Surface treatment-assisted switchable transfer printing on polydimethylsiloxane films

Here, we report simple novel surface treatment-assisted switchable transfer printing (sTP) to pattern polydimethylsiloxane (PDMS) films of diverse thicknesses with prescribed microstructures. In the sTP, the PDMS decal inks are transferred from the “soft” side to the “hard” side, irrespective of the “soft” side coming from the PDMS stamp or the target PDMS substrate. Their “soft/hard” contrast with the corresponding cohesion difference can be finely induced and switched by a simple surface oxidation treatment, yielding the customized transfer patterns. In particular, multiple sTP with smart combinations of the additive/subtractive transfer mode can be easily realized for the controlled fabrication of unprecedented hierarchical patterns. We demonstrate the application of this methodology for forming microfluidic systems and as masks for surface patterning, and it is a powerful candidate for photolithography. Systematic studies further provide insights into the involved cohesion–fracture mechanism, which is highly expected to apply to other functional systems for advanced micro–nanofabrication.