Selective separation of bioparticles by means of dielectrophoresis in a rotlin field

For the purpose of bringing about the separation of bioparticles by means of dielectrophoresis, a field is considered which at any given point is constant in magnitude, and rotating at a fixed angular velocity. The field pattern causing this behaviour exhibits a two-dimensional variation in the xy plane, and moves in the x direction at a fixed velocity; at any instant, the field is invariant in the z direction. Because a rotating field is produced from linear motion of the field pattern, it is termed a 'rotlin field'. The way in which a rotlin field may be produced is explained. It is evident that spatial harmonics will be present, and that these might affect bioparticle behaviour. A bioparticle in such a field will experience both rotational and dielectrophoretic effects. A change in the angular velocity of the rotating field set up at each point by the rotlin field, and a change in the electrical conductivity of the immersion medium, can cause some particles to exhibit negative, while others exhibit positive, dielectrophoresis. The resulting difference in their movement can be used to bring about their separation.