Technology Offers

Shape-variable screw cap for ergonomic and effortless handling


A compact shap-variable screw cap with leverage effect created by the combination of elastic material and cleverly positioned crossed flexible structures facilitates the opening of containers and bottles. The screw cap was developed for people with limited strength in their hands, but also for screw caps that have to be twisted on very tightly by hand.


Caps are often very tightly screwed onto the container and require a profile to become “grippable”. As everyone knows, however, these systems do not work in every situation. If you don’t have any strength or have wet hands, such a cap quickly becomes a problem. Injuries cannot be ruled out in this case either.


As yet, ergonomic solutions which are easier to open, but are still able to close reliably, have not been able to establish themselves: Their design is often not compact enough, is too expensive to manufacture, or simply does not fulfill aesthetic requirements. Until now, an alternative has been to use additional aids which are placed over the original cap. However, this solution creates an additional expense and aids are not always available in every situation.


At the University of Stuttgart, a revolutionary screw cap principle has been developed with which a change in shape depending on the force of the hand can be realized over a small assembly space. A soft yet still positive-locking connection between hand and cap occurs: Greatly simplifying operation while utilizing the leverage effect and thus minimizing the effort required. The key to the technology is the combination of elastic material and cleverly positioned crossed, flexible structures. These are dimensionally stable when subjected to low forces. When applying somewhat stronger, more direct force however, a targeted change in shape is possible. Nevertheless, the structure remains stable enough to carry out the required transmission of force. The cap can be quickly and economically manufactured in any size using injection molding or additive production processes. Prototypes created during the invention process have already been able to prove their benefits in trials with test persons. The transmission of force was able to be increased by 50 to 100 per cent compared to conventional caps.

Sketch of the shape-variable grip principle: Pure traction with low hand force, additional leverage effect through force-dependent change of shape


  • Compact screw cap with leverage effect
  • Easier handling of operating elements
  • Ergonomic and effort-reducing using force-dependent geometry adjustment
  • Flexible and tailored in the smallest of assembly spaces
  • Aesthetic design



Fields of application

Man-machine interfaces are becoming more and more important in the age of robotics and increasing digitalization. However it is often the simple, everyday things in our lives for which there is not yet an optimum solution. Opening a water bottle with a screw cap, for example, is still a major challenge today for people with physical limitations in their hand functions because the majority of specially sealed caps require a large amount of contact pressure around the outside without offering much grip. Solutions are needed here which are simple and intuitive to use while being ergonomic at the same time.

Dr.-Ing. Hubert Siller
Technologie-Lizenz-Büro (TLB)
Ettlinger Straße 25
76137 Karlsruhe | Germany
Phone +49 721-79004-0
siller(at) |
Development Status
Prototyp / TRL5
Patent Situation
DE 102016117756 granted
Reference ID
Technologie-Lizenz-Büro GmbH has been entrusted with the exploitation of this technology and assists companies in obtaining licenses.