With the growth of additive manufacturing, 3D printing your own prosthetic from models found in open-source databases is possible.
But those models lack personalised electronic user interfaces like those found in costly, state-of-the-art prosthetics.
By integrating electronic sensors at the intersection between a prosthetic and the wearer's tissue, the Virginia researchers say they can gather information related to prosthetic function and comfort, such as the pressure across wearer's tissue, that can help improve further iterations of these types of prosthetics.
The integration of materials within form-fitting regions of 3D-printed prosthetics via a conformal 3D printing technique, instead of manual integration after printing, could also pave the way for unique opportunities in matching the hardness of the wearer's tissue and integrating sensors at different locations across the form-fitting interface. Unlike traditional 3D printing that involves depositing material in a layer-by-layer fashion on a flat surface, conformal 3D printing allows for deposition of materials on curved surfaces and objects.
According to Yuxin Tong, an industrial and systems engineering graduate student and first author of the published study, the ultimate goal is to create engineering practices and processes that can reach as many people as possible.
To develop the prosthetics integrated with electronic sensors, the researchers started with 3D scanning data, in this case a mould of the teenager's limb.
They then used 3D scanning data to guide the integration of sensors into the form-fitting cavity of the prosthetic using a conformal 3D printing technique.
The team tweaked the prototype prosthetic by developing new additive manufacturing techniques that would allow for a better fit to teen’s palm, creating a more comfortable, form-fitting prosthetic device.
They validated that the personalisation of the prosthetic increased the contact between the teen’s tissue and the prosthesis by nearly fourfold as compared to non-personalised devices. This increased contact area helped them pinpoint where to deploy sensing electrode arrays to test the pressure distribution, which helped them to further improve the design.
Sensing experiments were conducted using two personalised prosthetics with and without sensing electrode arrays. By running these experiments with the teen, they found that the pressure distribution was different when she relaxed her hand versus holding her hand in a flexed posture.
"The mismatch between the soft skin and the rigid interface is still a problem that will reduce the conformity," said Tong. "The sensing electrode arrays may open another new area to improve the prosthetics design from the perspective of distributing a better balance of pressure.
"Hopefully, every parent could follow the description from the paper we published and develop a low-cost personalised prosthetic hand for his or her child," Tong concluded.
