized yet. In this thesis, the basic principles of leaf transpiration are investigated and several transpiration inspired biomimetic technologies are derived. To systematically examine the structures and functions of hydraulic pathways for leaf transpiration, analogue hydrogel models inspired by leaf mesophyll structures are fabricated, and water transport in the models are investigated. In addition, the effect of morphological parameters of porous media for effective mass transport was explored experimentally and analytically. The revealed information on mass transport in plant-inspired porous structures would be used to establish a new design rule or optimize the geometry and performance of advanced bio-inspired systems for practical applications. Inspired by the dynamic function of leaf stomata which are well-organized multisensory turgor operative valves for regulating transpiration, stomata-inspired membrane (SIM) having thermo-responsive functionalities is fabricated. The fabricated SIMs can regulate the shape of pores by the help of thermal-responsive hydrogel. By the simple and controllable photopolymerization-based patterning, this stimuli-responsive SIM will be potentially applied to numerous engineering applications in the future. Finally, by integrating the above leaf mesophyll inspired hydrogel and the SIM, a novel leaf inspired micropump (LIM) is developed. A compact and portable LIM can efficiently transport water upward against gravity by means of water potential difference. It can also smartly manipulate the pumping timing in response to thermal stimuli. The LIM will be utilized in a variety of microfluidic and biomedical devices, such as POC systems and organ-on-a-chips to supply bio-samples in a smart manner. Conclusively, the systematic analysis on the underlying mechanisms of leaf transpiration leads to open great opportunities for developing innovative biomimetic technologies.