Community Research and Development Information Service - CORDIS

Development of new electro-rheological fluid optimised for operation with sub-millimetre sized confinement

Electrorheological (ER) fluid is a smart material that changes its properties in the presence of an electric field. To date, the proliferation of ER fluid devices and applications has been restricted due to the difficulties associated with generating large enough electric fields to operate them effectively. Field strengths of the order of 1 MV/m (megavolt per metre) and greater are required producing discernible physical changes in the fluid. An electric field is generated between two electrodes at different potentials. The field strength is proportional to the potential difference between the two electrodes divided by the distance by which they are separated. For this project, it was necessary to produce electrical structures such that the fluid could be operated at voltages as low as 400V or less. Previous work with ER fluid had not demonstrated that this was practical, as it was usual to employ electrode separations ( gap ) of at least 1mm and to apply potential differences of the order 1kV (kilovolt) or more.

Therefore, as well as producing highly accurate structures to tight mechanical tolerances in order to produce electrode gaps of order 250 micrometres, the project required the development of a fluid that was suitable for use in such confined volumes. The class of ER fluids that was required for this application consists of solid particles dispersed in oil. These particles had sizes as large as 50-100 micrometres. This presented difficulties when used in confined spaces as their behaviour was unpredictable and inconsistent due to poor mobility of particles. It was hence necessary to develop a fluid that could be used when subjected to such confinement. The consortium therefore set about developing a means of preparing particles of order 10 to 20 micrometres for use in this environment. The new particles offered significant challenges with regards to reduced yield, difficulties associated with moisture loss and absorbtion and increased current consumption. All of these challenges were overcome to develop a new range of “low voltage” fluds that could be used in this environment that were still compatible with sealing materials, non-toxic and safe for disposal.

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Smart Technology Group Limited
U41, Coleshill Industrial Estate, Coleshill
B461JT Birmingham
United Kingdom
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