HEMI Fellow Sung Hoon Kang Discusses 4D Printing

If you’ve ever watched a child rocket past one shirt size after another, you know that while kids grow, their clothes do not. This underscores a basic difference between living tissue, which grows over time, and dead or engineered materials, which don’t. But what if they did? Imagine a child’s shirt that expanded with its wearer, eliminating the need to buy a new one with every growth spurt.

Sung Hoon Kang, an assistant professor of mechanical engineering, is applying that concept to build 3D-printed cardiovascular implants that can change shape to keep up with the growth of their newborn recipients. He and his colleagues call the process 4D printing, with the fourth dimension being time, and Kang says it has the potential to save both lives and money by eliminating the need for multiple replacement surgeries.

Deadly defects

Congenital heart defects affect nearly 1 percent of all babies born in the United States and are a leading cause of defect-related infant illness and death. Many of these conditions—including tetralogy of Fallot, which was first corrected surgically at Johns Hopkins in 1944—prevent the heart from pumping blood to the lungs, where it absorbs the oxygen needed throughout the body. Doctors can fix this by suturing a small conduit, or tube, between the right ventricle and the lungs during open-heart surgery. It’s a traumatic, risky, and expensive procedure.

At present, these conduits are made of synthetic materials, such as Gore-Tex, or from harvested tissue. And though they can last for years, all share the same basic limitation: They can’t get any bigger. “As time goes on, the infant outgrows the implant,” Kang says.

When that happens, the conduit must be replaced, often more than once and sometimes under emergency conditions. That means more open-heart surgeries. According to the Centers for Disease Control and Prevention, hospitalizations for congenital heart defects cost $6.1 billion in 2013.

Origami to the Rescue

Inspired by natural phenomena such as sea anemones and the human esophagus, all of which can expand in response to internal pressure—and by the work of team member David Gracias, a Johns Hopkins professor of chemical and biomolecular engineering who uses the principles of origami to build self-folding nanoscale devices—Kang used computer modeling to design a tube whose walls contain origami-like folds. When blood flow causes the pressure inside the tube to increase, the folds, which lend the device the creased appearance of a car air filter, allow it to expand by as much as 24 percent.

The researchers printed the tube using stretchy and durable biomedical-grade polymers. They then tested it using an experimental setup that mimics the pulsating nature of blood flow, and the increasing flow rate and pressure that accompany a growing body. By simulating the blood pressure patterns associated with different ages, the team showed that the shape-changing tube greatly reduced the amount of pressure that would otherwise accumulate and potentially cause a conventional conduit to fail.

One and done

Kang is testing various coatings on the conduit to prevent problems such as blood clots from interfering with the tube’s ability to expand. And he will soon implant the device in a pig to see how it performs in a living creature.

Within the next 10 years, Kang hopes, doctors will be able to scan the heart of a baby with a congenital defect, use design software to craft a custom-tailored conduit, manufacture it on-site with an inexpensive 3D printer, and install it in the ailing infant. The device would gradually expand over time, making it the last such operation the tiny but rapidly growing patient will ever need.

By Alexander Gelfand

This article originally appeared in the Summer 2019 Johns Hopkins Magazine >>

Welcome 2019 Research and Engineering Apprenticeship Program (REAP) Interns

We are pleased to welcome the following 2019 Research and Engineering Apprenticeship Program (REAP) Interns to the HEMI for the summer: Nia Lowery (From the Heart Christian School), Michelle Shen (Wootton HS), Angela Torrejon (Connelly School of the Holy Child), and Buena Zajmi (Quince Orchard HS).

HEMI’s REAP interns were selected through a very competitive application process.  Each student will work with a HEMI faculty advisor and have a graduate student/postdoctoral fellow as a mentor. The REAP mentors are: Paulette Clancy (Department of Chemical and Biomedical Engineering), Claire Hur (Department of Mechanical Engineering), Adam Phelan (Department of Chemistry), and Susanna Thon (Department of Electrical and Computer Engineering). We are looking forward to seeing the progress of these summer research projects.

