Case Study

“In all cases, whether it be FDM or SL rapid prints, QuantumCast parts, molded foam parts or molded urethane parts, Stratasys Direct Manufacturing was instrumental in advising on the manufacturing approach to meet our functional needs.”

It’s not a feat easily undertaken to create a model that simulates breathing, heart rate and childbirth; essentially, the model is a fully articulated machine replicating in a test environment the exhaustive physical complications a mother and fetus experience in the delivery room. The team at CAE undertook a task that would require a simulator made of hundreds of considerably involved components. “The design of the human patient simulator is a complex endeavor requiring extensive validation of the components and in particular the interaction of the physical parts,” explains Giuseppe Mallaci, Senior Mechanical Designer for the CAE Fidelis™ Maternal Fetal Simulator at CAE Inc. “The complexity increases as we introduce moving parts and deformable components in a confined space. Small incremental changes are required to validate such a complex design. The competitive nature of our industry fuels a growing need for relatively short product development cycles – rapid prototypes are essential to the success of any product development initiative.”

CAE used rapid prototyping processes from Stratasys Direct Manufacturing Inc., including Fused Deposition Modeling (FDM), Stereolithography (SL), Laser Sintering (LS), QuantumCast™ cast urethanes and rapid machining. “Stratasys Direct Manufacturing was instrumental in responding to our needs for timely prototypes and subsequently responding to our need to make changes,” says Mallaci. “In all cases, whether it be FDM or SL rapid prints, QuantumCast parts, molded foam parts or molded urethane parts, Stratasys Direct Manufacturing was instrumental in advising on the manufacturing approach to meet our functional needs.” The interlocking and interacting components were in part accomplished by these advanced and rapid manufacturing processes to culminate in a fully functional, incredibly true-to-life simulator.

Mallaci details the critical components for the Maternal Fetal Simulator development:

• Airway – complex molded part.  Complex geometry and deformable.  Required UV stability and must be resistant to abusive user interaction in the form of oral intubation using medical airway adjuncts.
• Ribcage – flexible/deformable body to accurately represent the anatomical features while deforming in a realistic fashion.  Subject to much user abuse when CPR is performed.
• Articulations – the MFS simulator has extensive articulations to best mimic the human body articulations.  In order to validate the articulations as well as the cable management and component placement, it was imperative to have physical prototypes.
• Head assembly – the head assembly consists of many small parts in a confined space.  The rapid prototypes were instrumental to validate the design for manufacturability and assembly purposes.

The original Maternal Fetal Simulator was introduced to an audience of healthcare simulation experts as a fully 3D printed model in June 2013. It was completely outfitted with an internal fetus, visible through a clear 3D printed wall using Stereolithography (SL) with Accura 60 material. SL creates parts in a vat of liquid resin. The resin is cured in patterns via a UV laser, whose energy is directed via dynamic mirrors. As each pattern is completed the build platform within the resin moves down in imperceptible increments, making way for the next layer to cure. This continues, and similarly so in other 3D printing technologies, until the final product is achieved.

The MFS model received articulated legs and arms via Laser Sintering (LS), a 3D printing process which seamlessly lends itself to intricate geometries. The other half of the MFS model required a special process termed ID-Light™ offered solely by additive manufacturing company Stratasys Direct Manufacturing – who provided the entire show model – to incorporate such a large unit devoid of visible seams while resembling skin. ID-Light is a specialized 3D printing process which takes the basic principle of the SL process and reinforces the part with a proprietary inner lattice-like structure, allowing huge parts to be built at what is often 1/12th the weight of solid models.

The final simulator, an amalgam of technologies, was introduced as a functioning training unit this May. QuantumCast™ cast urethanes became a standard rapid production solution for the final model. “Every now and then, there would be a highly complex part that required CNC machining,” explains Sheryl Regalado, Project Engineer at Stratasys Direct Manufacturing. “Jaime, our anatomical models specialist, would work on a design and present it to CAE for cost savings and manufacturability.” QuantumCast works via a soft tool, to save on costs, and machined or 3D printed master patterns. The tool is injected with advanced formula polymer polyurethanes and subjected to heat and pressure to result in a strong and accurate final part. The 3D printed and other rapidly produced parts will serve the development of future simulators as well, according to Mallaci.

“In addition to design and fabrication validation, the rapid prototype parts were also used extensively for validation with our subject matter experts who rely on having fully functional simulators,” says Mallaci. “These simulators must represent the manufacturing intent and consist all of the electronic components, firmware and software. It is inevitable that changes come at every validation gate. Rapid prototype parts are essential to minimize development costs.” The utilization of 3D printing, cast urethanes and advanced axis CNC machining afforded the MFS with organic shapes. The simulator exhibits waist, hip, thighs and pelvic tilt articulative maneuvers and responds to pressures and exercises doctors would be required to undertake during actual childbirth.

The Lucina simulator executes multiple childbirth procedures and scenarios, including: Normal delivery, instrumental vaginal delivery, fetal tachycardia due to maternal pyrexia, breech delivery, fetal central nervous system depression by narcotics given to mother, shoulder dystocia, major post-partum hemorrhage due to uterine atony, maternal cardio-respiratory arrest, eclampsia and umbilical cord prolapsed. These simulations were chosen in part based on the most common childbirth experiences to give an adequate range of training to doctors and nurses.

The simulator is equipped with an electronic monitoring system to display the physiological data of the fetus as well. The entirety of the MFS is meant to give the closest real-life practice, just one step removed from an actual human being. The software (or user interface) additionally emits the cry of the baby, and other sounds from the birthing room, for full sensory bombardments doctors will encounter. The operations the MFS completes provides well-rounded training and preparedness. The simulator is currently being received by hospitals, universities and training facilities throughout the US and Canada.