Wet adhesion for a miniature mobile intra-abdominal device based on biomimetic principles

An assessment of adhesion between the peritoneum and various micro/ nanopatterned polymer surfaces is presented as a key step in the design of a miniature intra-abdominal device for use in minimally invasive surgery practices. Of particular interest is the gathering of necessary information concerning understanding and quantifying the forces required to enable such a device to adhere to, move over, or detach and reattach to surface tissue without any damage to the latter. A micro-tribometer apparatus is used for this purpose, and results show that the adhesion force generated between the polymer and peritoneum does not scale linearly with nominal contact area. It is found that a non-optimized polymer surface patterned with a homogeneous micro-pillar structure, having an area of 113 mm2, when in contact with the peritoneum, is able to generate an adhesive force of 70 mN; six to eight such pads would in principle be capable of supporting a device/payload weighing 40–50 g. A discussion is provided of the mechanism(s) by which the adhesion is achieved and how the findings may impact on the eventual design and subsequent manufacture of a working intracorporeal device.

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Grasping Contact Analysis of Viscoelastic Materials With Applications in Minimally Invasive Surgery

Advances in Bioengineering, Biomedical and Safety Systems ◽

10.1115/imece2006-13081 ◽

2006 ◽

Cited By ~ 2

Author(s):

Ali Bonakdar ◽

Javad Dargahi ◽

Rama Bhat

Keyword(s):

Minimally Invasive Surgery ◽

Minimally Invasive ◽

Closed Form ◽

Contact Force ◽

Invasive Surgery ◽

Contact Area ◽

Biological Tissues ◽

Closed Form Expression ◽

Viscoelastic Materials ◽

Form Analysis

This paper presents a method to determine the contact force and pressure on the surface of viscoelastic objects grasped by an endoscopic grasper, used in Minimally Invasive Surgery (MIS). Normally, an endoscopic grasper is corrugated (teeth-like) in order to grasp slippery tissues. It is highly important to avoid damage to the tissues during grasping and manipulation in endoscopic surgery. Therefore, it is essential to determine the exact contact force on the surface of the tissue. To this end, initially a comprehensive closed form analysis of grasping contact force and pressure on elastic and particularly viscoelastic materials which have similar behavior as that of biological tissues is studied. The behavior of a rigid grasper with wedge-like teeth, when pressed into a delayed elasticity material is being examined. Initially, a single wedge penetrating into a solid is studied and then is extended to the grasper. The elastic wedge indentation is the basis of this study and the effects of time are included in the equations by considering the corresponding integral operator from viscoelastic stress-stain relations. Under the action of a constant normal load, the penetration of the indenter and the contact area will change. In this research, the variation of the contact area with time and the grasping contact force is studied. The results of this study which provides a closed form expression for grasping contact force and contact area are compared with those from elastic analysis.

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