A Soft Robotic Phantom to Simulate the Dynamic Respiratory Motion of Human Liver

In percutaneous interventions for hepatic tumor treatment, organ motion caused by respiration can lead to inaccurate needle placement hence less effective therapeutic and diagnostic outcome. The aim of this study was to implement soft robotics technology to develop an actuated phantom that mimics respiratory motion in liver for needle insertion procedures. The actuated liver phantom should be MR-compatible as it will be used for testing needle insertion devices and prototypes in an MRI environment while considering the respiratory motion of the liver. The soft-actuated robotic phantom can also be used for training clinicians on MRI-guided percutaneous needle interventions such as manual biopsy and ablation. Pneumatic soft actuators were design and implemented in the phantom to achieve a smooth motion similar to liver respiratory motion. In order to evaluate the performance of the phantom, three common breathing types were simulated, as well as a normal and two abnormal breathing patterns in patients. Moreover, a normal respiration was simulated with different phantom weights to be representative for different liver masses. The results revealed that the developed robotic simulator is sensitive to feeding air pressure and actuating time period, and to a less extend to the phantom mass. Based on five cycle repetitions, the simulator could reproduce different respirations with a maximal deviation of 3mm in superior, 2mm in inferior and less than 1mm in anterior-posterior directions.