What Is a Microfluidic Chip? How They Work and How They're Made

What is a microfluidic chip?

A microfluidic chip is a compact device containing channels with cross-sections typically tens to hundreds of micrometres across — small enough that a chip the size of a credit card can hold a complete fluidic circuit. Liquids are introduced through ports, guided through the channel network to be mixed, split, reacted or measured, and then collected or sent to a detector.

Chips are sometimes called lab-on-a-chip devices when they integrate several laboratory steps, or microfluidic cartridges when packaged for a diagnostic instrument. If you are completely new to the field, start with our overview of what microfluidics is.

The anatomy of a microfluidic chip

Most chips share a few common features:

• Substrate and lid — the chip is usually built from two layers: a base with the channels formed into it, and a flat lid bonded on top to seal them.
• Channels — the micro-scale conduits that carry fluid. Their width, depth and shape set the flow resistance and behaviour.
• Inlet and outlet ports — holes where tubing or pipette tips connect to introduce and remove fluid.
• Reservoirs and chambers — wider regions for holding, reacting or storing fluid.
• Functional features — mixers, droplet junctions, filters, valves and optical detection windows.

How do fluids move through a chip?

Fluid can be driven through a chip in several ways:

• Pressure-driven flow — an external syringe pump or pressure controller pushes liquid through the channels. This is the most common method in the lab.
• Capillary flow — surface tension wicks liquid through the channels with no pump, the principle behind many lateral-flow and point-of-care tests.
• Electrokinetic flow — an electric field moves fluid or charged molecules, used in some analytical separations.

Because channels are so small, flow is laminar and predictable. Our guide to the basics of microfluidics explains why — and designers use that predictability to engineer precise behaviour.

Common chip designs and components

A few building blocks appear again and again:

• Straight and serpentine channels — for transport, and for adding length to allow time for reactions or mixing.
• T- and Y-junctions — where two streams meet, used to combine reagents or to generate droplets.
• Droplet generators — junctions that pinch one liquid into another to form thousands of uniform droplets.
• Micromixers — herringbone grooves or zig-zag paths that fold streams together to speed up diffusion-based mixing.
• Gradient generators — branching networks that create a range of concentrations across a chip.

You can size many of these features with our free lab tools — for example channel dimensions, pressure drop and droplet volume.

What are microfluidic chips made from?

The choice of material shapes both performance and how the chip is manufactured:

• PDMS — a soft, transparent silicone that is quick to cast for prototypes and gas-permeable (useful for cell culture).
• Thermoplastics (COC, COP, PMMA, polycarbonate, polystyrene) — rigid, optically clear and ideal for high-volume injection moulding. See our COC vs COP vs PMMA guide.
• Glass — superb chemical resistance and optical clarity for demanding analytical applications.

How are microfluidic chips made?

Manufacturing methods span the full journey from one-off prototype to mass production:

• Soft lithography / PDMS casting — liquid PDMS is poured over a patterned mould and cured; fast and inexpensive for research.
• 3D printing — prints channel structures directly from a CAD file, the quickest route to a testable part.
• CNC micromachining — cuts precise channels into thermoplastics; excellent for pilot volumes and for validating a design before tooling.
• Hot embossing and injection moulding — press or mould channels into thermoplastic at scale, the route to thousands or millions of identical chips.

Sealing the chip: bonding

Once channels are formed, the chip must be sealed with a lid. Common bonding methods include thermal (diffusion) bonding, plasma bonding (especially for PDMS and glass), adhesive bonding and solvent bonding. The right method keeps channels leak-free without clogging or contaminating them — we use solvent- and adhesive-free thermal diffusion bonding where channel integrity matters most.

From a single chip to thousands

The same design often travels from a PDMS or 3D-printed prototype, through CNC-machined validation parts, to injection-moulded production. Choosing a manufacturing partner who can support the whole path avoids costly redesigns. We explain this in custom microfluidics from prototype to scale.

Frequently asked questions