EP-4301513-B1 - ACTUATION OF MICROCHANNELS FOR OPTIMIZED ACOUSTOPHORESIS

EP4301513B1EP 4301513 B1EP4301513 B1EP 4301513B1EP-4301513-B1

Inventors

FIERING, JASON
CHRISTIANSON, Rebecca

Dates

Publication Date: 20260506
Application Date: 20220304

Claims (15)

An assembly comprising an actuation plate (830) and acoustophoresis devices (805) including a plurality of microfluidic channels (810) having a resonant frequency, the actuation plate (830) comprising: a first surface configured to be coupled to an acoustic transducer configured to operate at a predetermined frequency to generate a standing wave in the actuation plate (830); a second surface, opposite the first surface, coupled to the plurality of microfluidic channels (810); and one or more slots (850) defining one or more openings through the actuation plate, the one or more openings extending perpendicular to the plurality of microfluidic channels (810); wherein the actuation plate has a thickness selected such that a frequency of the standing wave generable in the actuation plate, by the acoustic transducer when operating at the predetermined frequency, corresponds to the resonant frequency of the plurality of microfluidic channels (810) so as to concurrently focus target particles to flow within fluid along a center of each of the plurality of microfluidic channels (810), and wherein the one or more slots (850) define one or more beams, each of the one or more beams having a width less than or comparable to a wavelength of the standing wave generable in the actuation plate by the acoustic transducer when operating at the predetermined frequency.
The assembly of claim 1, wherein the actuation plate comprises at least one of a composite material, aluminum, steel, brass, tungsten, ceramic, or silicon.
The assembly of claim 1, wherein the actuation plate is constructed from a material having a first elastic modulus, and the plurality of microfluidic channels are constructed from a second material having a second elastic modulus, different from the first elastic modulus; and optionally wherein: the wavelength of the standing wave generable in the actuation plate further depends on the first elastic modulus of the material; and the material is selected such that the wavelength of the standing wave generable in the actuation plate has a number of standing wave nodes or a number of standing wave antinodes that correspond to a number of the plurality of microfluidic channels.
The assembly of claim 1, wherein a width of the actuation plate and the thickness of the actuation plate are selected such that the wavelength of the standing wave generable in the actuation plate is large enough to accommodate each of the plurality of microfluidic channels to be positioned on a center of a respective one of a plurality of nodes of the standing wave or a plurality of antinodes of the standing wave; or wherein the actuation plate has a width selected such that the standing wave generable in the actuation plate, by the acoustic transducer when operating at the predetermined frequency, has a plurality of standing wave nodes that each correspond to a position of a respective one of the plurality of microfluidic channels.
The assembly of claim 1, wherein the actuation plate has a first elastic modulus along a first axis corresponding to a width of the actuation plate, and a second elastic modulus along a second axis corresponding to a length of the actuation plate; or wherein the second surface of the actuation plate is configured to decouple from the plurality of microfluidic channels.
A method (700) of creating actuation plates for acoustophoresis devices comprising a plurality of microfluidic channels (810) having a resonant frequency, the method comprising: identifying (702) a desired frequency to operate an acoustic transducer to generate a standing wave in an actuation plate (830); selecting (704, 706, 708) a width for the actuation plate, a thickness of the actuation plate, and a material for the actuation plate having a first elastic modulus, wherein: the thickness is selected such that a frequency of the standing wave generated in the actuation plate, by the acoustic transducer when operating at the at the desired frequency, corresponds to the resonant frequency of the plurality of microfluidic channel (810) so as to concurrently focus target particles to flow within fluid along a center of each of the plurality of microfluidic channels (810); and the width is selected such that the standing wave generated in the actuation plate, by the acoustic transducer when operating at the at the desired frequency, has a plurality of standing wave nodes that each correspond to a position of a respective one of the plurality of microfluidic channels (810); defining one or more slots (850) creating one or more openings through the actuation plate, wherein the one or more slots define one or more beams, each of the one or more beams having a width less than or comparable to a wavelength of the standing wave generated in the actuation plate by the acoustic transducer when operating at the desired frequency; and coupling (710) the acoustic transducer to a first surface of the actuation plate, and coupling (710) the plurality of microfluidic channels (810) to a second surface of the actuation plate such that the plurality of microfluidic channels extend perpendicular to the one or more openings, the second surface opposite the first surface.
The method of claim 6, further comprising: flowing a fluid comprising target particles through at least one of the plurality of microfluidic channels coupled to the actuation plate; and generating the standing wave in the actuation plate by operating the acoustic transducer at the desired frequency.
The method of claim 6, further comprising: determining a dispersion relation for vibrations in the actuation plate; and selecting the material for the actuation plate such that a density of the actuation plate, an elastic modulus of the actuation plate, and a Poisson ratio of the actuation plate satisfy the dispersion relation for the vibrations in the actuation plate, wherein the method optionally further comprises: determining a number of microfluidic channels for a microfluidic device; determining a wavelength of the standing wave in the actuation plate based on the number of microfluidic channels; and determining the dispersion relation for the vibrations in the actuation plate further based on the wavelength of the standing wave.
The method of claim 6, further comprising at least one of: positioning the plurality of microfluidic channels such that the plurality of microfluidic channels are each positioned on a center of a corresponding one of the plurality of standing wave nodes generated in the actuation plate by the acoustic transducer; and positioning the acoustic transducer at a center of the actuation plate.
The method of claim 6, further comprising decoupling the plurality of microfluidic channels from the second surface of the actuation plate.
A system, comprising: the assembly of claim 1, and the acoustic transducer coupled to the first surface of the actuation plate (830).
The system of claim 11, wherein each of the plurality of microfluidic channels have a width that is less than half a wavelength of the standing wave generated in the actuation plate; or wherein each of the plurality of microfluidic channels are positioned on a center of a respective one of a plurality of nodes or antinodes of the standing wave generated in the actuation plate.
The system of claim 11, wherein each of the plurality of microfluidic channels comprise an inlet, and are configured to receive a fluid flow comprising the target particles via the inlet; and wherein the acoustic transducer is configured to impart the standing wave in the plurality of microfluidic channels; or wherein the acoustic transducer is coupled to a center of the first surface of the actuation plate.
The system of claim 11, wherein the actuation plate has a first elastic modulus along a first axis corresponding to a width of the actuation plate, and a second elastic modulus along a second axis corresponding to a length of the actuation plate; or wherein the actuation plate has a width selected such that the standing wave generated in the actuation plate, by the acoustic transducer when operating at the predetermined frequency, has a plurality of nodes that each correspond to a position of a respective one of the plurality of microfluidic channels.
The system of claim 11, wherein the actuation plate and the plurality of microfluidic channels are each configured such that the plurality of microfluidic channels can be decoupled from the actuation plate.

