*2.3. Preparation of Amino-Functionalized PDMS Film*

The flexible PDMS film was prepared by mixing 6 g of the main agent with 0.6 g auxiliary agent. The mixture was stirred with a glass rod and poured into a 9 cm plastic petri dish to form an even and thin fluid layer. It was then transferred to a vacuum oven to remove the bubbles and heated at 60 ◦C for 10 h. After solidification, the transparent PDMS film was cut into small slices of squares (~5 mm × 5 mm) for further use.

For the chemical modification of the PDMS film, a series of APTES ethanol solutions were prepared with different concentrations, from 0.002% to 2% (Vf). Square slices of the PDMS films were immersed in APTES solutions for 2 h. After that, the amino-functionalized PDMS was rinsed with deionized water multiple times before drying at room temperature.
