Key points are not available for this paper at this time.
A stable force potential well was generated by two collimated focused ultrasonic (3.5 MHz) beams propagating along opposite directions. Latex particles (270-microns diameter) and clusters of frog eggs were trapped in the potential well. The trapped object can be moved axially or laterally by moving one of the PZT focusing transducers that generate the ultrasonic focused beams. The axial position of the trapped object can also be maneuvered by tuning the frequency of the electrical voltage applied on the transducers.
Junru Wu (1991) studied this question.