Category Archives: Blog

David Ruppert’s good work recognized

David Ruppert, a Ph.D. candidate in the NCSU/UNC joint Bio Medical Engineering program, has recently had some of his outstanding work relating to the potential for customized prosthetic implants recognized nationally. To quote from a PR Newswire article published on March 8, 2016 titled “Improving the Lives of Amputees” :

“In the United States, there are hundreds of thousands of amputees caused by trauma alone, and this number is expected to steadily rise as the population continues to grow.  Although socket-type prostheses are the most common, an optimal fit is difficult to achieve, often resulting in painful sores and other complications. Socket prosthetic devices also lack stability due to their inefficient integration with the body. This has led to an increased interest in improving the methods of attaching prosthetic devices to amputees.

One approach gaining popularity is the integration of a prosthetic implant directly with the amputees’ residual bone. This implant penetrates the skin to connect to a prosthetic limb. This direct prosthesis-bone interface allows for a more stable connection to the skeleton enabling greater control of the prosthesis and heightened sensory feedback of the environment while eliminating pain and sores experienced with socket prostheses. Although this type of prostheses offers promise, it is not without issues. “Unfortunately, these implants face several challenges which prevent their approval by the FDA outside of clinical trials,” explains David Ruppert, a researcher at the University of North Carolina at Chapel Hilland North Carolina State University. “The implants need to conform to patients’ specific anatomy; the skin penetration of the implant is susceptible to infection; and a 12 month rehabilitation period is required to produce a stable bone-implant interface.”  Ruppert, along with his collaborators, are currently conducting research focused on addressing the patients’ specific anatomy as well as reducing the lengthy rehabilitation period. “Our findings showed that rough textured implants created though 3D printing exhibit stronger bone integration than machine threaded counterparts,” says Ruppert.  “This highlights the superiority of using 3D printing to not only produce custom designs, but also custom surfaces that interface with amputees’ residual bones.”

There is much more in the article. David’s work was also recognized in 3D Print.Com where the article includes several photos that provide an excellent visualization of what this research is trying to accomplish.

We’re all proud of the work that David has done and continues to do.  This is important stuff, being done by a serious young man and supported by world class faculty leaders.

Successful Day at NCSU’s Vet School Open House

This past Saturday, additive manufacturing made an appearance at the Open House for NC State’s College of Veterinary Medicine. We brought several previously printed models to display, ranging from plastic limbs used for surgery visualization to cobalt chromium prosthetics and titanium implants. However, the main attraction of our set-up was the Makerbot Replicator 2x, with a build in progress of a canine skull.


Many of our visitors had never seen any type of additive manufacturing before and were amazed at opportunities the field presents. Although we have partnered with the NC State’s Vet School for many years, many doctors who had not previously been aware of our capabilities expressed interest in future collaboration.  Our visibility there has helped us reach out to a large percent of the estimated 10,000 visitors that attended the event.


Human Exoskeleton Developed Using 3D Printing

In a collaborative effort between 3D Systems and EksoBionics, an exoskeleton was developed using 3D printing technologies to give paraplegics, such as Amanda Boxtel, the ability to walk on their own again! The exoskeleton that was designed for Boxtel exemplifies how additive manufacturing allows for highly individualized design of assistive devices that are rigid and lightweight. This groundbreaking advancement will not only have an impact on the medical industry, but it will affect the lives of the thousands of paraplegics and their families!

See the link here:

Custom Titanium Horseshoes through Additive Manufacturing

Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has applied additive manufacturing toward helping horses run better. With custom shoes, horses can enjoy a better fit to their hooves with less weight slowing them down. This application of additive manufacturing will not only have an impact on horse sports, but will also allow veterinarians to treat hoof problems through therapy with corrective shoe designs.


