High-Efficiency Electrospray Deposition for Sub-Plume-Scale Surfaces

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Schematic of the electrospray setup. (a) Schematic and (b) photograph of an electrospray deposition experiment. White dashed lines are provided as a guide to the eye of the plume. (c) Schematic of the improved spray system and process, highlighting different enhancements (E#). In stage 1, a negative polarity spray (E1) is sprayed directly at a large extractor ground (E2) coated in insulator (E3).  In stage 2, a grounded target with an insulating mask (E4) is placed on the extractor ground (E2). It is then sprayed by the spray solution at positive polarity which is stabilized by a focus ring (E5).

Invention Summary:

Electrospray deposition generally exhibits low efficiency when coating substrates smaller than the spray plume because accumulated surface charge repels incoming droplets and deflects them to unintended areas or even destabilizes the driving electric field. Additionally, competing conductive pathways and uncontrolled electric field geometry prevent effective droplet focusing, resulting in material waste and non-uniform coatings.

Rutgers researchers have invented a new electrospray deposition technology that overcomes the longstanding limitation of inefficient coating on substrates smaller than the spray plume. The new method strategically engineers electric field geometry and charge dissipation pathways to electrostatically focus droplets onto the intended small target. By isolating competing conductive pathways and optimizing grounding conditions, the technology achieves near-complete material utilization and highly uniform coatings. It also enables control of positioning of the payload to, e.g., the top of microneedles for drug delivery. This innovation enables precise, scalable coating of microscale devices, biomedical implants, and high-value materials while significantly reducing waste and improving manufacturing reliability.

Market Applications:

• Biomedical Device Coatings –microneedle arrays, stents, implants, and drug-delivery devices.
• Targeted deposition of functional thin films on small sensors, microchips, and microscale components without material overspray.
• Suitable for efficient deposition of high-value therapeutics, or nanoparticles onto small substrates with minimal material loss.

Advantages:

• Near-complete material utilization without material waste.
• Improved uniformity or deliberate anisotropy in thin-film formation on microscale and complex geometries.
• Provides reliable, reproducible coating of small biomedical, electronic, and advanced manufacturing components.

Publications:

•   Park, S. H. et al. Efficient electrospray deposition of surfaces smaller than the spray plume. Nature Communications 14, 4896 (2023). https://doi.org/10.1038/s41467-023-40638-7. 

Intellectual Property & Development Status: Non-provisional patent application filed in multiple territories (see WO2023177857A2). Patent pending. Available for licensing and/or research collaboration. For any business development and other collaborative partnerships, contact marketingbd@research.rutgers.edu.