The use of a rotlin field in the dielectrophoretic separation of different types of bioparticle

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 behavior exhibits a two-dimensional variation in the xy plane, and moves in the x direction at a fixed velocity; at all times, the field is zero everywhere in the z direction. Because a rotating field is produced from the 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 behavior. 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 permittivity or conductivity or both 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.