A method for acoustic control of particles

A method for acoustic control of particles in a space, the method including:

• providing particles in the space, wherein the particles are in an initial state which is a two-dimensional or three-dimensional state;
• selecting a desired state of the particles in the space to be achieved through control of the particles and which is a two-dimensional state or three-dimensional state;
• and,
• selectively creating different acoustic force fields to obtain the desired state of particles by changing the phase, frequency and/or amplitude of the acoustic waves and controlling the time each of the different acoustic force fields is applied for so that at least a portion of the particles move in a desired way in the space from the initial state to the desired state which involves performing the following steps:
• a) switching between selected different acoustic force fields to create a low force impulse control mode in which low force impulses are exerted on the particles and the acoustic force field exerted on the particles is effectively the sum of the selected different acoustic force fields so that the particles move to an intermediate state prior to another step being performed, or move to the desired state;
• and may include one or more of the steps:
• b) switching between selected different acoustic force fields to create a high force impulse control mode in which high force impulses are exerted on the particles so the particles reach the equilibrium point(s) of the acoustic force field that is present by the time the next acoustic force field is applied so that the particles move to an intermediate state prior to another step being performed, or move to the desired state;
• and
• c) switching between selected different acoustic force fields to create an intermediate force impulse control mode in which intermediate force impulses are exerted so that the particles move further towards the equilibrium point(s) of the acoustic force field that is present than in the low force impulse control mode without reaching them by the time next acoustic force field is applied so that the particles move to an intermediate state prior to another step being performed, or move to the desired state.

A method of calibrating an apparatus for performing a method for acoustic control of particles in a space, the apparatus including:

• acoustic wave generators for producing respective acoustic waves which combine to create the different acoustic force fields;
• and
• a control device for controlling the acoustic wave generators to create the different acoustic force fields, wherein the control device is operable to change the phase and/or amplitude of the acoustic waves produced by each of the acoustic wave generators in order to create the different acoustic force fields, and to control the time each of the different acoustic force fields is applied for;
• and
• wherein the control device is configured to control the acoustic wave generators to switch between the different acoustic force fields to exert force impulses on a particle, and
• wherein the method of calibrating the apparatus includes:
• d) selecting a pre-determined acoustic force field to be created to control movement of a particle in the space;
• e) applying the pre-determined acoustic force field to hold the particle in a desired position in the space;
• f) altering the pre-determined acoustic force field that is created to exert a force impulse for moving the particle along a path for a first set of acoustic wave generator time applied and maximum amplitude settings;
• g) observing movement of the particle to determine the type of force impulse that has been applied to the particle;
• h) using steps f) and g) to calibrate the control device in controlling the acoustic wave generators to obtain the desired force impulse to be applied on the particles to acoustically control the particles.