STEM at Work: A New Kind of 3-D Printer

While the acronym STEM integrates the disciplines of science, technology, engineering and mathematics, K-12 schools are still designed around subjects that are often carefully fenced-off from one another.  Different subjects live in different departments and tight schedules make it difficult for math and science teachers to collaborate.   STEM-integrated classes are often taught as specials like art and music and schedules during the "regular" teachers' planning periods, making collaboration almost impossible.  

However, in higher education there are great examples of how powerful STEM is when its components are integrated.  

Here is one such story. 

A 3-D printer creates a shape by adding layer upon layer to create a three-dimensional model of nearly anything; that is, so long as the shape is solid and can be built from a firm base.  

But what if a 3-D printer could "draw in the air," creating a network of thin strands such as in the model in the illustration?  

Dr. Rohit Bhargave, the director of the Cancer Center at the University of Illinois in Champaign-Urbana (UICU) and his graduate student Matthew Gelber have designed a 3-D printer to do exactly that.  

Using an alcohol sugar called isomalt as the printing material, their 3-D printer extrudes a thin stream of the sugar that hardens as it comes in contact with the air.  

Dr. Bhargava who began his career by training to be an engineer and now heads the UICU Cancer Center designed the machine to address a research problem that includes both engineering and biological dimensions.  

Cancer cell cultures are studied as they lay on flat dishes, an environment that loses the three-dimensional nature of cells.  The UICU printer provides "a great way to create shapes around which we can pattern soft materials or grow cells and tissue, then the scaffold dissolves away...For example, one possible application is to grow tissue or study tumors in the lab."  

Building the printer required the Illinois team to solve a number of different problems.  They needed a printing material that wouldn't burn or crystallize. They found that the alcohol sugar isomalt met that requirement.  Then they needed to engineer a number of mechanical details, finding the right temperature and pressure under which the isomalt was extruded from a nozzle of the right diameter, as well as the right speed of extrusion so that a stable structure would result.  

Once those problems had been addressed, the team faced the problem of developing the computer software that would translate a design into a sequence of steps that tell the printer how to make the design into a set of intersecting filaments that would not collapse, according to Gelber, who was the first author on the paper in the journal Additive Manufacturing that describes the project. 

The algorithm was designed in collaboration with Wolfram Research, a Champaign company that also created the Website Wolfram Alpha and the software Mathematica.  

Among the advantages of Barghava and Gelber’s work is that the process can create thin tubes with circular cross-sections. “When the sugar dissolves, it leaves a series of connected cylindrical tubes and tunnels that can be used like blood vessels to transport nutrients in tissue or to create channels in microfluidic devices.

Dr. Bhargava and his team have already begun to use the new printer to create scaffolds for microfluidic devices and cell cultures and are developing coatings that will control how quickly the scaffolds dissolve.

See a demonstration of the printer at this link.

A side note: Dr. Bhargava is a professor at the Carle Illinois School of Medicine that claims to be “the first college of medicine in the world specifically designed at the intersection of engineering and medicine. The medical school’s curriculum infuses “engineering, medicine and the humanities to create a truly innovative future centered on the human condition.”
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Resources:
Touchstone, Liz Ahlber (2018). 3-D printed sugar scaffolds offer sweet solution for tissue engineering, device manufacturing. Illinois News Bureau, May 23, 2018
 
Image: Miniature 3-D heart scaffold.

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