Co-jet nozzle assembly and anomaly detection

A method of forming and delivering an aerosol stream, comprising:

• providing a carrier gas flow including atomized nanoparticles to a first inlet of an aerosol generator body, wherein the carrier gas flows from the first inlet to a first chamber formed in the aerosol generator body and expands within the first chamber;
• providing a sheath gas flow to a second inlet of a first outer annular flow channel formed in the aerosol generator body, the first outer annular flow channel concentrically surrounding the first chamber, wherein the sheath gas flow is directed from a second outlet of the first outer annular flow channel to aerodynamically focus the expanded carrier gas flow and form a confined aerosol ink stream within a converging section positioned between the first chamber and a first outlet of the aerosol generator body;
• delivering the aerosol ink stream from the first outlet of the aerosol generator body to a third inlet of a central conduit extending through a nozzle body, the aerosol ink stream exiting the nozzle body through a third outlet of the central conduit;
• providing a plasma working gas flow to a fourth inlet of a second outer annular flow channel formed in the nozzle body, the second outer annular flow channel concentrically surrounding the central conduit;
• applying an electric potential across a first electrode and a second electrode positioned proximate a fourth outlet of the second outer annular flow channel to ionize the plasma working gas flow and form a near-ambient temperature plasma stream, the plasma stream exiting the fourth outlet and substantially coaxially surrounding the aerosol ink stream.

A system, comprising:

• non-transitory computer-readable storage media storing instructions;
• and
• an electronic processor configured to execute the instructions to:
• receive, from a live inspection camera, an image frame capturing deposition of an aerosol ink stream onto a substrate, the aerosol ink stream being coaxially surrounded by a plasma stream, the plasma stream being at a near-ambient temperature,
• segment the image frame to define a plasma jet region, the plasma jet region corresponding to a portion of the image frame including the plasma stream,
• provide the image frame to a machine learning model to generate a pixel-level anomaly heatmap comprising a plurality of pixel values, each pixel value being indicative of a likelihood of an anomaly at a corresponding location in the image frame,
• determine a plasma jet region anomaly score based on pixel values of the anomaly heatmap within the plasma jet region,
• in response to determining that the plasma jet region anomaly score exceeds a first threshold, reduce a voltage applied to electrodes of a coaxial nozzle assembly configured to generate the plasma stream, and
• in response to determining that the plasma jet region anomaly score does not exceed the first threshold, increase the voltage applied to the electrodes.