Abstract: An acoustofluidic device includes a substrate and an ultrasound transducer contacting the substrate. The substrate and the transducer combined have a set of acoustic natural system resonances determined by the material and the dimensions of the substrate and the transducer. Each system resonance has a resonance frequency and a resonance quality factor. A microfluidic cavity is provided in the substrate to contain a fluid, the cavity having a set of acoustic natural cavity resonances, each having a resonance frequency and a resonance quality factor, determined by the dimensions of the cavity and the speed of sound in a fluid to be contained in the cavity. The material and the dimensions of the substrate and the transducer are selected so that at least one individual cavity resonance has a resonance frequency corresponding to the frequency of a minimum in an impedance spectrum of the transducer.

Abstract: A method of performing an acoustofluidic operation, comprising the steps of: a. providing (1) an acoustofluidic device (10) comprising:—a substrate (12) in which a microfluidic cavity (30) is positioned, and—at least a first (50a) and a second (50b) ultrasound transducer (50), each provided in acoustic contact with the substrate (12) for transferring ultrasonic vibrations to the substrate and causing the substrate to vibrate, wherein the first and the second ultrasound transducers each comprise a first electrode (52) and a second electrode (56a, 56b) in contact with a piezoelectric or electrostrictive material (54), and wherein the first electrodes are in electric contact with each other, b. providing a fluid, such as a liquid (2) or liquid suspension in the microfluidic cavity (30), c.

Abstract: A method of performing acoustically enhanced sedimentation in a sample of a suspension comprising particles and a fluid is provided. The method comprises the steps of: i. introducing a volume of the sample into an accumulation zone of a microfluidic cavity; ii performing the substeps of: a. during a first time period: subjecting the volume to an acoustic standing wave configured to cause the particles in the volume to accumulate in at least a first region of the volume; b. during a second time period: subjecting the volume to a gravitational field affecting the particles and the fluid so that the particles accumulated in the at least one first region sediment in a first direction in relation to the direction of the gravitational field, thereby removing particles from the volume; and iii. moving the volume in a second direction opposite the first direction by introducing a subsequent volume of the sample into the accumulation zone of the microfluidic cavity. An acoustofluidic system is also provided.

Abstract: An acoustofluidic device comprising: a substrate in which a microfluidic cavity is positioned, and—a thin film ultrasound transducer provided in acoustic contact with at least a part of one surface of the substrate for transferring ultrasonic vibrations to the substrate and causing the whole substrate to vibrate, wherein the thin film ultrasound transducer preferably has a thickness of less than 100 ?m, such as less than 50 ?m, such as less than 5 ?m, such as less than 2 ?m, is provided. A method of performing an acoustofluidic operation and a method of manufacturing an acoustofluidic device are also provided.

Abstract: An acoustofluidic device is provided comprising a) a substrate, and b) an ultrasound transducer attached to, or in contact with, the substrate. The substrate and the ultrasound transducer combined have a first set of acoustic natural system resonances determined by the material and the dimensions of the substrate and ultrasound transducer. Each system resonance comprises a resonance frequency and a resonance quality factor. The device further comprises c) a microfluidic cavity provided in the substrate and containing a fluid, the cavity having a second set of acoustic natural cavity resonances, each having a resonance frequency and a resonance quality factor, determined by the dimensions of the cavity and the speed of sound in the fluid. The material and the dimensions of the substrate and ultrasound transducer are selected so that at least one individual cavity resonance has a resonance frequency corresponding to the frequency of a minimum in an impedance spectrum of the ultrasound transducer.

Abstract: A method of predicting one or more resonance frequencies for efficient operation of an acoustofluidic cavity in an acoustofluidic device is provided. The method comprises the steps of i. providing a first liquid filling the cavity, ii. obtaining a first impedance spectrum, by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies, iii. providing a second liquid filling the cavity, wherein the second liquid differs from the first liquid in its acoustophysical properties, iv. obtaining a second impedance spectrum, by measuring the electrical impedance of the ultrasound transducer as the ultrasound transducer is driven at the range of frequencies, and v.