Description

BACKGROUND Acoustophoresis can be used to move and manipulate small particles suspended in fluid through the application of acoustic energy. Some acoustophoresis systems employ two or more transducers coupled directly to an acoustophoresis channel and are driven out of phase. However, this can result in complicated electronics systems and unwanted secondary oscillations, especially when driving multiple channels. US2018/369815 discloses a microfluidic system based on an artificially structured acoustic field, comprising a microcavity and an ultrasonic emission device, wherein the microcavity is used to accommodate a solution containing particles, and the ultrasonic emission device is used to emit ultrasound. The system further comprises a phononic crystal plate placed in the microcavity, wherein the phononic crystal plate has an artificial cycle structure, and is used to modulate the acoustic field so as to control the particles. CN107649191 discloses a microfluidic device with specific liquid flow transmission mode and for cholera diagnosis. In particular, polydimethylsiloxane, namely PDMS, with primitive surface is selected as the substrate, a miniature ultrasonic transducer is arranged near the terminal of a sample liquid fluid of a microfluidic chip, interfacial tension is reduced by ultrasonic wave, and due to the PDMS's strong absorption of ultrasonic wave, ultrasonic intensity is rapidly decreased progressively in a short distance to form interfacial tension difference between two ends of the chip. The interfacial tension difference leads to formation of pressure difference between the two ends, and the pressure difference drives the sample liquid fluid to flow along the capillary channel towards the terminal. EP3437740 discloses an apparatus for modifying the position of particles distributed in a fluid flow in a channel, comprising a channel formed by two substrates, each of the two substrates being on opposite sides of the channel, each substrate having a preselected periodic profile pattern along a length of the channel, and a transducer, wherein one of the substrates is between the transducer and the channel, and the transducer is to generate an acoustic standing wave within the channel with at least one node or antinode positioned within the channel. EP3718634 discloses a microfluidic system including a substrate comprising an elastic material and defining a microfluidic channel. The substrate can have a first set of dimensions defining a thickness of a wall of the microfluidic channel and a second set of dimensions defining a width of the microfluidic channel. A transducer can be mechanically coupled with the substrate. The transducer can be operated at a predetermined frequency different from a primary thickness resonant frequency of the transducer. A thickness and a width of the transducer can be selected based on the first set of dimensions defining the thickness of the wall of the microfluidic channel and the second set of dimensions defining the width of the microfluidic channel. WO 2018/200652 discloses a device for the purification of a fluid by the removal of undesired particles, the device including microfluidic separation channels that include multiple outlets. The device also includes isolation slots positioned between each of the microfluidic separation channels. The device's base includes multiple acoustic transducers which in some implementations are configured to protrude into the isolation slots. The acoustic transducers are configured to generate aggregation axes within the separation channels, which are used to separate out undesired particles. SUMMARY The systems and methods of this technical solution address these issues by providing an actuation device, or plate, which can include a single plate or series of beams, having a well defined mechanical resonance with desired symmetry and frequency. This resonance is excited using a piezoelectric actuator coupled to the plate, and the plate in turn drives the acoustic stimulation of the acoustophoresis chip(s), which can include one or more microfluidic channels. The standing wave generated in the plate by the piezoelectric actuator can be tuned to match in scale to a desired number of microfluidic channels. Further, the systems and methods described herein can separate the chip design (e.g., the design characteristics of the channels themselves) from the design considerations of the piezoelectric element, allowing greater flexibility and ability to optimize. One aspect of the present disclosure is directed to an assembly comprising an actuation plate and acoustic acoustophoresis devices according to claim 1. In some implementations, the one or more slots of the actuation plate can define one or more beams. Each of the one or more beams can have a width less than or comparable to the wavelength of the standing wave in the actuation plate. In some implementations, the actuation plate can include at least one of a composite materi