1. Introduction to PDMS
Polydimethylsiloxane (PDMS) is a high molecular weight polymer with the chemical formula (C₂H₆OSi)_n.
PDMS material has excellent electrical resistivity, good biocompatibility, low cost, and ease of processing. When combined with a chip lab, it can be used to fabricate PDMS microfluidic chips.
This chip is widely used in fields such as biological diagnosis, drug analysis, food safety, and environmental monitoring.
2. Introduction to PDMS molding molds
| Comparison of different mold parameters | ||||
| SU-8 Mold | PMMA Molds | 3D printed molds | Silicon Mold | |
| Material | SU-8 photoresist | PMMA | Photosensitive resin/PLA | monocrystalline silicon |
| craft | lithography | Laser cutting/CNC | 3D printing | deep silicon etching |
| accuracy | ~10μm | ~100μm | 20-50μm | Up to submicron level |
| costs | Height | low | medium | extremely high |
| durability | More than 50 times | ~50 | ~20 | >100 |
1) SU-8 mold processing technology
The mask required for chip design is selected based on precision, choosing either film mask or chrome plate mask; after coating, pre-baking, exposure, post-baking, and developing, an SU-8 mold is produced.
2) Acrylic mold processing technology
The primary processes for manufacturing PMMA molds are CO2 laser ablation and CNC machining.
3) 3D printing mold processing technology
Common 3D printing technologies are mainly divided into fused deposition modeling (FDM), stereolithography (SLA), selective laser sintering (SLS), and layered solid manufacturing (LMO).
4) Pure silicon mold processing technology
Pure silicon molds are made using deep dry ion etching (DRIE) technology, Bosch process, and KOH solution.
3. PDMS chip molding process
Mix the adhesive, evacuate the vacuum, pour the PDMS adhesive (optional models: Dow Corning 184 or Momentive 615); after curing, demolding, cutting, and drilling holes, clean with a plasma cleaner before bonding.
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