A soft pop-up proprioceptive actuator for minimally invasive surgery

INTRODUCTION Surgical robots and miniaturized smart instruments have been developed to overcome limitations of current tools and further reduce invasiveness of surgical procedures [1][2]. This miniaturization effort, as well as the development of more flexible instruments that can navigate the body following complex anatomical paths toward the surgical target, often leads to the loss of sensory feedback and dexterity and increases design complexity. Developing mm-scale robots combining distal dexterity and sensor feedback at the surgical site would increase reliability and controllability, especially in flexible endoscopy, where the procedures are primarily based on visual feedback. However, this introduces several technical challenges because of the lack in viable manufacturing technologies at this scale: current approaches mainly rely on fiber optic based sensing systems [3]-[6]. Recently, a pop-up book inspired manufacturing technique has been utilized to fabricate surgical tools with embedded actuation and sensing [6]-[8]. Furthermore, soft materials and soft fluidic micro actuators have been introduced in this paradigm to fabricate soft pop-up mm-scale sensors and actuators for minimally invasive surgery (MIS) [8]. Advantages of this approach include low cost manufacturing, scalability, and flexibility in material selection. Furthermore, the use of soft material provides a safer interface with biological tissue. In this paper, we exploit the soft pop-up fabrication technique to develop a mm-scale bending actuator with proprioceptive capabilities based on capacitive sensing (Fig. 1).