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Perfect Partners: 3D Printing and Computer Simulation

By Steve Levine Sr. Director of Human Virtual Modeling, Dassault Systèmes

Surgeries can be scary events. The fear over what will happen while in the operating room is compounded by complicated medical jargon during consultation, leaving the patient and their family more uncertain than before. Fortunately, surgeons, such as Dr. David Hoganson of Boston Children’s Hospital, can now demystify the process, walking patients through their upcoming procedures using models of their own bodies.  Combining virtual reality and 3D printed replicas of body parts, the patient as well as the entire surgical team can be prepared.

A multi-physical simulation showing the interaction of mechanical, electrical and fluid properties of the human heart. (All images provided by Dassault Systemes)

Improving the surgical experience is just one example of how 3D printing is fundamentally changing medicine for the better. Another is creating lightweight, lower-cost and often personalized prosthetics. After losing a leg in a snowmobiling accident, paralympian Mike Schultz used 3D printing to develop the Moto Knee, Alpine Foot, and other high-performance sporting prosthetics. Custom printed implants from skulls to heart valves are making personalized medicine a reality. Countless other 3D printing success stories can be told about product designers and medical researchers who have recognized the power of this relatively new manufacturing technology to improve lives. 

Beyond Printing

And yet, 3D printing is a catalyst for an even larger transformation. Once freed from the confines of traditional manufacturing techniques, advanced software tools capable of simulating performance are needed to guide designs of what are often entirely novel products. This became painfully evident during the COVID-19 pandemic, when small changes in performance could mean the difference between life and death. For example when manufacturers wondered whether 3D-printed personal protective equipment (PPE) would be effective against the airborne pathogen. Rather than laborious and risky trial-and-error, SIMULIA PowerFLOW simulation software from Dassault Systèmes was used to create computational simulations of sneeze scenarios to test whether their designs were sound.

Such simulation capabilities are nothing new. The aerospace industry, for instance, has been using computational fluid dynamics (CFD) and finite element analysis (FEA) software for decades. However, when 3D printing began gaining traction for aircraft and satellite components, designers once again turned to simulation software for answers to a whole new set of questions. This accelerated the development of generative design and AM-capable software such as the 3DEXPERIENCE platform from Dassault Systèmes, which supports the unique demands of the entire 3D printing manufacturing process from concept to finished part. 

We will all be the beneficiaries of this work. The medical community does not have the legacy expertise to lead in the creation of these software tools, but they clearly have the need and awareness to participate in its use. Critical data such as material models and operational loads for the human body are now available to designers and researchers as are the tools to create the geometric models. With high reliability, they can simulate how vascular stents, heart pacemakers, dental and orthopedic implants, and hundreds of other components will perform in the human body. With the benefit of these tools, designs can be optimized based on a deep understanding of the mechanics of the human body and even accelerate aging studies before putting them into practice, often as 3D printed products.

The Virtual Twin

So powerful have these simulation tools become that a new term has arisen: the virtual twin. A highly accurate virtual representation of a physical object, the virtual twin can be used for everything from connected vehicle design and smart city development to the optimization of plant floor layouts and associated manufacturing processes. And nowhere is the virtual twin more revolutionary than in its role in representing you, as demonstrated through the Living Heart Project.

The Living Heart reproduces the natural beating of a human heart at rest or exercise, and can be used to simulate blood flow, disease conditions or determine how drugs will effect important conditions such as arrhythmias.

A collaborative effort between Dassault Systèmes, the United States Food and Drug Administration (FDA), and dozens of universities and medical institutions, the Living Heart Project has taken a century of cardiovascular knowledge previously scattered throughout the world and captured it in the first virtual twin of the human heart. This now offers researchers, developers and physicians the opportunity to analyze patients’ cardiovascular systems in silico.  More importantly, it provides the most critical processes in medicine, visualization, comparison, and collaboration. Through simulation, they can better understand the problem and devise and test new drugs and medical devices and share ideas with other experts. They can predict what will happen during a surgical procedure and better anticipate the heart’s reaction to changes. Costs are reduced, medical device development, testing and approval becomes faster, and most importantly, patient outcome is improved.

Companies like Biomodex are taking the digital twin concept one step further. A participant in Dassault Systèmes’ 3DEXPERIENCE Lab program since 2015, Biomodex leverages advanced simulation software together with 3D imaging to develop patient-specific virtual twins of human hearts, valves and blood vessels. They use the behavior prediction from simulation to produce prints that respond identically to the real organ. They can be used within one of the company’s “rehearsal” devices or used in a manner similar to that of the Living Heart Project, giving practitioners a chance to study and learn without relying on animal tissues, cadavers, or mechanical models.

Generative Success

The 3D printing of organs and similarly complex structures requires design, simulation, and optimization software able to cope with variabilities inherent to such geometries. Although not new techniques, for this purpose they must be unified into a single, easy-to-use environment. Done properly, once the optimized design has been simulated and approved, it can then be prepared for printing.

A finite element mesh model of The Living Heart simulation.

The challenge is that the 3D printing process generates its own unique unknowns. Unlike subtractive manufacturing, where material is removed from a billet or casting, AM builds parts from scratch. Like nature itself, this “growth” can lead to distortion during the build process, residual stresses, and microstructure defects, all of which should be accounted for before pushing the print button. Fortunately, the software tools that have been developed for robust product designs can be applied to the build process, eliminating potential problems before they can begin. This is great news for medical device companies, or for that matter, any design and manufacturing firm that uses 3D printing.

Given all of this cutting-edge technology, it’s only logical to ask, “What’s next for the Life Sciences?” Since we can scan human organs, muscles and bones, simulate their behavior and 3D print anatomically accurate replicas, can we use that same technology to manufacture replacement parts, even ones made of living tissue? Can we use our virtual twin to create a physical twin, or at least parts of it?

It’s an exciting concept and one that many in the industry suggest will become a reality within the next decade or so. For example, biotechnology startup Cellink, a Dassault Systèmes’ customer and participant in the 3DEXPERIENCE Lab program, has already developed bio-inks for use in printing liver, cartilage, and skin tissues and even human hearts are in the works. It is the simulation software discussed here that allows them to predict how these materials will behave once printed and to adjust their 3D models and manufacturing processes accordingly.

All of these programs and initiatives show that health care is just beginning to learn the potential presented by removing the physical divide between humans and the machines that improve our lives. As these divides are erased, the winners will be those who are developing their capabilities now to embrace this reality and lead the way. At Dassault Systèmes, we are excited to be offering the platform technologies to create the necessary ecosystems now. I can only begin to imagine what they will do with it, and I can’t wait to see.

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