The present invention provides for a method of controlling mass movement of fluid material within a field of interest comprising using time reversal acoustic focusing. The time reversal acoustic focusing can be is used for simultaneous spatial and temporal focusing of acoustic energy to control the duration of localization and/or direction of movement of material within tissue or liquid within tissue. Both delivery of material and persistence with respect to target locations can be enhanced by focusing of sonic waveforms or transmissions towards targeted areas in a field of interest, such as within a patient.
STATEMENT OF GOVERNMENTAL SUPPORT
 The invention described and claimed herein was made in part utilizing funds supplied by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The government has certain rights in this invention.