Hi everyone,

I am currently using 3D-printed molds to fabricate PDMS microfluidic devices. The molds are made of resin using DLP 3D printing technology. Despite numerous experiments, I’ve achieved very limited success in obtaining complete PDMS structures from the molds. I’m reaching out for advice—why is it so difficult to demold PDMS from these molds? What steps could I try next to improve my results?

Here are the details of my process:

The resin primarily consists of butyl acrylate.

After printing, the molds are cured under UV light for 1–2 hours.

The molds are then heated at 40–60°C for 6 hours to ensure the surface becomes solid and dry.

I apply surface treatments to reduce adhesion:

HMDS: I coat the mold surface with hexamethyldisilazane for 0.5~4 hours.

Siloxane-based mold release agent: Applied mold release agent as recommended by the PDMS supplier.

Unfortunately, these treatments have not significantly improved the demolding process. I have only managed to obtain a few intact PDMS structures.

I suspect the difficulty might be due to the roughness of the resin mold surface, but I am not certain. Recently, I tried plasma treatment on the mold surface (200 W, 1 minute), which showed slight improvement. However, when I extended the plasma treatment duration to 5 minutes, the PDMS became even harder to demold.

Has anyone faced similar challenges? What other methods or adjustments would you recommend? Any insights or suggestions would be greatly appreciated.

Thank you!