Light patterned electrical fields have been widely used for the manipulation of microparticles,
from cells to microscopic electronic components. In this work, we explore a novel
electromechanical phenomenon for particle focusing and sorting where the electrical field
patterns are shaped by a combination of the light patterned photoconductor and the channel
geometry. This effect results from the combination of particle polarisation described by
the Clausius–Mossotti relation and the engineering of large electric gradients produced by
choosing the channels height to suit the size of the particles being manipulated. The matched
geometry increases the distortion of the field created by a combination of the illuminated
photoconductor and the particles themselves and hence the non-uniformity of the field they
experience. We demonstrate a new channel integration strategy which allows the creation of
precisely defined channel structures in the OET device. By defining channels in photoresist
sandwiched between upper and lower ITO coated glass substrates we produce robust channels
of well controlled height tailored to the particle. Uniquely, the top substrate is attached before
photolithographically defining the channels. We demonstrate versatile control using this effect
with dynamically reconfigurable light patterns allowing the retention against flow, focusing
and sorting of micro particles within the channels. Contrary to traditional designs, this channel
integrated device allows patterned micro channels to be used in conjunction with conductive
top and bottom electrodes producing optimal conditions for the dielectrophoretic manipulation
as demonstrated by the rapid flow (up to 5mm s−1
) in which the particles can be focuse
