In order to improve understanding of an organ system, researchers often build physical/benchtop models that mimic the system sufficiently to reproduce, observe, and measure functions that are challenging to evaluate in the body. Though many such models of the cardiovascular and respiratory systems have been developed to simulate the motions of the beating heart and breathing, none faithfully replicates the mechanics of the diaphragm or faithfully mimics the three-dimensional twisting and compressive motion of the heart. Thus, the overall goal of this project is to build a lifelike, benchtop model that recreates the motion and function of the heart and the diaphragm using a combination of advanced robotic techniques and actual organic tissue. This model will provide insights into physiology, pathology and interdependence of the systems and serve as an innovative and effective teaching tool for educating students on cardiovascular and respiratory physiology and pathology. It will also serve as an anatomically and physiologically accurate testbed for implantable cardiac devices, representing a vast improvement over existing models and ultimately reducing the requirement for testing devices in animal models. Finally, it will act as an impactful visualization tool for educating and engaging the broader community (for example in museums and in Children's hospitals). The PI will use this demonstration and teaching model as one of many approaches in a multi-pronged initiative to recruit, train and retain a new generation of women in academic scientific positions.
The goal of this project is to shift the paradigm of benchtop simulators from one where the respiratory and cardiovascular systems are independently simulated with synthetic phantoms or ex vivo tissue and motion is passively driven by fluid or external components to one where functional dynamic tissue is recreated using programmable biomimetic soft active materials. Synthetic soft robotic muscular simulators for the diaphragm and heart muscle (myocardium) will be combined with ex vivo biological tissue (entire lungs and intracardiac structures respectively) to create "hybrid biorobots" that will enable accurate representation of lung and heart motion, while preserving key anatomical structures, thus maintaining form while recapitulating function. Clinically derived motion data of the diaphragm and heart will be used to develop algorithms to "program" the design of fiber reinforced biomimetic soft actuators. Subsequently, these active elements will be embedded in anthropomorphic matrices to mimic the form and function of the diaphragm and heart. Diaphragm-driven breathing mechanics and cardiovascular hemodynamics will be recreated using pressurized anatomical chambers and mock circulatory loops. The Research Plan is organized under three objectives. The FIRST OBJECTIVE is to create a modular, active biorobotic diaphragm that can be integrated into an in vitro testbed that can be used simulate physiological and pathological biomechanics and generate ex vivo lung ventilation. The in vitro testbed will integrate pressurized chambers separated by an interchangeable diaphragm mimic to replicate the physiologic pressures of the thoracic and abdominal cavities. Soft-robotic actuators will be programmed to mimic the desired diaphragm motion trajectory as computationally extracted from clinical MRI data. This will be the first functional soft robotic diaphragm mimic to replicate a variety of clinically derived diaphragm motions. The SECOND OBJECTIVE is to create a cardiovascular testbed including a biorobotic heart that recreates cardiac wall motion and generates pressure changes to simulate hemodynamic conditions. A novel hybrid fabrication process will be used to preserve the intracardiac structures (endothelial lining, septum, valves, papillary muscles and chordae tendinae) of the heart using ex vivo tissue (porcine hearts) or high-resolution 3D printing. The active heart muscle will be replaced with a synthetic soft material containing fiber-reinforced actuators oriented in desired configurations. The biorobotic heart will be integrated with a partially compliant vascular flow loop to simulate hemodynamics. This will be the first realization of a soft biorobotic heart that integrates organic intracardiac tissue with soft robotic myocardium and the first cardiac simulator where cardiovascular hemodynamics are driven completely by a myocardial substitute that is capable of replicating twist as well as compression, which is critically important in the performance assessment of medical implants. The THIRD OBJECTIVE is to integrate components to make a cardiorespiratory platform and to demonstrate its utility in a model to simulate respiratory and hemodynamic biomechanics of Fontan patients. Physical cavities of the respiratory simulator will be designed based on Fontan patients' CT and MRI data. Based on previous work, a controller that actuates physiological pressure profiles during a breathing cycle in a simulated chest cavity of a Fontan patient with total cavopulmonary bypass will be developed. The respiratory simulator will then be combined with a partially compliant vascular flow loop to simulate venous pressure and flow patterns of Fontan patients. This will be the first combined cardiorespiratory simulator using a soft robotic heart and diaphragm and the first platform to recreate the Fontan physiology including both trans-diaphragmatic pressures and abdominal pressure.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
