Sensing and feedback for the formation of complex three-dimensional acoustic fields

1. An apparatus, comprising:

a precursor dispenser for dispensing a precursor material into a workspace;

one or more acoustic sources configured to direct acoustic waves towards the workspace through an acoustic diffractive device to provide acoustic fields that arrange the precursor material in a three-dimensional shape in the workspace;

one or more sensors configured to detect a distribution of the precursor material in the workspace;

the acoustic diffractive device configured to alter the acoustic waves from the one or more acoustic sources to provide altered acoustic fields;

an electronic controller in communication with the precursor dispenser, the one or more acoustic sources, the acoustic diffractive device, and the one or more sensors, the electronic controller being programmed to:

determine, based on the distribution of the precursor material detected by the one or more sensors and a predetermined threshold value, that at least one deviation in the distribution of the precursor material from the three-dimensional shape in the workspace is larger than a predetermined threshold value;

in response to determining that the deviations are larger than the predetermined threshold, calculate, based on feedback parameters including the distribution of the precursor material detected by the one or more sensors, one or more altered acoustic field parameters; and

controlling, based on the calculated one or more altered acoustic field parameters, the acoustic diffractive device to dynamically adjust the acoustic fields to reduce the at least one deviation in the distribution of the precursor material from the three-dimensional shape in the workspace.

2. The apparatus of claim 1 , wherein the one or more acoustic sources comprise an array of transducers.

3. The apparatus of claim 1 , wherein the one or more acoustic sources comprise at least one transducer in combination with an acoustic diffractive device.

4. The apparatus of claim 3 , wherein the acoustic diffractive device is a variable acoustic diffractive device.

5. The apparatus of claim 4 , wherein the variable acoustic diffractive device comprises an electrorheological fluid and an array of electrodes arranged to independently provide an electric field to a corresponding portion of the electrorheological fluid in response to signals from the electronic controller.

6. The apparatus of claim 4 , wherein the variable acoustic diffractive device comprises a non-Newtonian fluid and an array of actuators arranged to independently provide a mechanical stress to a corresponding portion of the non-Newtonian fluid in response to signals from the electronic controller.

7. The apparatus of claim 4 , wherein the variable acoustic diffractive device comprises two or more microfluidic channels and a pump arranged to move a fluid into or out of a selected microfluidic channel in response to signals from the electronic controller.

8. The apparatus of claim 1 , further comprising a curing device configured to cure the precursor material in the workspace in response to signals from the electronic controller.

9. The apparatus of claim 8 , wherein the electronic controller is programmed to cause the curing device to cure the precursor material in the workspace in response to determining that the deviations in the distribution of the precursor material from the three-dimensional shape are less than a predetermined threshold.

10. The apparatus of claim 8 , wherein the curing device comprises a radiation source or a reagent source.

11. The apparatus of claim 1 , wherein the acoustic fields comprises one or more energy extrema sufficient to trap the precursor material in the three-dimensional shape in the workspace.

12. The apparatus of claim 1 , further comprising a chamber enclosing the workspace.

13. A 3D printing system, comprising:

a precursor dispenser for dispensing a precursor material into a workspace, the precursor material being curable upon exposure to a curing agent;

a curing device positioned to supply the curing agent to the workspace;

one or more acoustic sources for directing acoustic waves towards the workspace such that the acoustic waves provide acoustic fields to arrange the precursor material in a three-dimensional shape in the workspace;

one or more sensors for detecting a distribution of the precursor material in the workspace; and

an electronic controller in communication with the precursor dispenser, the curing device, the one or more acoustic sources, and the one or more sensors, the electronic controller being programmed to:

determine, based on the distribution of the precursor material in the workspace detected by the one or more sensors, that the deviations are larger than a predetermined threshold;

in response to determining that the deviations are larger than the predetermined threshold, calculate one or more altered acoustic field parameters;

supply signals, based on the calculated one or more altered acoustic field parameters, to cause the one or more acoustic sources to adjust the acoustic fields to reduce deviations in the distribution of the precursor material from the three-dimensional shape in the workspace; and

supply signals to cause the curing device to cure at least a portion of the precursor material in the workspace in response to determining that the deviations in the distribution of the portion of the precursor material from the three-dimensional shape are less than a predetermined threshold.