Over recent years, technological developments in robotics have led to novel and less invasive techniques for surgery. In this framework, open surgery is often replaced by less invasive techniques, such as laparoscopy, towards Minimally Invasive Surgery (MIS). MIS has brought substantial benefits to the patient, such as: (1) less traumatization, (2) less risk of infection, (3) shorter recovery time and (4) a better cosmetics. In laparoscopic surgery, a single large incision is replaced by multiple small incisions (from 1 to 15 mm in diameter) through which physicians introduce long instruments for performing the medical procedure . Due to advantage in reducing the surgical trauma, postoperative pain and cosmetic problems, the laparoscopic approach has been adopted in several medical fields, such as urological, thoracic and pediatric surgery.
Although much work has been done to develop dexterous, multi-degree of freedom forceps and grippers, they are still inadequate to grasp, manipulate or push aside internal organs. Force feedback or touch sensation is limited in the currently available MIS tools, thus creating in most cases the potential for excessive force application during surgery and unintended tissue injury [3, 19, 26]. The risk of complications due to traumatization of soft tissues while trying to securely grip them is still an unresolved issue using conventional instruments, often characterized by sharp edges and no compliant properties.
Current research is focused on improvement of traditional tools, adding compliant constructive strategies or implementing force-feedback controlled forceps, to limit the force exerted and preventing damages on the tissues [9, 18, 21, 27]. Alternatively, a smart-designed instrument made up of intrinsically compliant materials would avoid the use of complex force-feedback control or at least would automatically avoid possible damages by limiting the maximum applicable force.
In addition to the robotic surgery field, there exist different previous inspiring examples on the use of soft grippers. Here some of them have been reported without the aim of being exhaustive. In 1991 Suzumori et al.  already developed a device based on pneumatic actuators which is able to manipulate relatively small objects. More recently, an entire hand with high dexterity and capabilities which resemble the functionality of a human hand has been developed by Deimel and Brock . In this case, the power source is fluidic, which guarantees compliance and relatively high interaction forces. Using the same principles, a soft gripper inspired by the star fish has been developed by Ilievski et al. , where the fluidic source is used to close the “fingers” around the objects. The main limit on using this actuation technology is represented by the low capability of miniaturization without a dramatic decrease of mechanical performance. Electro Active Polymers (EAP) are also a viable way of approaching miniaturization, but ionic EAP actuation velocity does not meet the usual timescale needed for surgical operations (Ionic Polimer Metal Composite based fingers in ); on the other hand, the high electric fields necessary for the electric EAP (the Dielectric Elastomer Minimum Energy Structure in ) do not allow a straightforward use of these technologies. A comparison between the reviewed existing soft robotic grippers and the system proposed in this work is presented in Table 1. Shape Memory Alloys (SMA), with their outstanding downscaling properties and high power density, could be a good alternative, but the high temperature and current necessary for their activation still represent an unsolved issue for their use in the surgical field. Only a few number of pioneering works exist for soft instruments applied in surgery [6, 13, 24], but no one has still ventured into the design of a totally soft gripping tool for surgery. The application of soft robotics in surgery still represents a challenge, especially for precision tasks, because of the lack of reliable modelling and control algorithms .
This study proposes a method to exploit specific soft robotics technologies in the surgical field. The idea at the base of this proposal is to study the feasibility of grasping soft tissues by using a soft instrument based on under-actuated mechanisms. The advantages are all related to the intrinsic compliant properties of the elastomeric material chosen to fabricate the tool, which would allow getting safely closer to soft tissues inside the unstructured workspace of the abdominal cavity, without the risk of damaging blood vessels or delicate organs during the manipulating procedures.