Fig. 2: SCL experiments, acoustic streaming, measured pressure maps, and 3D printing progress.

a Schematic of the setup used for SCL experiments inside the cavity filled with the luminol solution in which the apparatus tip is placed adjacent to the platform at different distances (h) and the blue light patterns of SCL captured using the DSLR camera. b, c SCL patterns captured using a DSLR camera for the aperture (b-i to b-iii) ID = 1.5 mm (c-i to c-iii) ID = 4 mm. d Schematic of an experimental setup for pressure map measurements. e Measured pressure maps using needle hydrophone for three planes located at different distances from the apparatus tip (i) dp = 0.24 mm (ii) dp = 0.74 mm (iii) dp = 1.3 mm. f, g Acoustic pressure and acoustic intensity fields computed from linear acoustic simulation. h Deposited acoustic power graph extracted from linear acoustic simulation results. i Simulation results of acoustic streaming inside a cavity filled with PDMS at different h_s between the aperture and bottom of the cavity (i-1) h_s = 1 mm (i-2) h_s = 50 μm. j, k Footage from high-speed imaging of the 3D printing process and observation of SUAR during the fabrication of (j-i and j-ii) porous wall from PDMS with the mixing ratio of 10:1 and (k-i and k-ii) transparent wall from PDMS with the mixing ratio of 16:1, using the printing aperture diameter of 1.5 mm. Experimental conditions: P = 5 W, DC = 100%, f = 2.15 MHz; the ISO and exposure time of the DSLR camera for SCL experiments were set to 3200 and 30 s, respectively