REAP is an Army Educational Outreach Program that places talented high school students in research internships area colleges and universities. In REAP, a summer STEM program, students work on a hands-on research project under the direct supervision of a mentor, exposing them to the real world of research and allowing them to gain valuable mentorship and learn about education and career opportunities in STEM.  Each year, over 120 students participate in REAP nationwide at 42 participating universities.  Approximately 90% of the REAP interns pursue STEM studies at the post-secondary level.

From left: Angela Torrejon, Michelle Shen, Buena Zajmi, Nia Lowery.

HEMI Director K.T. Ramesh to Receive Warner T. Koiter Medal from ASME

Congratulations to HEMI founding director K.T. Ramesh, who has been selected to receive the 2019 Warner T. Koiter Medal from the American Society of Mechanical Engineers (ASME)! Ramesh is the the Alonzo G. Decker, Jr. Professor of Science and Engineering in the Department of Mechanical Engineering and holds joint appointments in the Department of Earth & Planetary Sciences and the Department of Materials Science & Engineering.

Ramesh was selected for “pioneering scientific contributions and international leadership in the area of dynamic material instabilities and material failure, with applications ranging from the mechanics of traumatic brain injury to nanostructured materials and planetary impact.”

Established in 1996, the Koiter Medal is given annually in recognition of outstanding and distinguished contributions to the field of solid mechanics, with an emphasis on the effective blending of both theoretical and applied elements of the discipline, and on a high degree of leadership in the international solid mechanics community.

The formal presentation of the award will take place during the 2019 ASME Mechanical Engineering Congress & Exposition this November.

Three HEMI Fellows Receive 2019 Johns Hopkins Discovery Awards

Congratulations to HEMI Fellows Anthony Shoji HallClaire Hur, and Sung Hoon Kang, whose faculty teams each received a 2019 Johns Hopkins Discovery Award! Professor Hall is an assistant professor in the Department of Materials Science & Engineering, and Professors Hur and Kang are assistant professors in the Department of Mechanical Engineering.

The Johns Hopkins Discovery Awards program provides grant awards to cross-divisional teams, comprised of members from at least two schools or affiliates of the university, who are poised to arrive at important discoveries or creative works. Hall’s team (made of professors from the Whiting School of Engineering and the Krieger School of Arts & Sciences) will study the “Design of Interfaces between Porous and Non-Porous Materials for Energy Applications.” Hur’s team (consisting of a professor in the Whiting School and another in the School of Medicine) will investigate “Injectable Hydrogel Protected Islet Cells for Long-term Glycemic Control in Diabetes.” The topic of Kang’s team (a collaboration between professors in the Whiting School and the Krieger School of Arts & Sciences) is “Decoding the Biomechanics and Physics of Cetacean Biosonar.” Click here for the full list of awardees and their projects.

The program is meant to encourage collaboration across academic disciplines and divisions under the belief that the most challenging questions cannot be answered entirely by one discipline alone. These awards are expected to spark new, synergistic interactions between investigators across the institution and lead to work of the highest quality and impact. Recipients of the award are celebrated at an event each fall.

Congratulations again to our HEMI awardees!

Three HEMI Fellows Receive Johns Hopkins Catalyst Awards

Congratulations to HEMI Fellows Anthony Shoji Hall, Michael Shields, and Daniel Viete who have been selected as three of 33 early-career faculty members to receive a 2019 Johns Hopkins Catalyst Award. Professors Hall, Shields, and Viete are assistant professors in the Department of Materials Sciences & Engineering, the Department of Civil Engineering, and the Department of Earth & Planetary Sciences, respectively.

The Catalyst Award program offers winners the means and opportunities to pursue a wide range of projects, from disease treatments to environmental studies. Recipients of Catalyst Awards are selected based on their accomplishments to date, creativity and originality, and academic impact. Each awardee will receive a $75,000 grant to support their work over the next year, as well as the opportunity to participate in mentoring sessions and other events. Click here to view the other 2019 awardees.