Update on Augie The Green Sea Turtle

If you recall from the post last fall (Link Here), Augie was rescued off of the coast of North Carolina with an open fracture of his right flipper.   Through the NC State College of Veterinary Medicine, (Dr. Craig Harms, Dr. Marcellin-Little & Dr. Emily Christiansen) we collaborated with the NC Aquarium at Roanoke Island (Dr. Christian Legner) and the Network for Endangered Sea Turtles (NEST) to design and fabricate a custom fit splint to stabilize the injury while Augie healed.  The splint was fabricated on our Objet Connex 350 using Vero-Clear material and we also made a back-up brace with the ABS-like material.   The fit of the brace to the flipper was tested on a model of the flipper, also made on the Objet Connex 350 with Tango-Plus material representing the soft tissues and Vero-White material for the bones.

turtle-flipper-3d-printed-multi-materials-brace-installed-01 turtle-flipper-3d-printed-multi-materials-01
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Improving Reliability and Consistency of 3D Printers

Being a research based university, we are constantly presented with different projects requiring us to build parts on the “low end” 3-D printers.  Normally this is not an issue but occasionally we have to make modifications to the printers to ensure we meet our goals.  This became a hassle because we would constantly have to monitor the printers and make manual adjustments to attempt to finish prints.  To overcome this obstacle, we designed a heated enclosure to encompass our 5 most commonly used printers.

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3D Printing an Argon Diffuser for Heat Treatment of DMLS Parts

DMLS (Direct Metal Laser Sintering) parts require heat treatment after building to relieve thermal stresses induced in the process. These stresses cause parts to warp and curl if they are removed from the building platform without heat treatment. The following picture is an example of how the thermal stresses can affect parts without heat treatment.

DMLS curl
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EBM Produced Copper & Aluminum Network Structures

One of the more interesting possibilities enabled by additive manufacturing is the fabrication of engineered cellular structures designed to dissipate energy in collisions.   Metal foams for energy dissipation have been studied for quite some time.  These structures are often made by injecting gases into molten metal as it solidifies or depositing metal onto a preexisting scaffold.  In many cases the mechanical properties of these structures are difficult to control with precision.

121813 blog Figure 2

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3D Printed External Brace for Sea Turtle Flipper

We were recently contacted about fabricating a custom brace for a Green sea turtle (Chelonia mydas) with an open fracture sustained to the  right radius and ulna with a large wound on the ventral aspect. The fracture was continuous with partially healed lacerations of the skin. The turtle was found by members of the public off Carrot Island and turned over to the Coast Guard. 

IMGP3589The Injury to the right front flipper was severe, but the entire flipper appeared to have viable blood flow and nervous function, making salvage of the limb a good possibility. Surgical stabilization of the fractures may have be an option  but traditional reduction did not appear to be a practical solution, so we accepted this challenge as a unique opportunity to apply additive manufacturing techniques due to the irregular shape of the flipper as well as the urgent nature of the case. We received CT scans of the turtle which included both the broken and intact front flippers. We reconstructed these scans into 3D models using Mimics software. Continue reading

Improving the Surface Finish of Parts Made With Thermoplastic Extrusion Part 2: Preliminary Tensile Testing Results

     In continuation of my first post on this subject, the first three of tensile specimens were put to the test this past week. With the assistance of Dr. Harvey West, I subjected the specimens to a tensile test until failure. For the set up I chose to apply a 0.1 in/min displacement of the load. I also used a 5000 lb capacity load cell to withstand the loads I wished to apply and a universal joint to compensate for any warping that might have occurred in previous steps.(i.e. in the printing process or in the acetone bath)

Before TestDuring Test

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Mechanical Validation of Composite Femurs for Testing Patient Specific Implants

The study I am working on is a sister study to one published last year:

Little JP, Horn TJ, Marcellin-Little DJ, et al. Development and validation of a canine radius
replica for mechanical testing of orthopedic implants. Am J Vet Res 2012;53:27-33.

The focus of the study that I am involved in is the construction of canine femur replicas to
be used for the mechanical testing of orthopedic implants. Continue reading

Improving the Surface Finish of Parts Made With Thermoplastic Extrusion

While exploring several ways to improve the surface quality of parts off of 3D printers, Dr. Dennis Cormier, who now works at RIT, suggested that acetone vapors could be used to give parts a glossy finish with just a rice cooker and some acetone. After reading more 3D printing forums and acquiring the necessary material I discovered that this method actually worked! Below is a short video of the process (at 2x speed).  This got me thinking. With 3D printing (additive manufacturing) becoming more predominant in the fabrication of functional end use components, could this method do more?

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