Chips with everything: Lab-on-a-chip

By making everything smaller, more and more things can be crammed into minute devices. Scientists have a vision of a miniature 'laboratory on a chip' that could carry out many experiments at the same time.

One of the products of the miniaturisation trend has been the development of lab-on-a-chip tools: plastic, glass and silicon chips containing complex arrays of channels, pumps and valves that can move minute amounts of fluid and suspended solids.

These highly complex tools incorporate complex chemistry and signalling in a tiny space. Their uses include the separation and analysis of complex mixtures of molecules, miniaturised diagnostic or drug discovery tools, and high-throughput tools for studying gene or protein activity in cells or tissues.

The technological challenges are very great. With very small diameter tubes, for example, water does not flow freely, so moving substances around is very difficult; some groups are experimenting with active transport systems based on the molecules that transport material around cells.

At present, these lab-on-a-chip micro-reactors range from around 10 to 100 µm (10 000–100 000 nm), so are not yet strictly nanotechnologies (generally defined as less than 100 nm). While much progress has been made on different components of the nano-lab-on-a-chip, they have not yet all been combined in a single functioning device. But it is likely that nanoscale chips will become available.

As for the future, there are some encouraging signs, but no really successful products yet. There are certain regulatory hurdles to cross. There would definitely be uses in research, but practical applications would depend on integration into health systems – far from straightforward.