ELASTOSIL® Film premiered at the K trade show three years ago. The launch generated remarkable and ongoing interest. Since the K debut, WACKER evaluated more than 450 inquiries from potential customers. In the meantime, several promising projects have materialized.
At this year’s K show, WACKER will present a selection of fascinating applications. The focus will be on wearable sensors, an application which leverages the electroactive properties of silicone rubber. The ultrathin film is embedded between two conductive electrodes made of silicones filled with carbon black. Together, the layers form a flexible capacitor that can store electric charge. If the silicone capacitor is stretched mechanically – for example due to movement – its capacitance also changes. Subtle nuances of such capacitance changes can be measured and thus used for sensory purposes in textiles, for example to capture and display body movements.
ELASTOSIL® Film is made without the use of solvents and manufactured under cleanroom conditions to eliminate any impurities. The patented production process yields continuous films which are extremely thin and homogenous. Film thicknesses down to 20 µm are available, with the thickness fluctuating less than five percent over the entire width. These and several other properties typical of silicone rubber enable technical applications which, up to now, were difficult to realize on an industrial scale.
Due to its dielectric properties, ELASTOSIL® Film – like all silicone rubbers – is an electroactive polymer. Silicone films are thereby able to respond to electrical stimulation under certain circumstances. If the upper and lower surfaces of the film are coated with a stretchable, electrically conductive material, the layers can be used like a capacitor. When a DC voltage is applied, the electrodes are attracted to each other electrostatically and compress the soft film material. The layer of elastomer material becomes thinner and spreads out in the plane. The capacitor becomes flatter and wider overall. When the capacitor is discharged, the elasticity of the film causes it to return to its original shape.
This property makes silicone films especially interesting for the following key electroactive technologies:
- Sensors: Sensors made of ELASTOSIL® Film enable the development of motion-capture clothing and sensor gloves, so-called wearables. They are increasingly in demand in sectors such as consumer electronics, healthcare, sports, rehab, leisure and wellness.
- Actuators: ELASTOSIL® Film creates new possibilities for manufacturers of actuators. In this case, electrical power is converted into mechanical movement, following the same electroactive principle. The entire process is silent and can be repeated as often as desired. This can be used to develop a wide array of novel products and technologies, such as pumps, switches, electrical relays, valves, artificial muscles, grippers or even loudspeakers.
- Generators: A pile of several hundred stacks of flexible capacitors consisting of dielectric silicone films can be used to transform movement into electrical power. Thus, silicone films enable novel power generators.
Silicone films can also add value to membrane technologies. They hold back water, but grant free passage to water vapor and certain gases. This gas permeability is highly selective: carbon dioxide, oxygen and water vapor pass through the silicone layer much faster than nitrogen. ELASTOSIL® Film could therefore serve as a membrane for removing a specific gas, such as carbon dioxide.