A bio-inspired expandable soft suction gripper for minimal invasive surgery-an explorative design study.

Gripping slippery and flexible tissues during minimal invasive surgery (MIS) is often challenging using a conventional tissue gripper. A force grip has to compensate for the low friction coefficient between the gripper's jaws and the tissue surface. This study focuses on the development of a suction gripper. This device applies a pressure difference to grip the target tissue without the need to enclose it. Inspiration is taken from biological suction discs, as these are able to attach to a wide variety of substrates, varying from soft and slimy surfaces to rigid and rough rocks. Our bio-inspired suction gripper is divided into two main parts: (1) the suction chamber inside the handle where vacuum pressure is generated, and (2) the suction tip that attaches to the target tissue. The suction gripper fits through a∅10 mm trocar and unfolds in a larger suction surface when being extracted. The suction tip is structured in a layered manner. The tip integrates five functions in separate layers to allow for safe and effective tissue handling: (1) foldability, (2) air-tightness, (3) slideability, (4) friction magnification and (5) seal generation. The contact surface of the tip creates an air-tight seal with the tissue and enhances frictional support. The suction tip's shape grip allows for the gripping of small tissue pieces and enhances its resistance against shear forces. The experiments illustrated that our suction gripper outperforms man-made suction discs, as well as currently described suction grippers in literature in terms of attachment force (5.95±0.52 N on muscle tissue) and substrate versatility. Our bio-inspired suction gripper offers the opportunity for a safer alternative to the conventional tissue gripper in MIS.

Recurrent Braiding of Thin McKibben Muscles to Overcome Their Limitation of Contraction.

This study presents a novel idea of rebraiding thin McKibben muscles to overcome their limitation of contraction. The thin McKibben muscles, presented in the authors' previous work, have the flexibility that allows them to be braided. According to the experimental results of our previous research, the original single muscles have a contracting ratio of 28%, and the corresponding value for the muscles braided once is 37%. In this research, we achieved 41% contraction of thin McKibben muscles by braiding twice. The contraction ratio increases if the muscles are braided more. They will then overcome their limitation of contraction. In this report, several prototypes of muscles with different braiding times are designed, fabricated, modeled, and tested. As a result, the increase in the contraction ratio was confirmed from both a theoretical and an experimental point of view; the results were promising. We believe that recurrent-braided thin McKibben muscles will considerably help improve and develop various soft robotic applications in cases where a high contraction ratio is required.

Active Textile Braided in Three Strands with Thin McKibben Muscle.

This article presents an active textile braided in three strands with thin McKibben muscle. The fabrication of a textile using thin McKibben muscle as thread can be accomplished using a unique braiding method, developed in this study, to provide an active textile that shrinks along the transverse surface direction. This textile-type actuator is suitable as a type of soft robotic actuator for application in wearable robots and musculoskeletal robots because it is extremely lightweight, flexible, and easily applied to robot structures. In this article, the design and characteristics of a braided muscle in three strands, acting as the basic component of an active textile, as well as the design and static characteristics of the active textile, are presented. In addition, theoretical models are proposed for the active textile, and their theoretical characteristics are accordingly derived. The static characteristics of active textiles woven using various design parameters were then evaluated through experiments and modeling. The active textiles were found, both theoretically and experimentally, to provide a greater contraction ratio than a single muscle strand.

Study on a practical robotic follower to support home oxygen therapy patients--questionnaire-based concept evaluation by the patients-.

Home oxygen therapy (HOT) is a medical treatment for the patients suffering from severe lung diseases. Although walking outdoors is recommended for the patients to maintain physical strength, the patients always have to carry a portable oxygen supplier which is not sufficiently light weight for this purpose. Our ultimate goal is to develop a mobile robot to carry an oxygen tank and follow a patient in an urban outdoor environment. We have proposed a mobile robot with a tether interface to detect the relative position of the foregoing patient. In this paper, we report the questionnaire-based evaluation about the two developed prototypes by the HOT patients. We conduct maneuvering experiments, and then obtained questionnaire-based evaluations from the 20 patients. The results show that the basic following performance is sufficient and the pulling force of the tether is sufficiently small for the patients. Moreover, the patients prefer the small-sized prototype for compactness and light weight to the middle-sized prototype which can carry larger payload. We also obtained detailed requests to improve the robots. Finally the results show the general concept of the robot is favorably received by the patients.