Researchers in Japan have developed an electrical sensor that can tell apart the mirror-image forms of amino acids one molecule at a time, a step that could one day help instruments searching for signs of life beyond Earth.

Amino acids, the building blocks of proteins, come in left-handed and right-handed forms. Living organisms on Earth use almost exclusively the left-handed form, while nonliving processes produce both in equal amounts. That difference makes the ratio of the two forms a potential sign of life.

The team at the University of Osaka used a nanogap tunneling technique: molecules pass through a gap between two gold nanowires, and each passage produces a distinct electrical current. Combined with artificial intelligence, the system distinguished the two forms with more than 80 percent accuracy.

The researchers tested the method on complex natural samples, including the Murchison meteorite in Australia and soil from Chile's Atacama Desert. The results are published in Nature Communications. "This is the first discrimination of amino acid chirality at the single-molecule level," said lead author Takahito Oshiro.

Reporting based on: phys.org, www.robodaily.com.