Why Chip Material Matters
Microfluidic chip choice is not just about price. The wrong polymer can leach plasticizers into your sample, swell under organic solvents, soften at elevated temperature, or fluoresce so brightly that it drowns out the signal you are trying to measure.
The five workhorse polymers — PMMA, PC, PS, COC, and COP — span a wide range of chemical and optical properties. PMMA and PS are cheap and optically clear but chemically fragile. PC tolerates higher temperatures but cannot handle strong base. COC and COP cost more but handle the broadest chemistry, autoclave cleanly, and have the lowest auto-fluorescence.
Pick the polymer for the worst condition your workflow will see, not the average. A single DMSO wash can ruin a PMMA chip that performed flawlessly for months on aqueous buffer.
How the Score Is Computed
Each material starts at zero. For every solvent you select, the material gains +2 (good), +1 (limited), or −5 (bad) based on a static compatibility table compiled from published thermoplastic resistance data.
Temperature: +2 if the material withstands your maximum temperature, −4 if not.
Sterilization: +1 if the material survives your chosen method (autoclave, ethanol wipe, gamma, EtO), −3 if not.
Imaging: +2 for materials with low auto-fluorescence when you select fluorescence or confocal imaging, −2 for high-auto-fluorescence materials in those workflows.
The final score is clamped to 0–10. Materials with any "bad" solvent contact end up at the bottom of the table — even one disqualifying solvent should be enough to rule a material out.
When to Override the Recommendation
The matrix is a starting point, not a final answer. Three situations warrant manual override:
Brief contact only. If a "bad" solvent only contacts the chip for a few seconds (e.g., a quick DMSO rinse before flushing with water), a normally disqualified material may still work. The matrix is conservative — it assumes sustained contact.
Coated or surface-treated chips. A PMMA chip coated with PEG or parylene C inherits the coating's chemistry, not the substrate's. Override the score for the coating, not the bulk material.
Disposable single-use runs. If the chip is single-use and the experiment lasts under an hour, even a moderately incompatible material may be acceptable. Cost vs. risk.
