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Current Directions in Biomedical Engineering

Joint Journal of the German Society for Biomedical Engineering in VDE and the Austrian and Swiss Societies for Biomedical Engineering

Editor-in-Chief: Dössel, Olaf

Editorial Board Member: Augat, Peter / Buzug, Thorsten M. / Haueisen, Jens / Jockenhoevel, Stefan / Knaup-Gregori, Petra / Kraft, Marc / Lenarz, Thomas / Leonhardt, Steffen / Malberg, Hagen / Penzel, Thomas / Plank, Gernot / Radermacher, Klaus M. / Schkommodau, Erik / Schmitz, Georg / Stieglitz, Thomas / Urban, Gerald A. / Witte, Herbert

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2364-5504
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Bionic forceps for the handling of sensitive tissue

Lucia Kölle
  • Corresponding author
  • University of Stuttgart and Fraunhofer Institute for Manufacturing Engineering and Automation IPA, Nobelstraße 12, 70569 Stuttgart, Germany
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/ Oliver Schwarz
Published Online: 2016-09-30 | DOI: https://doi.org/10.1515/cdbme-2016-0023

Abstract

Anatomical forceps are used for the handling of sensitive structures in medicine. Structures which are manipulated with these forceps can get damaged or slip out of the grip of the forceps. This paper presents a forceps using the bionic Fin-Ray-Effect inspired by fish-fins in order to handle vulnerable structures in particular. During the process of development, functional models of this forceps were designed, 3D-printed and evaluated.

Keywords: biomimetic; bionics; Fin-Ray-Effect; forceps; surgical instruments; tweezers

1 Motivation

To handle vulnerable structures such as blood vessels, nerves and soft tissue, anatomical forceps are used. Especially surgeons and anatomists use those standard instruments, which can damage tissue by exerting too much pressure on it. Another issue is that these forceps sometimes let tissue slip out of their grip.

2 Bionics

Bionics is the science of transferring concepts from nature into technological applications. Inspired by the results of biological evolution, innovations and improvements can be made which help solving current engineering problems. Commonly known examples for this are the Lotus-Effect, the Velcro fastener and adhesive foil inspired by geckos.

2.1 The Fin-Ray-Effect

The Fin-Ray-Effect is inspired by Fin-Rays of bony fishes. It describes that an isosceles triangle with elastic sides and stabilisers that are connected elastically (see Figure 1) does not bend away from a force that is applied to its side, but deforms in the way it is depicted in Figure 2 [1]. Thereby the tip of the triangle moves in the direction of the force that is applied. Fin-Rays adapt to the shape of objects that are pressed against their sides.

Fin-Ray.
Figure 1:

Fin-Ray.

Deformation of a Fin-Ray when a force is applied to its side.
Figure 2:

Deformation of a Fin-Ray when a force is applied to its side.

Functional model of the Fin-Ray-Forceps.
Figure 3:

Functional model of the Fin-Ray-Forceps.

3 Benefits of using the Fin-Ray-Effect in medical forceps

Because of the utilisation of the Fin-Ray-Effect, the jaw parts of the tweezers adapt to the shape of the object that is picked up or held with it. Thereby, the forces that are applied distribute over the larger contact area so that less pressure affects the object.

Furthermore, objects are less likely to slip out of the grip of a Fin-Ray-Forceps due to an effect that keeps an object that is held between two Fin-Rays in an equilibrium position. Even if it is externally moved out of the position, the system moves back in the equilibrium position [2]. The usual gripping and holding properties can be used when tissue is handled with the tip of the Fin-Ray-Forceps. Using this tip, relatively strong force can be applied to the object that is manipulated and deform it as usual forceps would.

4 Methods

After comprehesive literature research and a cost-benefit-analysis, it was decided to improve tweezers for the handling of sentitive tissue in medicine by the use of the Fin-Ray-Effect. Questionnaires were sent to surgeons and anatomists in Germany, Austria and Switzerland to gather data about their use and demands on anatomical forceps. This information was then used to choose the optimal combination of characteristics via morphological analysis of the possible attributes. Experiments were conducted to identify the optimal width-to-height ratio and number of stabilizers for two Fin-Rays that encompass cylinders between them and adapt to their shape as good as possible. Based on these features, models were designed using the computer-aided design software SolidWorks 2015 Premium (Dassault Systèmes SolidWorks Corp.) and then manufactured using 3D-printing (stereolithography and selective laser sintering). The CAD-models were improved, manufactured and evaluated iteratively until their performance was satisfying. The final models were then tested and presented to end-users to receive their feedback.

One of these models is depicted in the following figure. It was manufactured using selective laser sintering.

Forceps holding a segment of a plastic straw. The Fin-Ray-Forceps (left image) does not deform the straw noticeably, while the usual anatomical forceps compresses the straw considerably in order to secure the hold (image on the right).
Figure 4:

Forceps holding a segment of a plastic straw. The Fin-Ray-Forceps (left image) does not deform the straw noticeably, while the usual anatomical forceps compresses the straw considerably in order to secure the hold (image on the right).

Informed consent: Informed consent has been obtained from all individuals included in this study. Ethical approval: The conducted research is not related to either human or animal use.

5 Results

Fin-Ray-Forceps seem to be an appropriate and promising concept to manipulate vulnerable structures in medicine. They can be used to handle these structures without damaging them and could become an alternative to anatomical forceps or rather be used in addition to them if delicate tissue is handled.

The following figures show a segment of a plastic straw that is held with either a typical anatomical forceps or a Fin-Ray-Forceps. It can be seen that the bionic tweezers using the Fin-Ray-Effect adapt to the shape of the straw while the commercially available forceps clearly deforms the shape of the straw. The straw was chosen to represent an easily deformable hollow cylinder such as a blood vessel.

6 Prospects

Further testing of Fin-Ray-Forceps is required to examine that they are suitable for the intended application.

We are looking for a project partner with whom the necessary pre-commercial and commercial steps can be pursued.

Author’s Statement

Research funding: The author state no funding involved. Conflict of interest: Authors state no conflict of interest. Material and Methods: Informed consent: Informed consent is not applicable. Ethical approval: The conducted research is not related to either human or animal use.

References

  • [1]

    Festo Didactic. Accessory CD of “BionicsLab – Lernen von und mit der Natur”. Google Scholar

  • [2]

    Wegener K. Ein flexibles Greifsystem für Roboterassistenten im Haushalt. Heimsheim: Jost-Jetter. IPA-IAO-Forschung und Praxis; Nr. 456, 2007. p. 64–79. ISBN 3939890103. Google Scholar

About the article

Published Online: 2016-09-30

Published in Print: 2016-09-01


Citation Information: Current Directions in Biomedical Engineering, ISSN (Online) 2364-5504, DOI: https://doi.org/10.1515/cdbme-2016-0023.

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©2016 Lucia Kölle et al., licensee De Gruyter.. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. BY-NC-ND 4.0

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