Electrorheological fluids undergo a phase change between Newtonian and thixotropic (Bingham
Plastic) with the application of an electric field having a field strngth in the killovolt/mm
A BMBF funded research project resulted in tactile displays using this principle. Several
degrees of tactor stiffness could be achieved for varying input voltages controlled optically by
means of a GaAs photosensor matrix.