Fig. 4: Wrap-like, multilayer, selective, and interior transfer printing behaviors.

a A petal-shaped LED array wrapped around a glass sphere (left), along with I–V curves (right) of the LED array before and after transfer printing. The inset displays the 2D layout and circuit schematic diagram of the petal-shaped LED array, and the illuminated LED array after printing. b Schematic illustration (left) and real-time resistance change during the loading and unloading of a 200 g weight (right) for a flexible pressure sensor. The inset shows the experimental image during loading, as well as the response and recovery time. c Schematic illustration (left) and experimental images (right) of selective transfer printing. Yellow (PI) and black (PET) pellets, respectively, represent target and non-target objects. The selective transfer printing process includes: the syringe array with D-shaped patterns being pulled up and dipped into the soap solution (Step i); these syringes are aligned with target objects and pushed down to generate a related soap bubble array (Step ii); the syringe array is lifted to pick up target objects from the donor substrate (Step iii); the soap bubble array is brought into contact with the receiver substrate (Step iv); the soap bubble array bursts to complete transfer printing in a damage-free manner(Step v), with a top view after printing. d Sequentially deflating and inflating the soap bubble to realize the printing onto an interior cavity of a hollow sphere: deflating the soap bubble to contract the hosted electronics to pass through the small incision (Step i); inflating the soap bubble to expand the electronics to conformably match the curved interior cavity (Step ii); bursting the soap bubble to complete the printing process (Step iii), with the top view after printing.