Method for manufacturing a polydimethylsiloxane master mold for double-casting using plasma and alcohol treatment, and a polydimethylsiloxane master mold for double-casting manufactured by said method

Manufacturing Technology for PDMS Double-Casting Master Molds Based on Plasma and Alcohol Surface Passivation

This technology involves creating a PDMS master mold, converting surface functional groups to OH groups via plasma treatment, and then passivating those OH groups with alcohol to produce a master mold that does not react with PDMS solution during double-casting.

While PDMS double-casting is widely used in microfluidic chip and bioMEMS fabrication, it often faces issues where liquid PDMS thermodynamically interacts with the already-cured master mold, causing the two elastomers to bond. Additionally, uncrosslinked low-molecular-weight siloxanes can migrate to the surface and react during secondary casting, necessitating cumbersome, separate monomolecular coating processes.

This technology achieves a master mold with excellent release properties by using only plasma and ethanol/methanol treatment to remove reactive functional groups and leach out residual prepolymers. It allows for the precise replication of objects with high aspect ratios and 3D microstructures. Applicable to microfluidic chip, bioMEMS, and micropattern device fabrication, it ensures consistent casting quality through simple surface treatment without the need for additional coatings.

‍

‍

Key Features:

• A method for manufacturing a master mold for double-casting, comprising the steps of fabricating a polydimethylsiloxane master mold, treating the mold with plasma, and then treating it with alcohol.
• A configuration that passivates OH groups converted on the surface by plasma with alcohol to remove functional groups capable of reacting with the PDMS solution used for double-casting.
• Process conditions including a PDMS base solution and curing agent in a weight ratio of 5:1 to 20:1, with plasma treatment for 10 to 90 seconds.
• A method of leaching out prepolymers remaining inside the PDMS through ethanol or methanol treatment, followed by pouring PDMS solution onto the manufactured mold for double-casting.

‍

This invention was developed with support from the Ministry of Science and ICT for the development of a testis organoid-based fusion platform capable of micro-stimulus control.

‍