A new manufacturing process for elastomers, which allows nanometer-thin silicone layers to fabricate artificial muscles, has been developed by researchers from Empa and the University of Basel. There are potential future medical applications since this type of artificial muscle is able to operate at a low voltage.
Electroactive polymers (EAP), also called elastomers, is used in a variety of applications ranging from operating camera lenses to powering windscreen wipers because it converts electrical energy into mechanical energy.
In a project entitled “SmartSphincter”, part of the Swiss Nano-Tera research programme, researchers from the University of Basel and Empa have now developed artificial muscles for treating incontinence. Micrometer-thick silicone layers need a several hundred volts in order to effectively operate. This is much too high for artificial muscles in the human body. However, nanometer-thin layers require only a few volts. Since the force exerted by these thin layers is very low, several thousand layers have to be put on top of each other in order to generate a sufficiently high force.
But, current manufacturing methods are not suited to the fabrication of such layered structures. The team headed by Bert Müller of the Biomaterials Science Center of the University of Basel, together with Florian Weiss and Gabor Kovacs from the Mechanical Systems Engineering department at Empa, developed a method of deposition which enables silicone layers to be fabricated that are much thinner than one micrometer. Additionally, the layers are extremely flat, with a surface roughness of less than one nanometer.
In the Empa lab, silicone molecules are vaporised with the aid of a high-voltage electrical current; this technique is known as electrospraying which is normally carried out using direct current. For the development of artificial muscles, however, the Empa scientists are experimenting with alternating current. Several thousands of layers created in this way can be built up to create artificial muscles which require an operating voltage of only 40 volts. This is roughly similar to the voltage of a button cell. The researchers hope that this technology can soon be used to produce an implant for treating incontinence.
This comparatively simple manufacturing process is highly suitable for industrial production and offers tremendous potential for the fabrication of artificial muscles which could be used, for example, to power windscreen wipers.
Source: Empa