PDMS microfluidic chip
High Transparency: Exceptional optical clarity within the 240–1100 nm wavelength range.
Gas Permeability: Highly permeable, providing excellent oxygen and carbon dioxide flux.
Mechanical Flexibility: Soft elastomer nature ensures high impact resistance and prevents fracture.
Thermal Range: Sustains long-term stability in harsh environments from -50°C to 200°C.
Cost-Efficiency: Economical material suitable for large-scale replication and prototyping.
Biocompatibility: Inherently non-toxic and biocompatible.
Chemical Inertness: Exhibits high chemical stability under standard conditions.
Applications: Ideal for cellular assays, drug screening, cell trapping, and biochemical research.
Minimum Feature Size: Resolvable down to 2 μm.
Channel Dimensions: Minimum width of 5 μm; minimum height of 10 μm.
Feature Spacing: Minimum distance between adjacent channels is 20 μm.
Array Fabrication: Supports micro-pillar/micro-well arrays (circular or square) and PDMS 96-well plates.
Aspect Ratio Limit: Minimum pillar diameter is 10 μm (Note: For concave molds, the aspect ratio must not exceed 1:1).
Channel Height Error: Δ h = ± 5% of the channel height.
Feature Height Accuracy: ± 5% of the channel height.
Wall Verticality: Side-wall taper profile within ± 3°.
Thin Film Control: Thickness ranges 50–500 μm with a strict 2% tolerance.
Mechanism: Oxygen plasma alters surface chemistry to generate silanol groups (Si-OH).
Hydrophilic Lifetime: Converts native hydrophobic surfaces (water contact angle ~ 108° ± 7°) to hydrophilic for approximately 30 minutes.
Anti-Adsorption: Inhibits non-specific adsorption of hydrophobic and negatively charged molecules.
Covalent Bonding: Enables surface functionalization via trichlorosilane or atomic-level Si-O-Si covalent bonding to oxidized glass.
| Fluid Category | Representative Fluids | PDMS Performance & Recommendation |
|---|---|---|
| Compatible | Water, Glycerol, Methanol, Ethanol | No penetration or continuous deformation. Safe for use. |
| Marginal | Acetone, Propanol, Pyridine | Minor swelling and structural deformation. Use with caution. |
| Incompatible | Diisopropylamine, Chloroform, Ethers | Severe swelling and geometric distortion. Do not use. |
Key Notice: PDMS chips are highly susceptible to chemical contamination, difficult to clean thoroughly, and have low reuse rates. They are primary intended as disposable single-use chips.
Filtration Requirement: All solvents must be filtered prior to injection into the system.
Critical Channels: Stricter filtration is mandatory for channels under 20 μm to prevent clogging from particulates.
Purge Residuals: Use strong pressure to push the chemical reagents out of the channels.
Solvent Displacement: Fill the reservoirs with a fluid miscible with the reagent. Flush until droplets emerge from the outlet.
Deionized Water Rinse: Flush thoroughly with DI water.
Gas Desiccation: Purge the channels with air, nitrogen (N₂), oxygen (O₂), or argon (Ar) until completely dry.
| Substrate | Contaminant Type | Recommended Method & Crucial Warnings |
|---|---|---|
| PDMS | Organic Residues | Ethanol wash → DI water flush → Bake dry. |
| PDMS | Inorganic Residues | Direct DI water flush → Bake dry. |
| Glass | Various Residues | Robust chemical resistance; match solvent to residue. Never use hydrofluoric acid (HF). |
| PMMA | Various Residues | Tolerates only weak inorganic acids/bases. Organic solvents are strictly prohibited. |
Operational Warning: Avoid high flow rates during cleaning to prevent delamination or structural damage caused by excessive hydraulic pressure.
Thermal Curing: Post-bonding baking at 80–90°C for 15–30 minutes significantly enhances bond strength.
Plasma Medium: Ambient room air plasma treatment is sufficient and highly effective for standard bonding routines.
Contamination Control: The PDMS surface must be completely free of dust, lint, and particulate matter before bonding.