Robot thumb turns everyone into cyborgs – who can peel bananas one-handed

The Third Thumb in action (Pictures: Dani Clode Design/The Plasticity Lab)

Who hasn’t wished they had a spare pair of hands now and again? You might be trying to unlock the front door with your arms full of shopping, or rushing to prep dinner but can only chop so much at a time.

Well, humanity has just taken a step closer with an extra thumb – paving the way for future robotic limbs.

The Third Thumb, designed by Cambridge researchers, is strapped to the hand at the bottom of the palm, below the little finger – opposite the real thumb. It is controlled by a pressure sensor underneath each big toe or foot. Pressure from the right toe or foot pulls the thumb across the hand, while pressure from the left moves it  up towards the fingers.

Releasing the pressure moves it back to its original position.

One of the aims of the thumb is to augment the human body, and one-handed tasks carried out while wearing the prosthetic in testing include peeling a banana, open drinks bottles and playing cards.

The team from Cambridge also said it’s incredibly easy to use, testing the device on almost 600 members of the public at the 2022 Royal Society Summer Science Exhibition.

Over five days, 596 people tried the Third Thumb, ranging in age from three to 96. Only four were unable to operate it, either because it did not fit their hand securely, or in the case of very young children, they were too light to operate the pressure pads.

However, within a minute most people were able to operate the thumb smoothly, and completed tasks including picking up and moving pegs from a board into a basket, then moving objects of varying shapes and sizes into another basket.

The team stressed the importance of testing new technology on a wide demographic, to ensure it worked for everyone.

The aim to enhance the body’s own abilities (Picture: Dani Clode Design/The Plasticity Lab)

Professor Tamar Makin, from the Medical Research Council (MRC) Cognition and Brain Sciences Unit at the University of Cambridge, said: ‘Technology is changing our very definition of what it means to be human, with machines increasingly becoming a part of our everyday lives, and even our minds and bodies.

‘These technologies open up exciting new opportunities that can benefit society, but it’s vital that we consider how they can help all people equally, especially marginalised communities who are often excluded from innovation research and development.’

Examples of bad tech research cited by the university include women facing higher health risks from car accidents because male crash test dummies are used, and speech recognition systems that work better for white voices than Black.

Co-author Lucy Dowdall added: ‘If motor augmentation – and even broader human-machine interactions – are to be successful, they’ll need to integrate seamlessly with the user’s motor and cognitive abilities. 

‘We’ll need to factor in different ages, genders, weight, lifestyles, disabilities – as well as people’s cultural, financial backgrounds, and even likes or dislikes of technology.’

And while for now the thumb is used for relatively simple tasks, it demonstrates the huge potential for robotics to enhance the human body beyond current biological limitations.

Personally, we’re definitely in the market for a tail for extra balance.