LONDON-An artificial neural network that's made entirely from DNA and mimics the way the brain works has been created by scientists in the lab.

The test tube artificial intelligence can solve a classic machine learning problem by correctly identifying handwritten numbers. The work is a significant step in demonstrating the ability to program AI into man-made organic circuits, scientists claim.

This could one day lead to human-like robots made from entirely organic materials, rather than the shiny metal cybermen seen in popular culture.

Researchers hope the device will soon start forming its own 'memories', from examples added to the test tube. Their ultimate goal is to program intelligent behaviours – such as the ability to compute, make choices, and more – with artificial neural networks made from DNA. Experts at Caltech chose a task that is a classic challenge for electronic artificial neural networks, recognising handwriting.

This was one of the first tasks tackled by machine vision researchers and an ideal method to illustrate the capabilities of DNA-based neural networks

Human handwriting can vary widely, and so when a person scrutinises a scribbled sequence of numbers, the brain performs complex computational tasks in order to identify them.

Because it can be difficult even for humans to recognise one another's sloppy handwriting, identifying handwritten numbers is a common test for programming intelligence into AI neural networks. These networks must be 'taught' how to recognise numbers, account for variations in handwriting, then compare an unknown number to their so-called memories and decide the number's identity. The team demonstrated that a neural network made out of carefully designed DNA sequences could carry out chemical reactions to indicate it had correctly identified 'molecular handwriting.' When given an unknown number, this so-called 'smart soup' would undergo a series of reactions and output two fluorescent signals, for example, green and yellow to represent a five, or green and red to represent a nine.

Lead researcher Lulu Qian, assistant professor of bioengineering, said:  'Though scientists have only just begun to explore creating artificial intelligence in molecular machines, its potential is already undeniable.


 'Similar to how electronic computers and smart phones have made humans more capable than a hundred years ago, artificial molecular machines could make all things made of molecules – perhaps including even paint and bandages – more capable and more responsive to the environment in the hundred years to come.'

Unlike visual handwriting that varies in geometrical shape, each example of molecular handwriting does not actually take the shape of a number.

Instead, each molecular number is made up of 20 unique DNA strands chosen from 100 molecules, each assigned to represent an individual pixel in any 10 by 10 pattern.

These DNA strands are mixed together in a test tube.

Given a particular example of molecular handwriting, the DNA neural network can classify it into up to nine categories, each representing one of the nine possible handwritten digits from 1 to 9.

First, the team built a DNA neural network to distinguish between handwritten sixes and sevens.

They then tested 36 handwritten numbers and the test tube neural network correctly identified all of them.

The system theoretically has the capability of classifying over 12,000 handwritten sixes and sevens – 90 per cent of those numbers taken from a database of handwritten numbers used widely for machine learning – into the two possibilities.