Abstract: The invention relates to a method of performing an optical or electrical measurement in a sample of a disperse fluid, the sample comprising particles and a fluid. The method comprises the steps of: a) positioning the sample in a microfluidic cavity having a resonance frequency, b) subjecting the sample, in the cavity, to an acoustic standing wave configured for causing the particles to congregate in at least one first region of the cavity, thereby causing the fluid to occupy at least one second region of the cavity, wherein the frequency of the acoustic standing wave is varied between a frequency below the resonance frequency and a frequency above the resonance frequency, and c) performing an optical or electrical measurement in the fluid in at least one of the at least one second region of the cavity. Varying the frequency ensures reproducible results. The invention also relates to a system therefore and a method and system for measuring hematocrit.

Abstract: A method of performing a separation of a sample of a disperse fluid comprises the steps of: i. providing a sample of a disperse fluid comprising particles dispersed in a fluid, wherein the particles comprises at least a first type of particle and at least a second type of particles, wherein the absolute value of the acoustic contrast of the first type of particle, relative to the fluid, is lower than the absolute value of the acoustic contrast of the second type of particle relative to the fluid, and wherein the first and second type of particle either both have a positive acoustic contrast, or alternatively a negative acoustic contrast, relative to the fluid, ii. positioning the sample in a microfluidic cavity, iii.

Abstract: The invention relates to a method of performing an acoustophoretic operation, comprising the steps of: a. providing an acoustophoretic chip comprising a polymer substrate in which a microfluidic flow channel is positioned, b. providing at least one ultrasound transducer in acoustic contact with one surface of the substrate, c. actuating the at least one ultrasound transducer at a frequency f that corresponds to an acoustic resonance peak of the substrate including the microfluidic flow channel filled with a liquid suspension, and d. providing the liquid suspension in the flow channel to perform the acoustophoretic operation on the liquid suspension. The invention further relates to an acoustophoretic device, a method of producing an acoustophoretic device, and a microfluidic system comprising the acoustophoretic device.

Abstract: 1. A method of performing an acoustophoretic operation comprises the steps of: i. providing a fluid, ii. positioning the fluid in a microfluidic cavity, iii. subjecting at least one portion of the fluid, in the microfluidic cavity, to an acoustic wave, and iv. providing, in at least one first region of the at least one portion, a thermal inhomogeneity whereby the temperature of the fluid in the at least one first region differs from the temperature of the fluid in at least one second region of the remainder of the at least one portion. A microfluidic system is also disclosed.

Abstract: A method of predicting one or more resonance frequencies for efficient operation of an acoustofluidic cavity in an acoustofluidic device is provided. The method comprises the steps of i. providing a first liquid filling the cavity, ii. obtaining a first impedance spectrum, by measuring the electrical impedance of an ultrasound transducer connected to the acoustofluidic device as the transducer is driven at a range of frequencies, iii. providing a second liquid filling the cavity, wherein the second liquid differs from the first liquid in its acoustophysical properties, iv. obtaining a second impedance spectrum, by measuring the electrical impedance of the ultrasound transducer as the ultrasound transducer is driven at the range of frequencies, and v.

Abstract: The invention relates to a method of performing an acoustophoretic operation, comprising the steps of: a. providing an acoustophoretic chip comprising a polymer substrate in which a microfluidic flow channel is positioned, b. providing at least one ultrasound transducer in acoustic contact with one surface of the substrate, c. actuating the at least one ultrasound transducer at a frequency f that corresponds to an acoustic resonance peak of the substrate including the microfluidic flow channel filled with a liquid suspension, and d. providing the liquid suspension in the flow channel to perform the acoustophoretic operation on the liquid suspension. The invention further relates to an acoustophoretic device, a method of producing an acoustophoretic device, and a microfluidic system comprising the acoustophoretic device.

Abstract: The invention provides a micro scaled method and system for separating a subgroup of cells and/or particles from a mixture of different types of cells and/or particles in a suspension. The suspension is forced under pressure into an inlet and further into a pre-alignment channel wherein the suspension is subjected to a two dimensional acoustic force directed perpendicular to the length direction of the pre-alignment channel. The suspension is then forced into a second inlet and further into at least one separation channel wherein the mixture of cells and/or particles are forced towards the walls of the channel and subjected to a one dimensional acoustic force directed perpendicular to the length direction of the separation channel. Cells and/or particles having the same size and/or mass density and/or compressibility are collected through at least two outlets.

Abstract: The disclosure related to a method and system to separate a subgroup of objects from a mixture of objects present in a suspension wherein said suspension if exposed to acoustic forces acting in one or two dimensions, which forces said objects to separate from each other into groups which have similar properties in connection with size and/or mass density and/or compressibility.