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Figure 3: Real-time measurement of the continuous curing induced adhesion. (a) Comparison of the real-time force-displacement curves of liquid resin on different curing interfaces during the 3D printing process. Inset is the enlarged part of the force-displacement curve between 20 and 40 mm region for PDMS, F-PDMS, and silicone oil-PDMS surface. Violet, magenta, black, red, and orange lines are force-displacement curves of quartz, F-quartz, PDMS, F-PDMS, and the silicone oil swelled PDMS interfaces, respectively. (b) The real-time force-displacement curves of liquid resin on the ultra-low adhesive S-PDMS curing interfaces during the 3D printing process. Inset is the enlarged part of the force-displacement curve between 20 and 40 mm region with an elevating speed of 10 mm/min. (c) SEM or stereomicroscope images of the PDMS surface, silicone oil swelled PDMS, and the S-PDMS surface used as the curing interface in the initial state and after continuous printing for 40 mm. (c1) and (c2) are the SEM images of PDMS surface before UV curing and after continuously UV curing for 40 mm, respectively. (c3) and (c4) are the SEM images of S-PDMS surface before UV curing and after continuously UV curing for 40 mm, respectively. (c5) and (c6) are the stereomicroscope images of silicone oil swelled PDMS surface before UV curing and after continuously UV curing for 40 mm, respectively. (d) Curing induced adhesion versus lifting velocity of supporting plate and light intensity of UV source on PDMS surface. Grey surface is the indication of the surface where adhesive force is 5 mN. (e) Curing induced adhesion versus lifting velocities of supporting plate and light intensities of UV source on S-PDMS surface. Grey surface is the indication of the surface where adhesive force is 5 mN. (f) and (g) are real-time monitoring of resin refilling process through trace tracking of three nonreactive micro-particles (gold powder, ~100 mesh, Alfa) in the liquid resin during the continuous UV curing process. (f1) Initial position of the micro-particles in the liquid resin. Orange, blue, and red circles indicate the initial position of micro-particle A, micro-particle B, and micro-particle C, respectively. (f2) Final position of the micro-particles in the liquid resin and cured resin structure. Orange, blue, and red circles indicate the final position of micro-particle A, micro-particle B, and micro-particle C, respectively. (g) The trajectories of three microparticles versus time. Orange, blue, and red lines indicate micro-particle A, micro-particle B, and micro-particle C along with the supporting plate continuously lifting process, respectively.