Figure 5.

3D‐printed porous superhydrophobic (SHB) microfluidic device. a) Schematic showing the microfluidic fabrication via assembly of a 3D‐printed porous SHB channel and a transparent nonporous SHB cover. b) Photograph showing water droplets forming an almost spherical shape in the 3D‐printed porous SHB channel. c) Cross‐sectional SEM images showing the porosity of the 3D‐printed SHB channel. d) Snapshots of a video (Video S4, Supporting Information) showing a water droplet moving freely in the assembled SHB microfluidic device. e) Snapshots of a video (Video S5, Supporting Information) showing the color change of bromothymol blue solution in the microfluidic device due to CO₂ diffusion. The CO₂ concentration in the environment is indicated on the top, while the flow rate of the solution is given at the bottom. f) UV–vis spectrum of the bromothymol blue solution at the inlet and outlet of the microfluidic device at a flow rate of 25 µL min⁻¹. g) Ratio of yellow color width to the width of particular loop of the channel at various positions under different flow rates. h) Ratio of acidic yellow area to the channel area (i.e., total area of green and yellow) under different flow rates.