A method of acoustophoretic printing comprises generating an acoustic field at a first end of an acoustic chamber fully or partially enclosed by sound-reflecting walls. The acoustic field interacts with the sound-reflecting walls and travels through the acoustic chamber. The acoustic field is enhanced in a chamber outlet at a second end of the acoustic chamber. An ink is delivered into a nozzle positioned within the acoustic chamber. The nozzle has a nozzle opening projecting into the chamber outlet. The ink travels through the nozzle and is exposed to the enhanced acoustic field at the nozzle opening, and a predetermined volume of the ink is ejected from the nozzle opening and out of the acoustic chamber.

A grayscale inkjet printing method including the steps of: a) supplying a pigmented inkjet ink to a grayscale print head having nozzles with an outer nozzle surface area smaller than 500 μm.sup.2 and having an acoustic resonance period ARP of not more than 5.5 μs; and b) applying a voltage wave form for ejecting pigmented inkjet ink from a nozzle of the grayscale print head within one jetting cycle; wherein the pigmented inkjet ink has a viscosity of at least 3.8 mPa.Math.s at jetting temperature and a shear rate of 1,000 s.sup.−1; wherein the voltage wave form for ejecting the largest ink droplet includes, in chronological order, a first ejecting pulse having an amplitude A1 and a second ejecting pulse having an amplitude A3 with the amplitude A1 complying with the relationship: 0.50×A3<A1<1.40×A3; and wherein a time period between the end time of the first ejecting pulse and the end time of the second ejecting pulse defines an idle time period including no other ejecting pulse, the time period having a duration between 1.5 to 2.5 times the acoustic resonance period ARP; and wherein any non-ejecting pulse having an amplitude A2 present during the idle time period complies with the relationship: A2≤0.15×A3. An inkjet printing system is also disclosed.

A liquid jetting device comprising a plurality of ejection units each of which is arranged to eject a droplet of a liquid and comprises a nozzle, a liquid duct connected to the nozzle and an electro-mechanical transducer arranged to create an acoustic pressure wave in the liquid in the duct, the device further comprising an electronic control system arranged to receive a pressure signal from at least one of the transducers and to generate a transducer control signal on the basis of the received pressure signal and to control the transducers of said plurality of ejection units to operate in a mode of operation selected from a variety of different modes of operation, wherein the control system is arranged to detect an acoustic property of the liquid of the basis of the received pressure signal and to select the mode of operation in accordance with the detected property, the control system being arranged to deliver transducer control signals to the transducers, which control signals are derived from a common basic waveform that is specified by mode parameters, each mode of operation of the device is specified by a different set of mode parameters, the waveform comprises a jetting pulse and quench pulse following on the jetting pulse, and one of the mode parameters is a time delay between the start of the jetting pulse and the start of the quench pulse.

Provided is a liquid droplet generation method capable of generating liquid droplets having a diameter of 100 .Math.m or more. The liquid droplet generation method for generating liquid droplets from a liquid layer 20 by using a plurality of transducers 18, the method including irradiating the liquid layer 20 with a plurality of ultrasonic waves from the plurality of transducers 18 to scatter primary liquid droplets 21A and 21B from the liquid layer 20, and causing the primary liquid droplets 21A and 21B being scattered to aggregate and grow into a secondary liquid droplet 22A.

Methods of ejecting droplets containing a non-Newtonian fluid by an acoustic droplet ejector can include applying a tone burst of focused acoustic energy to a fluid reservoir containing a non-Newtonian fluid at sufficient amplitude to effect droplet ejection according to a tone burst pattern. The tone burst pattern may include three discrete tone burst segments, the first tone burst segment having greater duration than the second and third segments, and third segment having greater duration than the second segment. The exact durations and amplitudes of the tone burst segments can be tuned to influence the ejection properties.

A subwavelength resonator for acoustophoretic printing comprises a hollow resonator body for local enhancement of an acoustic field integrated with a nozzle body for delivery of an ink into the acoustic field. The nozzle body has a first end outside the hollow resonator body and a second end inside the hollow resonator body, and includes a fluid channel extending between a fluid inlet at the first end and a fluid outlet at the second end. The fluid channel passes through a side wall of the hollow resonator body and includes at least one bend. During acoustophoretic printing, an ink delivered through the fluid channel of the nozzle body and out of the fluid outlet is exposed to a high-intensity acoustic field.

In a droplet ejection apparatus and a droplet ejection method using the droplet ejection apparatus, the droplet ejection apparatus includes a liquid supply unit, a nozzle and a standing wave generating unit. The liquid supply unit is configured to provide a pressure to a liquid. The nozzle is connected to the liquid supply unit through a connecting conduit, to eject the liquid with a droplet. The standing wave generating unit is configured to generate a standing wave around the nozzle at which the droplet is formed, to detach the droplet from the nozzle.

A jetting device configured to jet one or more droplets of a viscous medium through a nozzle may include an acoustic transducer configured to emit an acoustic signal that transfers acoustic waves into at least a portion of the viscous medium located in a viscous medium conduit a viscous medium conduit configured to direct a flow of the viscous medium to an outlet of the nozzle. The acoustic signal may be an ultrasonic signal. The acoustic signal may adjust one or more rheological properties of the viscous medium, based on acoustic actuation. The acoustic transducer may be implemented by an actuator of the device that is configured to move through an eject chamber to cause viscous medium to be jetted through the outlet of the nozzle as one or more droplets.

A jetting device configured to jet one or more droplets of a viscous medium through the outlet of a nozzle includes an energy output device. The energy output device is configured to direct a quantum of energy into at least a portion of the volume of the viscous medium jetted through the outlet to control a breaking of the droplet from the nozzle. The energy output device may include an acoustic transducer or a piezoelectric material or a laser emitter or a heater.

Method of ultrasound-assisted 3D bioprinting includes depositing a bioink fluid matrix containing a suspension of cells into a chamber comprising two piezo transducers on opposing ends of the chamber. The method further includes vibrating the piezo transducers to generate longitudinal bulk acoustic waves within the bioink fluid matrix such that waves from opposing piezo transducers superimpose to form a standing bulk acoustic wave to drive the cells to cluster and align along one or more nodes or nodal planes formed within the bioink fluid matrix at points of intersection of the standing bulk acoustic wave. The nodes or nodal planes are spaced apart from each other by a distance equaling half a wavelength of the standing bulk acoustic wave. The nodes or nodal planes further mimic a contour of the vibrating surfaces of the piezo transducers.