“Can we make you handkerchiefs made of you?” asked Jennifer Lewis ScD ’91 during MIT.nano’s Mildred S. Dresselhaus 2025 Lecture on November 3. “The main goal of the challenge is to create these tissues for therapeutic use and ultimately at the scale of whole organs.”
Lewis, Hansjörg Wyss Professor of Bio-Inspired Engineering at Harvard University, is taking on this challenge with advances in 3D printing. In her lecture presented both in person and virtually to over 500 attendees, Lewis shared work from her lab that focuses on enhanced functions of 3D printed components for operate in gentle electronics, robotics and life sciences.
“The way a material is made affects its structure and properties,” Lewis said. “This perspective was a breakthrough moment for me because it allowed me to think about 3D printing beyond just prototyping and creating shapes, but about the ability to control local composition, structure and properties at multiple scales.”
Lewis, a materials scientist by training, was considering learning to speak the language of biologists when she joined Harvard to start her own lab focusing on bioprinting and biological engineering. How do particles and polymers compare to stem cells and extracellular matrices? She explained that the key commonality is the need for a material that can be deposited and then removed, leaving the channels open. To meet this need, Lewis’ lab has developed up-to-date 3D printing methods, sophisticated print head designs, and viscoelastic inks, which means the ink can change from a liquid to a solid.
Showing a video of a moving robot octopus named Octobot, Lewis showed how her group developed two sacrificial inks that change color from liquid to solid when heated or cooled. The concept draws inspiration from nature – plants that dynamically change in response to touch, featherlight, heat and hydration. For Octobot, Lewis’ team used sacrificial ink and a built-in printing process that allows free-form printing in three dimensions, rather than layer by layer, to create a fully gentle, autonomous robot. An oscillating circuit in the center directs fuel (hydrogen peroxide), causing the arms to move up and down as they fill and deflate.
From robots to engineering entire organs
“How can we use shape change in tissue engineering?” asked Lewis. “Just as our blood constantly flows through our body, we can have a constant flow of healing.”
Lewis’ lab is currently working on building human tissues, primarily heart, kidney and brain tissue, using patient-specific cells. The motivation, Lewis explained, is not only the need for human organs for ill people, but the fact that receiving an organ from a donor means taking immunosuppressive drugs for the rest of your life. If the tissue could instead be made from your own cells, it would fit your own body better.
“Just as we did in constructing viscoelastic matrices for embedded printing of functional and structural materials,” Lewis said, “we can harvest stem cells and then use our sacrificial writing method to write in a permeable vascular system.” This process uses a technique Lewis calls SWIFT – sacrificial writing in functional tissue. Sharing laboratory research, Lewis showed how stem cells, differentiated into the building blocks of the heart, initially beat individually, but when placed in a tighter space that will support SWIFT, these building blocks fuse together and become one tissue that beats in synchrony. Her team then uses gelatin ink, which hardens or liquefies with changes in temperature, to print the convoluted design of human vessels, washing out the ink, leaving the featherlight open. The channel remains open, mimicking a network of blood vessels in which fluid can actively and continuously flow. “We intend to extend this method not only to different tissue types, but also to introduce mechanisms by which we can build a multiscale vascular system,” Lewis said.
In memory of Mildred S. Dresselhaus
In closing, Lewis reflected on the positive impact Dresselhaus has had on her own career. “I want to dedicate this [talk] “to Millie Dresselhaus,” Lewis said. She pointed to Millie’s quote: “The best thing about having a female professor on campus is that she tells female students that they can do it too.” Lewis, who came to MIT as a materials science and engineering graduate student in the tardy 1980s, when there were very few women with PhDs in engineering, noted that “just seeing someone her height was truly an inspiration to me. I thank her so much for everything she did, for being an incredible inspiration both as a student, as a faculty member, and now, today.”
After the lecture, Lewis was joined by Ritu Raman, Eugene Bell Career Development Assistant Professor of Tissue Engineering in MIT’s Department of Mechanical Engineering, for a question and answer session. The discussion included ideas for hardware and software for 3D printing, tissue repair and regeneration, and bioprinting in space.
“Both Mildred Dresselhaus and Jennifer Lewis have made incredible contributions to science and have been inspiring role models for many in the MIT community and beyond, including me,” Raman said. “In my career as a tissue engineer, the tools and techniques developed by Professor Lewis and her team have provided critical information and enabled the research conducted in my lab.”
This was the seventh Dresselhaus Lecture, named in honor of the tardy MIT Professor Mildred Dresselhaus, known to many as the “queen of carbon science.” The annual event honors a significant figure in science and engineering from anywhere in the world whose leadership and influence reflect the life, achievements and values of Dresselhaus.
“Professor Lewis exemplifies in many ways the spirit of Millie Dresselhaus,” said MIT.nano director Vladimir Bulović. “Millie’s groundbreaking work is indeed well-known, and Professor Lewis’ groundbreaking work in 3D printing and bio-inspired materials continues that legacy.”