WINDLASS

Capillary windlass: exploiting spider thread properties to engineer bioinspired micron-sized motors, actuators, sensors or flexible electronic components

Market Challenges
Biological materials form a great source of inspiration for the design of new types of materials and structures. Spider's capture silk is a material exhibiting exceptional mechanical properties, in particular super-extensibility, adaptable rigidity, and surprising ability to relax and then quickly to re-tauten under compression to adapt itself to outside conditions. It receives from the spider very powerful biological aqueous glue droplets that are able to fold and to roll up the thread within themselves.
There is a growing demand for material innovation regarding the need for more powerful electronic components, for lightened structures in transport industry, for safety with more resistant materials, etc. Development of fibers inspired by spider silk could therefore be a solution.

Innovative solution
Biological materials form a great source of inspiration for the design of new types of materials and structures. Spider's capture silk is a material exhibiting exceptional mechanical properties, in particular super-extensibility, adaptable rigidity, and surprising ability to relax and then quickly to re-tauten under compression to adapt itself to outside conditions. It receives from the spider very powerful biological aqueous glue droplets that are able to fold and to roll up the thread within themselves.
There is a growing demand for material innovation regarding the need for more powerful electronic components, for lightened structures in transport industry, for safety with more resistant materials, etc. Development of fibers inspired by spider silk could therefore be a solution.

Development status
The proof of concept is done. It is based on the deposit of an oil droplet on a polyurethane micro-thread. The thread folds and rolls up within the droplets by capillary compression (figure 1b). The reserve of thread in droplets allows a significant extensibility.
- Extensibility: can reach 100 times its initial length
- No bending : the thread remains straight and adapts itself under compression

These results were validated on various materials:
- Thermoplastic PolyUrethane (TPU) with silicone oil
- Thermoplastic PolyUrethane (TPU) with ethanol
- Thermoplastic PolyUrethane (TPU) with a glycerin / ethanol mixture
- PolyLactic Acid (PLA) with silicone oil
- PolyCaproLactone (PCL) with silicone oil
- Glass nano-fiber with silicone oil