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Last Updated: Thursday, 6 May, 2004, 12:32 GMT 13:32 UK
Tiny robot walker made from DNA
Nano walker
The tiny robots are made from the building blocks of life
Scientists have created a microscopic walking robot using only the building blocks of life: DNA.

The tiny walker is only 10 nanometres long and has been described as a major step forward in nanotechnology.

A New York University team created the robot using DNA legs that move along a footpath, which is also based on DNA.

The legs move by detaching themselves from the footpath, moving along it and then reattaching themselves, New Scientist reports.

DNA is an ideal material to build the robot from, because DNA chains easily pair up.

By re-ordering the sequence of base pairs that make up the DNA strand, the scientists were able to control where each strand attached.

"What we've done is to build a sidewalk to accommodate one step and we've demonstrated quantitatively that [the robot] can take a second step," Professor Nadrian Seeman, of New York University, told BBC News Online.

Leg work

Each leg of the biped is made from two strands of DNA paired up as a double helix. These legs are connected by flexible "linker" strands of DNA.

Each leg of the biped has a portion at its end which is single-stranded. The scientists refer to this as a foot, and it is available to pair up with a complementary DNA strand.

Likewise, each domain in the track has a single-stranded region that can pair with a complementary strand. The single strands on the foot and footpath are designed so that they should not generally pair up.

The researchers have to add a strand, called a set strand, which is complementary to both to make the foot attach to the foothold.

To make the walker take a step, the researchers then add another DNA strand called an unset strand to release the foot.

After this, the released foot grabs another set strand and the process can be repeated.

The research has been published in the journal Nano Letters.

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