This first soft hand consists of thin foil layers, which have been joined together to form more complex drives in a sandwich construction. Five fingers, built up from 6 foil layers each, functionally welded in pairs, with the middle two foils forming the skeletal structure filled with epoxy resin. The outer two foil layers each form a fluidic muscle. For this purpose, two thin films were welded together in such a manner that chambers were formed in a row and connected to each other. When this structure is inflated with a gas or liquid, it contracts by about 20 % of its length, similar to the natural muscle, and the finger curls up like a bow.

 

 After a practical semester and his diploma thesis at the Karlsruhe Research Center (now KIT), Stefan Schulz graduated with a degree in electrical engineering and device systems technology from the University of Rostock and took up a position as a research assistant at the Research Center. Already as a student at the University of Rostock, Schulz worked on the development of alternative miniature drives and patented a process for the production of planar fluid drives on a foil basis. At the Research Center, he continued developing this technology, particularly targeting applications in the field of fluidic robotics, so-called soft robotics in the environment of medical technology research topics. The aim of the work was to develop new drives for instruments used in minimally invasive surgery. Schulz's first applications for the new technology were flexible fluid actuators, miniature catheters for diagnostics, endoscope guidance systems for minimally invasive surgery and diagnostic colonoscopy systems. Fluidhand 1 was created as a “by-product” during the development of a camera guidance system for laparoscopy. The same artificial muscles that enable the movement of a laparoscope camera also work in the Fluidhand 1. In this process, two layers of film are welded together in a diamond-like pattern to form a chamber. When a pressure is applied to this chamber, the flexurally limp but stretch-resistant foil layers form circular arcs, resulting in a shortening of the previously flat structure. The artificial muscles formed in this way work as agonist and antagonist in the Fluidhand 1 and enable the artificial finger and thumb to be bent and stretched and stiffened. A single finger can describe a 180 degree arc, but the force of the artificial muscles is very low due to the material and not suitable for holding objects heavier than approx. 100 g.