Abstract: Known time reversal methods consist of three steps which may be listed as (i) the recording of signals and (ii) the time reversing of the recorded signals, and (iii) the transmission of the time-reversed signals. The first and third steps of the above process are retained, but the second step is modified. The empirical signal is transformed to fit mathematical forms taught by the mathematics of singularity and catastrophe theory that ensure a structural stability to the waveforms that will be received, when the time reversed signals are transmitted again. This structural stability ensures robustness of the waveform and the predominant direction of the flux of energy of the waveform, and improves controllability of the location of the high magnitude regions of the energy flux despite limited knowledge of the exact properties of the medium. Applications to drug delivery in the brain, and geophysical applications are envisaged.

Abstract: Acoustic waves exhibit force that pushes objects along the direction of sound propagation. Precise motions require well-focused beams. The technique of time-reversal acoustics (TRA) overcomes beam distortions introduced by propagation along irregular paths to focus sound without knowledge of the medium properties. TRA requires a small receiver to be placed at a point of desired focus. The invention disclosed refines TRA by introducing data matching schemes to extend the points of focus beyond the location points of the receivers. With as few as two receivers, a large region can be manipulated with well-focused acoustic beams and with no receiver at a desired point of focus. Applications are described in drug delivery in medicine; environmental fluid contaminant control; and in oil exploration, for retrieving oil stuck in underground pockets.

Abstract: A medical device for delivering material through tissue into a defined area of a patient may comprise: a material delivery element through which the material may flow out of a delivery end; the delivery end having an opening that can be inserted through a surface of the tissue; and a sealing system proximal to the delivery end that can extend away from the material delivery element along the surface of the tissue and apply pressure to the tissue after the material delivery element has been inserted through the surface of the tissue. A physical barrier may be provided on the material delivery device to reduce back flow loss of delivered material.