Researchers develop novel 3-D printing method for creating patient-specific medical devices

I believe our research is opening a new fron­tier in materials science research.—Joshua Martin, PhD’17

We’ve all seen pic­tures of pre­ma­ture babies in neonatal care units: tiny beings, some weighing just a bit over a pound, with plastic tubes snaking through their nose or mouth, or dis­ap­pearing into veins or other parts of the body. Those tubes, or “catheters,” are how the babies get the nec­es­sary oxygen, nutri­ents, fluid, and med­ica­tions to stay alive. In the United States alone, nearly 500,000 pre­ma­ture babies are born each year.

The problem is, today’s catheters only come in stan­dard sizes and shapes, which means they cannot accom­mo­date the needs of all pre­ma­ture babies. “With neonatal care, each baby is a dif­ferent size, each baby has a dif­ferent set of prob­lems,” says Ran­dall Erb, assis­tant pro­fessor in the Depart­ment of Mechan­ical and Indus­trial Engi­neering. “If you can print a catheter whose geom­etry is spe­cific to the indi­vidual patient, you can insert it up to a cer­tain crit­ical spot, you can avoid punc­turing veins, and you can expe­dite delivery of the contents.”

Erb’s team has devel­oped an inno­v­a­tive 3-D printing tech­nology that uses mag­netic fields to shape com­posite materials—mixes of plas­tics and ceramics—into patient-??specific prod­ucts. The bio­med­ical devices they are devel­oping, which include catheters, will be both stronger and lighter than cur­rent models and, with their cus­tomized design, ensure an appro­priate fit. Their paper on the new tech­nology appears in the Oct. 23 issue of Nature Com­mu­ni­ca­tions.

Back to nature

Others have used com­posite mate­rials in 3-D printing, says Joshua Martin,the doc­toral can­di­date who helped design and run many of the exper­i­ments for the paper. What sets their tech­nology apart, say Erb and Martin, is that it enables them to con­trol how the ceramic fibers are arranged—and hence con­trol the mechan­ical prop­er­ties of the mate­rial itself.

That con­trol is crit­ical if you’re crafting devices with com­plex archi­tec­tures, such as cus­tomized minia­ture bio­med­ical devices. Within a single patient-specific device, the cor­ners, the curves, and the holes must all be rein­forced by ceramic fibers arranged in just the right con­fig­u­ra­tion to make the device durable. This is the strategy taken by many nat­ural com­pos­ites from bones to trees.

Con­sider the struc­ture of human bone. Fibers of cal­cium phos­phate, the min­eral com­po­nent of bone, are nat­u­rally ori­ented just so around the holes for blood ves­sels in order to ensure the bone’s strength and sta­bility, enabling, say, your femur to with­stand a daily jog.

“We are fol­lowing nature’s lead,” explains Martin, PhD’17, “by taking really simple building blocks but orga­nizing them in a fashion that results in really impres­sive mechan­ical prop­er­ties.” Using mag­nets, Erb and Martin’s 3-D printing method aligns each minus­cule fiber in the direc­tion that con­forms pre­cisely to the geom­etry of the item  being printed.

“These are the sorts of archi­tec­tures that we are now pro­ducing syn­thet­i­cally,” says Erb, who has received a $225,000 Small Busi­ness Tech­nology Transfer grant from the National Insti­tutes of Health to develop the neonatal catheters with a local com­pany. “Another of our goals is to use cal­cium phos­phate fibers and bio­com­pat­ible plas­tics to design sur­gical implants.”

Read more: Researchers develop novel 3-D printing method for creating patient-pecific medical devices

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