Omnidirectional Steerable Forceps With Flexible Joints and Skin-Like Stretchable Strain Sensors

Omnidirectional steerable forceps in keyhole procedures provide significant advantages in assisting medical practitioners with better motion coordination, improved dexterity, precision control, and reachability. However, most existing forceps lack the sense of interactive proprioception, imposing physical and cognitive challenges to the medical practitioners during manipulation. Herein, we report handheld steerable surgical forceps with two degrees-of-freedom equipped with skin-like soft stretchable strain sensors to determine the orientation and improve the perception. The performance of omnidirectional forceps integrated with sensory skin is characterized. Due to the reduced number of mechanical parts in the forceps by virtue of parallel continuum joints, the direct translation of motion from the proximal to the distal end is achieved. The distal parallel flexible joint enables a bending angle up to 40° and a bending radius of 7.5 mm. The hydrogel-based silver nanowire sensors mounted on the forceps like a stretchable skin show a maximum gauge factor of 11.8 under 80% strains. A mathematical model is developed to determine the tooltip orientation. The developed model validated with visual tracking shows 90-97% accuracy for angular displacements up to 30° in all directions. Assisting medical practitioners in a clinical environment is demonstrated in a cadaveric setting by providing proprioceptive information of the tooltip through OFISS.