Behind the cover: December 2022
Each month, Physics Today editors explore the research and design choices that inspired the latest cover of the magazine.
According to the Health Resources and Services Administration , 17 people die each day waiting for an organ transplant in the US. Bioprinting, illustrated on the December issue’s cover, is a promising technology for fabricating the needed tissues and organs. But unlike ordinary computer-controlled 3D-printed objects, which are ready immediately after printing, bioprinted objects must undergo additional processes to become ready and sturdy enough for transplantation. In those processes, a machine dispenses bioinks—materials made of cell aggregates. When deposited next to each other, segments of the cellular materials fuse and self-assemble into larger tissue.
In their article on tissue engineering , Ashkan Shafiee, Elham Ghadiri, and Robert Langer describe the physics of the bioinks’ cellular self-assembly process. (That article, alongside one on animals’ manipulation of complex fluids , is part of this month ‘s special focus on physics and biology.) The authors’ and other researchers’ goals are to understand and predict how tissues behave after they are bioprinted. Although scientists have fabricated some organs, such as urethras, vaginas, and bladders—usually from the patients’ own cells—the procedure is still not widely available. Ultimately, researchers aim to create organs that can be integrated into the human body as if they had been there from birth.
Physics Today‘s art director, Donna Padian, found the topic of fabricating human tissue to be image rich. After sorting through options showing 3D printing techniques that produce human hearts, ears, and skin, she chose this computer-designed schematic image of heart tissue fabrication for the December cover. “The setting appears high-tech, and the metal machinery shines, which highlights the novelty of the techniques used in 3D printing,” she says. “It also contrasts nicely with the pink heart.” Padian chose the typeface Atrament for the cover line “Tissue engineering” because of its slightly rounded corners and subtle puffiness. And its color further associates the words with the heart.