The National Natural Science Foundation of China, No. 11302039, 2014.01-2016.12
Flexible electronics, capable of accommodating large deformation and complex curvilinear surface, have better application prospects than conventional electronics. Transfer printing approach, assembling functional devices from donor substrate to flexible receiving substrate, is the key problem in the fabrication of flexible electronics. Current transfer printing approaches emphasize on changing the stamp structure and using external force/interfacial adhesion to realize a successful transfer printing, ignoring the enhancement on transfer printing invoked by the response of stamp to external stimulus. Inspired by the unique behavior of smart soft materials, such as shape memory polymer returns to its initial configuration under heating, this project uses smart soft material shape memory polymer as stamp, controls the strong-weak transition of interfacial adhesion under external stimulus for substrates with different adhesion, and realizes the high-efficiency reversible dynamically controllable transfer printing. With experiments, theoretical analysis and finite element simulations approaches, this project analyzes the configuration change of stamp under external stimulus and the adhesion, separation of stamp/ink, proposes the critical condition of interfacial crack in different stages of transfer printing, reveals the law and mechanism of influence of external stimulus on the strong-weak interfacial adhesion transition and transfer printing, provides useful theoretical guide and possible approach for the design of transfer printing system and fabrication of flexible electronics.