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New low-cost 3D-printed prosthetic hand will help more amputees

16 May 2017
Biomedical engineering student meets the challenges of disability

The high cost, limited usefulness, poor fit and comfort, and deficient device training for new prosthetic devices mean that many recipients are unable to take advantage of new technologies.

Kristina Mahony holding a prosthetic hand in the lab

University of Sydney biomedical engineering student, Kristina Mahony is working with Dr Justin Bobyn to develop a new 3D-printed abdomen-powered prosthetic hand to address these critical needs.

Kristina was awarded a selective Sydney Industry Project Placement Scholarship (SIPPS) – a unique combination of an honours thesis with project experience – funded by industry partner, Accenture. Supervised by Dr Bobyn, an orthopaedic registrar at Westmead Hospital, Kristina's aim is to create a low-cost mechanical prosthetic device that is more aesthetic than a traditional hook hand.

"We explored alternative methods of control to offer the user more degrees of freedom", says Kristina. "We wanted the hand to be able to be customised to fit so that this would increase functionality and give the recipient a deeper sense of ownership with the device."

Traditional mechanical prosthetic arms are attached to the amputee via a harness system. When the amputee abducts their shoulder a cable on the harness is pulled and the prosthetic grip type is changed, for example from hand open to hand close.

Dr Bobyn and Kristina have designed a harness system which not only compensates for shoulder movements but uses the abdomen and sides to pull different cables, resulting in a wider range of grip patterns and degrees of freedom.

The added bonus will be the potential cost of the new prosthesis.

"Simple upper limb prostheses utilising a mechanical hook offer the most cost effective option. Their function is extremely limited, but they are durable. These may cost upwards of $3000. At the other end of the spectrum are myoelectric limbs with multiple degrees of freedom with a cost of tens of thousands of dollars. They are significantly less durable than their mechanical counterparts and are also limited by their reliance on battery", says Dr Bobyn.

"We propose a limb that can be built by the user for a hundred dollars that offers the durability and dependability of contemporary mechanical limbs, with the freedom of high-end myoelectric limbs."

Currently in prototyping stage, Kristina is working to increase the modularity of the system to allow the user to easily customise the grip patterns of the hand, as well as improve harness comfort and functionality.

"I have always had a passion for maths and science and wanted to apply these skills in a practical way – something with a strong humanitarian focus", adds Kristina. "Biomedical engineering at the University of Sydney has allowed me to think critically, learn about how technology works and hopefully apply these skills to improve the lives of people on a grand scale."