Design and analysis of magnetic-assisted transfer printing

As a versatile yet simple technique, transfer printing has been widely explored for the heterogeneous integration of materials/structures, particularly important for the application in stretchable and transient electronics. The key steps of transfer printing involve pickup of the materials/structures from a donor and printing of them onto a receiver substrate. The modulation of the interfacial adhesion is critically important to control the adhesion/delamination at different material-structural interfaces. Here, we present a magnetic-assisted transfer printing technique that exploits a unique structural design, where a liquid chamber filled with incompressible liquid is stacked on top of a compressible gas chamber. The top liquid chamber wall uses a magnetic-responsive thin film that can be actuated by the external magnetic field. Due to the incompressible liquid, the actuation of the magnetic-responsive thin film induces the pressure change in the bottom gas chamber that is in contact with the material/structure to be transfer printed, leading to effective modulation of the interfacial adhesion. The decreased (increased) pressure in the bottom gas chamber facilitates the pickup (printing) step. An analytical model is also established to study the displacement profile of the top thin film of the gas chamber and the pressure change in the gas chamber upon magnetic actuation. The analytical model, validated by finite element analysis, provides a comprehensive design guideline for the magnetic-assisted transfer printing.