Third thumb: what is it, how does it work and is it easy to use?

Thumbs up will never be the same again 👍
  • Scientists have invented a robotic third thumb.
  • It is wearable and is controlled with your feet.
  • Third Thumb is expected to be able to improve users range of movement.

Have you ever found yourself wishing that you could have an extra finger or thumb? Perhaps while trying to hold an arm full of groceries in the shop and desperately hoping you won’t drop them. 

If you answered yes to that very specific question, then boy do we have good news for you! Boffins at University College London and University of Cambridge have developed a wearable robotic prosthetic thumb and is surprisingly simple to get the hang of. 

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It might sound like pie-in-the-sky thinking from a science fiction film, but development has been underway on the Third Thumb for years. And members of the public have already had the chance to get their hands (and thumbs) on it. 

What is a third thumb? 

Dani Clode

To put it simply it is a wearable robotic prosthetic which gives users an extra thumb to play with. It is worn on the opposite side of the palm to a biological thumb. 

Users control it through a pressure sensor placed under each big toe or foot. If you put pressure on the sensor with your right toe it pulls the thumb across the hand, while using your left toe pulls the thumb up toward the fingers. 

How much the thumb moves is proportional to the pressure applied by your toes, giving users plenty of flexibility when wearing it. To return the thumb back to its original position simply release the pressure. 

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The researchers behind the gadget took MRI scans of wearers and found their brains had changed to accommodate processing of the third thumb. They believe their findings could change the way people view prosthetics and be a first step towards futuristic cyborg-like body augmentation. 

The third thumb is the work of researchers from the University College London (UCL) Institute of Cognitive Neuroscience and designer Dani Clode, who began developing the device, called the Third Thumb, as part of an award-winning graduate project at the Royal College of Art. 

What use does a third thumb have? 

Dani Clode / SWNS

It is hoped that the robotic thumb will help to increase users range of movement as well as enhance their grasping capability when picking up items and expanding the carrying capacity of the hand. University of Cambridge says that this will enable wearers to perform tasks that might be otherwise challenging or impossible to complete with one hand or to perform complex multi-handed tasks without having to coordinate with other people.

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.

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"To ensure everyone will have the opportunity to participate and benefit from these exciting advances, we need to explicitly integrate and measure inclusivity during the earliest possible stages of the research and development process."

How easy is it to use one? 

The third thumb was tested out on members of the public at the annual Royal Society Summer Science Exhibition in 2022. People of all ages were able to give the gadget a whirl and the results have been published in Science Robotics.

The University of Cambridge on its website explained: “Over the course of five days, the team tested 596 participants, ranging in age from three to 96 years old and from a wide range of demographic backgrounds. Of these, only four were unable to use the Third Thumb, either because it did not fit their hand securely, or because they were unable to control it with their feet (the pressure sensors developed specifically for the exhibition were not suitable for very lightweight children).

“Participants were given up to a minute to familiarise themselves with the device, during which time the team explained how to perform one of two tasks. Almost everyone was able to use the device straightaway. 

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Dani Clode / SWNS

“98% of participants were able to successfully manipulate objects using the Third Thumb during the first minute of use, with only 13 participants unable to perform the task. Ability levels between participants were varied, but there were no differences in performance between genders, nor did handedness change performance – despite the Thumb always being worn on the right hand.”

Creator Dani Clode said: “Augmentation is about designing a new relationship with technology—creating something that extends beyond being merely a tool to becoming an extension of the body itself.

"Given the diversity of bodies, it's crucial that the design stage of wearable technology is as inclusive as possible. It's equally important that these devices are accessible and functional for a wide range of users. Additionally, they should be easy for people to learn and use quickly."

If you want to learn more about the public test of the Third Thumb, you can read the published paper in Science Robotics here. Would you be willing to wear a robotic thumb? Let us know!

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