The program is open to any full-time faculty member appointed to a tenure-track position at least three and no more than 10 years ago. This year, more than 90 senior faculty members from across the university served on the committee that selected the awardees from a pool of 115 submissions. Recipients are celebrated at an event each fall.

Congratulations again to our HEMI awardees!

Christopher Sloan Joins HEMI as 2019 HEMI/MICA Extreme Arts Program Artist-in-Residence

We are excited to announce that Prof. Christopher Sloan will be joining HEMI as our 2019 HEMI/MICA Extreme Arts Program Artist-in-Residence. Sloan has years of experience producing works that translate complex science to immediately intelligible and visually striking works of visual art. He currently teaches both at MICA and at the Academy of Art, University of San Francisco.

As part of his residency, he plans to visualize areas invisible to the human eye, specifically those on very small scales, such as that of atoms, molecules and nano-scale structures. Using 3D models to visually represent these invisible spaces, Sloan plans to cast these models in rhodium plated brass to create physical manifestations of these invisible worlds.

The HEMI/MICA Extreme Arts Program is an initiative that brings faculty and students from both institutions together to explore unique perspectives on extreme events.  The program aims to encourage collaboration among artists and researchers to examine data, interpret outcomes, and translate results from extreme events in new ways. It is our hope that this dialogue will create a stronger community through a shared sense of curiosity and exploration.

If you would like to learn more about the program, please follow the link below: https://hemi.jhu.edu/academic-programs/hemimica-extreme-arts-program/.

Dr. Morgana Trexler of the Johns Hopkins Applied Physics Lab Joins HEMI

Please join us in welcoming the newest HEMI Fellow, Morgana Trexler! Dr. Trexler is a Materials Engineer with the Johns Hopkins Applied Physics Laboratory whose interests include high rate impact mechanics, armor, biomechanics, multifunctional and expeditionary materials. She received her doctorate in Materials Science and Engineering at the Georgia Institute of Technology. In 2014, she won the Outstanding Young Engineer award from the Maryland Academy of Sciences.

Welcome to HEMI, Dr. Trexler!


HEMI PhD Candidate Suhas Prameela Accepts MEDE-MSA Fellowship

Congratulations to Suhas Eswarappa Prameela on receiving the MEDE-MSA Research Fellowship! This fellowship enables current graduate students or postdocs working within the MEDE program the opportunity to participate in research activities at a MSA-affiliated university in the United Kingdom. With this fellowship, Prameela plans to explore the microstructure evolution of binary Magnesium alloys during thermo-mechanical processing. Prameela is a PhD candidate working in the Metals CMRG with Prof. Timothy Weihs. During the fellowship period, Prameela will work with Prof. Joseph Robson in the Department of Materials Engineering at the University of Manchester.

The MEDE-MSA fellowship is only open to graduate students or postdocs funded on MEDE whose principal faculty advisor is a current MEDE principal investigator (PI). The fellowship provides $6,000 (US) to support travel, housing and incidental costs. It is expected that the fellowship will be approximately eight weeks in duration which can be conducted throughout the year.

HEMI Fellow Muyinatu Bell to Receive Maryland Outstanding Young Engineer Award

HEMI Fellow Muyinatu Bell, an assistant professor in the Department of Electrical and Computer Engineering and the Department of Biomedical Engineering, has been chosen by the Maryland Academy of Sciences to receive the Maryland Outstanding Young Engineer Award.

Conferred by the Maryland Science Center, this award recognizes and encourages the important work being done by Maryland’s young professional engineers.
 As director of the Photoacoustic and Ultrasonic Systems Engineering (PULSE) Laboratory, Bell and her team integrate optics, acoustics, robotics, electronics, and mechanics, as well as signal processing and medical device design, to engineer and deploy innovative biomedical imaging systems that not only address unmet clinical needs, but also significantly improve patient care.

Congratulations, Prof. Bell!