lab-on-a-chip
Meaning of lab-on-a-chip: Shrinking a laboratory onto a slide changes the physics as much as the scale, and that is rather the point of it.
Definition of lab-on-a-chip
A lab-on-a-chip is a small plate, often no larger than a microscope slide, patterned with channels finer than a human hair through which droplets of fluid are moved to carry out laboratory tests. Steps that would fill a bench with tubes and pipettes happen in sequence on the one chip. Samples are tiny and results can appear within minutes.
Why does shrinking the channels change the behavior of fluids?
At this scale liquids stop swirling. Flow becomes smooth and layered, so two streams meeting in a channel run side by side without mixing, and blending happens only as molecules gradually wander across the boundary. Surface tension and the pull of the channel walls outweigh gravity, which allows droplets to be steered, split, merged and held in place by the shape of the channel alone. Distances are so short that heating, cooling and reaction steps that take minutes in a test tube finish in seconds. These are not merely conveniences; they are the reason a chip can do things a full-sized laboratory cannot.
What is it used for?
| Task | What the chip does |
|---|---|
| Testing at the bedside | Runs a blood or saliva test where the person is |
| Copying genetic material | Cycles temperatures fast enough to amplify DNA quickly |
| Sorting cells | Separates cell types by size, charge or surface markers |
| Capturing rare cells | Traps the few tumor cells circulating in a blood sample |
| Organ on a chip | Grows living tissue in channels to test drug effects |
Is it the same as a microfluidic device?
Not quite, though the terms are often traded as if they were. A microfluidic device is any device handling minute volumes in narrow channels, a class that takes in inkjet printheads and implanted pumps that release drugs slowly. A lab-on-a-chip is the subset built to perform the steps of a laboratory test from start to finish, which is why it is also called a micro total analysis system. The obstacles are practical rather than theoretical: real samples such as whole blood, sputum or stool are thick and full of debris that clogs fine channels, and the pumps, heaters and readers surrounding the chip are frequently larger and costlier than the chip itself, which limits how far this particular medical device has replaced the bench.
Also known as
Used in a sentence
The clinic evaluated a lab-on-a-chip system for testing samples at the point of care.
Good to know
Lab-on-a-chip and microfluidic device are not synonyms, since microfluidics describes the underlying technology and includes devices, such as inkjet heads and implanted pumps, that perform no analysis at all.