学术报告：Mechanics and Geometry: From Twisted Embryonic Brain to Biohybrid Soft Robots
主讲人简介：Dr. Zi Chen is an Assistant Professor at Thayer School of Engineering at Dartmouth College. Dr. Chen received his bachelor’s and master’s degree in Materials Science and Engineering from Shanghai Jiaotong University, and a PhD in Mechanical and Aerospace Engineering from Princeton University. Before joining Dartmouth, Dr. Chen worked as a postdoctoral fellow in Department of Biomedical Engineering at Washington University in St. Louis. He was also a visiting scientist in the Weitz lab at Harvard University. Dr. Chen’s research interests cover such diverse topics as microstructural evolution in materials, phase transitions, mechanical instabilities of materials and structures, multistable structures, energy harvesting devices, stretchable electronics, biomimetic materials/devices, nanofabrication, mechanics of morphogenesis in biological systems, and cancer cell biomechanics. Dr. Chen's research has been supported by NIH, Society in Science, and American Academy of Mechanics. He has published over 60 peer reviewed journal papers and filed three US patents. Dr. Chen is also a recipient of the Society in Science - Branco Weiss fellowship and the American Academy of Mechanics Founder’s award.
Mechanical forces play a key role in the shaping of versatile morphologies, especially chiral and multistable structures, in both natural and synthetic systems.
In embryos, chiral structures can also arise via mechanics. The embryonic chick brain, for example, undergoes rightward torsion, one of the earliest organ-level left-right asymmetry events in development. Here we unveiled the mechanical origin of brain torsion and the associated development of left-right asymmetry, through both experiments and modeling.
Chiral structures can also be exploited in the design of energy harvesting devices. Long-term energy supply for electronic systems is challenging for implantable biomedical devices, like cardiac pacemakers. Energy harvesting can significantly extend the lifetime of these devices, however, no clinical translational technologies can efficiently convert the mechanical energy of the heart into electrical power without a thoracotomy and interfering with the cardiovascular functions. Here, we report a cardiac energy harvesting strategy, which is integrated into part of the existing pacemaker lead and otherwise with no direct contact of heart, by utilizing porous piezoelectric thin films in a bioinspired self-wrapping helical configuration for flexible integration with existing implantable medical devices. We demonstrate that this compact helical design can be seamlessly coupled with current leads without introducing additional implantation surgeries.This innovative cardiac energy harvesting strategy represents a significant step forward for clinical translation without a thoracotomy for patients, suggesting a paradigm for biomedical energy harvesting in vivo.
Many living organisms undergo conspicuous or abrupt changes in body structure, often accompanied by a behavioral change. Inspired by the natural metamorphosis, reconfigurable robotic systems can be designed to be multifunctional. Here we developed a tissue-engineered reconfigurable robot, which can be remotely controlled to adopt different mechanical structures for switching locomotive function. The actuation of the robot is by a muscular tail fin that emulates the swimming of whales and works as a cellular engine powered by the synchronized contraction of striated cardiac microtissue constructs. To achieve a transition of locomotive behavior, the robot can be optically triggered to transform from a spread to a retracted form, which effectively modifies the bending stiffness of the tail fins, thus minimizing the propulsion output from the “tail fin” and effectively switching off the engine. With the unprecedented controllability and responsiveness, the transformable robot is employed to work as a cargo carrier for programmed delivery of chemotherapeutic agents to selectively eradicate cancer cells. The realization of the transformable concept paves a promising pathway for potential development of intelligent biohybrid robotic systems.
The study of mechanics and geometry will facilitate understanding of morphology generation in natural and synthetic systems, and benefit the ongoing efforts in developing programmable micro-fabrication techniques and novel functional devices such as NEMS devices, active materials, drug delivery agents, energy harvesting devices, and bio-inspired robots. Studies of embryonic development can also benefit the future practices in preventing or treating certain diseases.