Photo: Photo supplied by Dani Clode
A New Zealander at Cambridge University, Dani Clode has built a prosthetic you can wear on your hand - strapping in opposite your thumb, which connects to controls at the feet.
Recent research has found her third thumb was incredibly useable - 98 percent of nearly 600 people who trailed the 'third thumb' successfully operated it and performed a task.
She developed the third thumb to increase the wearer's range of movement and improve grasping capability - extending the carrying capacity of the hand.
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Clode is head designer and senior technical specialist at Cambridge University's Plasticity Lab.
She first came up with the idea doing her Masters in industrial design at the Royal College of Art, she tells Nine to Noon.
"The thumb is really interesting, it's such a uniquely human limb that we have. And it's such a really, it's a really cool kind of movement.
"And also, it's not very well designed on a lot of prosthetic arms I found so I really wanted to hyper focus on the thumb."
Her prosthetic thumb sits next to the pinky, directly opposite the thumb.
The thumb can expand the function of the hand with extra grasping capability and users got the hang of it very quickly, she said.
"People could use it within the first minute, they could grasp an object with it."
More detailed studies using MRI found how the fingers are represented in the hand area of the brain, of the hand that uses the third thumb, became more similar to each other, she said.
"So, we're fundamentally changing the way you're using your hand by adding this extra functional limb onto the hand. And that's super interesting."
The design has been tested on 600 people, children and adults, and 98 percent were able to wear it comfortably, she said.
The thumb is completely 3D printed, she said, allowing materials technology to pushed to the limit.
The main thumb is a flexible, 3D-printed filament made from a material called thermoplastic polyurethane, she said.
"I was really inspired by how the human body works. We don't have any interlocking mechanisms or joints, we've just got ligaments being pushed and pulled very deliberately."
She and her colleagues were now testing the thumb on able-bodied participants, she said.
"People who have just recently broken an arm, based on the testing that we could see that people could use it within the first minute.
"We give crutches for people that have recently broken a leg, but we don't really have any options for people who've just broken an arm."
It has potential applications for stroke patients as well, she said.
"We're looking at potentially controlling the thumb with their more abled arm or able hand or alternatively putting the third thumb on their more restricted arm for more function on that arm."
Augmentation was an under explored branch of prosthetics, she said.
"It's weird and wonderful and I'm just amazed that people are so excited about this weird thing that I made."