BACKGROUND:  Droplet printing precision is important for DNA/protein microarrays. Droplet variations cause detection errors. Inkjet-based and pin-based printing can produce inconsistent droplet volume. When transferred through a nozzle, liquid droplets tend to leave residuals on the printhead after printing. Residuals cause inconsistent printed droplets, and increase the need for cleaning to avoid cross contamination between different sample liquids.

INNOVATION:  The novel method enables complete transfers of liquid droplets from a printhead to the printing surface. The effective energy at the nozzle circumference holding back the droplets is reduced, and adhesion between the liquid and print nozzle is lowered. Printhead pull-back is thereby minimized, ensuring no printhead residuals. Accordingly, the printed droplet volume consistently and accurately matches the intended droplet volume. Further, cleaning steps are minimized, which speeds printing processes. The treatment is permanent and does not require any extra step, unlike coating of the nozzle.

POTENTIAL APPLICATIONS 

• Biological assays/microarrays
• Microfluidic printing systems
• DNA solid pin "Replicators"
• Droplet-based discrete microfluidics
• Inkjet printing systems

ADVANTAGES

• Promotes complete transfer of discrete drops without residuals on nozzles
• Enables a flexible and compact system capable of printing different samples through the same nozzle
• Minimizes or eliminates cleaning steps typically needed between transfers while avoiding cross-contamination, speeding printing processes
• Improves nozzle consistency and accuracy without increasing manufacturing cost
• Integrates easily with existing nozzle technologies
• Eliminates satellite droplets, improving quality of, e.g., inkjet printing

DEVELOPMENT-TO-DATE:  The device has been fabricated, tested, and verified.

Reference: UCLA Case No. 2005-409

US Patent: 7,458,661