Expanding medium compatibility with lateral-field optoelectronic tweezers

A circuit model and impedance analysis of lateral field optoelectronic tweezers (LOETs) are presented. The circuit elements are derived in terms of the geometrical and material properties of the system. Results from the model show that LOETs can function in electrically insulating suspension media. This is in contrast to conventional vertical-field optoelectronic tweezers (VOETs). The impedance mismatch effects that cause issues for VOETs are shown to be absent in LOETs as the medium impedance appears as an element parallel to the photoconductor impedance instead of being in series. Results from the model are found to be in good agreement with electric field results obtained from full-wave numerical solvers. Demonstrating that LOETs do not suffer from the same impedance constraints as VOETs enables a broader range of suspension media and applications to be explored.