An assistant professor in industrial systems and engineering from Virginia Tech and a team of undergraduate students are hoping to advance customized 3D printed prosthetics with the integration of electronic sensors. The project aims to make sophisticated, electric-powered prosthetics more accessible than existing state-of-the-art prosthetics.
The research project, led by assistant prof Bake Johnson, marks a step ahead in the evolution of 3D printed prosthetic systems by improving their functionalities through the integration of sensors. The sensors in question are placed at the intersection of the prosthetic and the wearer’s tissue and are capable of gathering information related to comfort—including the pressure across the wearer’s tissue—and function. Data from the sensors can lead to further improvements in the prosthetics.
An interesting aspect of the research project is that it uses a conformal 3D printing technique, which entails depositing materials on curved surfaces and objects rather than a flat build plate. This technique has enabled the researchers to integrate materials within form-fitting regions of the 3D printed prosthetics (instead of assembling them manually after printing). This approach could open up opportunities in matching the hardness of the wearer’s tissue as well as integrating sensors at various locations around the form-fitting interface.
In creating the sensor-equipped prosthetics, the first step is 3D scanning the wearer’s limb. In their research, the team used a mold of teenager Josie Fraticelli’s hand. Fraticelli, the daughter of one of Johnson’s colleagues, was born with an underdeveloped right hand caused by amniotic band syndrome.
With the 3D scan data, the researchers were able to integrate the sensors into the form-fitting cavity of the custom prosthetic using a conformal 3D printing technique. As Johnson explained: “Personalizing and modifying the properties and functionalities of wearable system interfaces using 3D scanning and 3D printing opens the door to the design and manufacture of new technologies for human assistance and health care as well as examining fundamental questions associated with the function and comfort of wearable systems.”
In developing the electric-powered 3D printed prosthetic, Johnson and his team worked closely with Fraticelli to make the prototype as comfortable as possible and to optimize the fit. The customized device ultimately increased the contact between her tissue and the prosthetic by nearly fourfold compared to standard devices. The additional contact area made it possible to identify where to deploy sensing electrode arrays to test pressure distribution, enabling them to further refine the design.
“The mismatch between the soft skin and the rigid interface is still a problem that will reduce the conformity,” said Yuxin Tong, an industrial and systems engineering graduate student and first author of the published study. “The sensing electrode arrays may open another new area to improve the prosthetics design from the perspective of distributing a better balance of pressure.”
From Fraticelli’s perspective, the custom 3D printed prosthetic has improved her comfort level though there is still room for improvement, largely due to the simple fact that her hand is soft and moveable while the prosthetic material is rigid. Johnson and his team will continue their research and aim to further improve customized bionic devices.