Cylindrical acoustic levitator/concentrator

A method for levitating particles in a fluid which comprises the steps of:

• (a) matching the breathing-mode acoustic resonance of a hollow, cylindrical piezoelectric transducer to the acoustic resonance of the interior thereof when filled with said fluid;
• (b) applying periodic electrical excitation to the surface of the cylindrical piezoelectric transducer such that resonant acoustic waves are generated in the interior of the cylindrical piezoelectric transducer;
• and
• (c) subjecting the particles to the equilibrium force pattern formed by the resonant acoustic waves such that the particles are suspended by the equilibrium force pattern.

An apparatus for concentrating particles suspended or entrained in a fluid which comprises in combination:

• (a) a cylindrical piezoelectric transducer having a hollow interior portion and wherein the breathing-mode acoustic resonance of said cylindrical piezoelectric transducer is matched to the acoustic resonance of the interior portion thereof when the interior portion is filled with said fluid;
• (b) a function generator for applying periodic electrical excitation to the surface of said cylindrical piezoelectric transducer such that resonant acoustic waves in are generated in the hollow interior portion of the cylindrical piezoelectric transducer;
• and
• (c) means for introducing the fluid having particles suspended or entrained therein into the region of the equilibrium force pattern formed by the resonant acoustic waves such that the particles move to the region of the equilibrium force pattern and are concentrated thereby.

An apparatus for levitating particles in a fluid which comprises in combination:

• (a) a cylindrical piezoelectric transducer having a hollow interior portion such that the breathing-mode acoustic resonance thereof is matched to the acoustic resonance of the hollow interior portion thereof when filled with said fluid;
• (b) a function generator for applying periodic electrical excitation to the surface of said cylindrical piezoelectric transducer whereby resonant acoustic waves are generated in the hollow interior portion of said cylindrical piezoelectric transducer;
• and
• (c) means for introducing the particles into the equilibrium force pattern formed by the resonant acoustic waves such that the particles are suspended by the equilibrium force pattern.

A method for concentrating particles suspended or entrained in a fluid which comprises the steps of:

• (a) matching the breathing-mode acoustic resonance of a hollow, cylindrical piezoelectric transducer to the acoustic resonance of the volume formed between the cylindrical piezoelectric transducer and a rigid cylinder surrounding the cylindrical piezoelectric transducer and coaxial thereto when the volume is filled with said fluid;
• (b) applying periodic electrical excitation to the surface of the cylindrical piezoelectric transducer such that resonant acoustic waves are generated in the volume between the cylindrical piezoelectric transducer and the rigid cylinder;
• and
• (c) subjecting the fluid having particles suspended or entrained therein to the equilibrium force pattern formed by the resonant acoustic waves such that the particles move to the region of the equilibrium force pattern and are concentrated thereby.

An apparatus for concentrating particles suspended or entrained in a fluid which comprises in combination:

• (a) a hollow, cylindrical piezoelectric transducer;
• (b) a rigid cylinder surrounding said cylindrical piezoelectric transducer and coaxial thereto, forming a volume therebetween such that the breathing-mode acoustic resonance of said cylindrical piezoelectric transducer is matched to the acoustic resonance of the volume when the volume is filled with said fluid;
• (c) a function generator for applying periodic electrical excitation to the surface of the cylindrical piezoelectric transducer such that resonant acoustic waves are generated. in the volume between the cylindrical piezoelectric transducer and the rigid cylinder;
• and
• (d) means for introducing the fluid having particles suspended or entrained therein into the region of the equilibrium force pattern formed by the resonant acoustic waves such that the particles move to the region of the equilibrium force pattern and are concentrated thereby.