FUNDAMENTALS
Paper Microfluidics (µPADs) Explained
Paper microfluidics uses ordinary porous paper to move and test fluids — no pumps, no power, very low cost. It is the technology behind lateral-flow tests and a growing class of paper-based diagnostics. Here is how it works.
What is paper microfluidics?
Microfluidic paper-based analytical devices (µPADs) pattern hydrophilic channels into paper bordered by hydrophobic barriers. Fluid wicks through the channels by capillary action alone — no external pump or power needed.
How they are made
Channels are defined by wax printing, photolithography or simple cutting, and reagents are spotted onto detection zones that change colour (or generate an electrochemical signal) when the target is present.
Strengths
- Extremely cheap and disposable.
- Portable and equipment-free — ideal for low-resource and field settings.
- Pump-free and power-free, the basis of point-of-care lateral-flow tests.
Limitations
- Limited fluid control and quantification compared with channel-based chips.
- Evaporation and sample retention in the paper.
- Generally lower sensitivity than instrumented assays.
Paper vs polymer chips
Use paper for ultra-low-cost, largely qualitative tests; choose thermoplastic or glass chips when you need precise flow control, quantification, or integration with optics and electronics.
Frequently asked questions
What is paper microfluidics?
A class of devices (µPADs) that use patterned hydrophilic channels in paper to wick fluid by capillary action, enabling low-cost, pump-free tests.
Is a lateral-flow test paper microfluidics?
Yes — lateral-flow strips are the most widespread example, moving fluid through a porous membrane by capillary action.
How are paper microfluidic channels made?
By patterning hydrophobic barriers (wax printing, photolithography or cutting) so that fluid is confined to hydrophilic channels in the paper.
What are the limits of paper microfluidics?
Limited fluid control and quantification, evaporation, and generally lower sensitivity than channel-based or instrumented assays.
From paper to production
Need more control than paper allows?
If your assay outgrows paper, we make precise polymer and glass chips. Upload a design for a quote, or book a call.
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