Catheter-based cardiac ablation is the preferred method of treating atrial fibrillation. Conventionally, the catheter is navigated in the heart using X-ray fluoroscopy imaging and an electroanatomical map. Although successful, these imaging modalities do not provide real-time feedback on the quality of lesions created, which in turn could lead to recurrence of arrhythmia. Intracardiac echo (ICE) catheter provides real-time imaging within the heart to visualize both the ablation catheter and lesions created. However, manipulating the ablation and ICE catheters simultaneously is tedious and time consuming. As a first step towards developing a robotic ICE catheter that can autonomously follow the ablation catheter and monitor the lesions, we have developed a dynamic model for the ICE catheter. The model is based on the Cosserat theory for flexible rods that relies on strain parametrization. The model also accounts for frictional forces between the catheter sheath and tendons, external loads and fluid forces acting on the catheter. A good nominal model for describing the catheter dynamics is essential to develop a robust control scheme for the robotic ICE catheter. The parameters of the ICE catheter are estimated using weight release, tendon-driven actuation and fluid flow experiments. To the best of our knowledge, this is the first dynamic model for the ICE catheter that accurately reflects the dynamics of the catheter under pulsatile fluid flow within a heart phantom.

Untethered mobile microgrippers exhibit flexibility and agility in small and constrained environments as precise and accurate robotic end-effectors, with promising potential applications in cell manipulation and microassembly. Here, we propose the first scheme to independently and simultaneously position two microgrippers on a horizontal plane for parallel targeted cargo delivery using a single global input. The separation and orientation of the two-microgripper pair are modulated by the local magnetic interactions between the two microgrippers, which are governed by a global magnetic field. The microgripper action of grasping or releasing cargoes is fully controlled by the global magnetic field without requiring additional thermal, chemical, or other stimuli. Thus, the proposed strategy only requires a single input, i.e., a global magnetic field, to control two microgrippers and therefore is simple to implement and fast-acting. As a demonstration, two microgrippers are maneuvered by a global magnetic field to pick up two cargoes and deliver them to their respective destinations. The parallel operation of two microgrippers can potentially double the overall throughput and enable the tasks that require team cooperations. The two 3D microgrippers configuration is intuitive in teleoperations, since it imitates the two-hand case of human beings.