Development of a Soft Robotics Diaphragm to Simulate Respiratory Motion

Liver cancer is the second leading cause of cancer deaths worldwide. Without treatment, the five-year survival rate is less than 5%. Liver tumors are often detected using MRI. MRI is preferable over other imaging modalities include absence of ionizing radiation, superior soft tissue contrast resolution, and multiplanar imaging capabilities. Needle interventions are then needed for further diagnosis (biopsy) and treatment (ablation). Respiratory motion is the main cause of inaxccurate needle placement leading to misdiagnosis and insufficient treatment. In order to train clinicians to compensate for the liver respiratory motion during intervention, and also test needle insertion robotics technologies, a realistic liver motion simulator is of great interest which can be used inside MRI scanner. In this study, an MR-compatible soft robotic platform is developed to simulate liver respiratory motion. Pneumatically actuated soft robotic actuators were developed and validated using finite element simulations. A feedforward controller was developed to control the input air pressures of the pneumatic actuators to simulate the respiratory motion. The evaluative experiments indicated that the developed soft robotics diaphragm could acceptably simulate liver respiratory motion in the two directions of motion: superior-inferior and anterior-posterior directions.