What Is Droplet Dispensing?

Mention droplet dispensing and you may immediately think of lab-on-a-chip (LoC) devices. Indeed, LoC devices rely on droplet dispensing systems or pipettes to distribute liquids for disease diagnostics. However, the application of droplet dispensing extends beyond life sciences. It finds various applications in consumer electronics (home inkjet printers), optics (lens arrays for fiber optics), life sciences (LoC systems, medical inhalers) as well as electronics manufacturing (dispensing solder droplets for flip chip bonding — attaching semiconductor chips to a substrate by flipping them onto tiny solder bumps) [1]. 

Dispensing droplets manually involves using a syringe or micropipette to release individual droplets, and is common in laboratories for liquid handling. Micropipettes are engineered to deliver highly reproducible volumes and can reduce human variability, but achieving this precision requires proper technique and therefore subject to inter‑individual imprecision [2].

Automated droplet dispensing systems, in contrast, offer superior reliability by accurately jetting (drop-on-demand jetting systems) or extruding (direct ink writing systems) single discrete volumes of materials from a nozzle to a precise location. The target volume of each drop can range widely, from picoliters in microelectronics to microliters in lab applications. Achieving consistent volume is crucial in droplet dispensing for accuracy and reproducibility [3].

Droplet dispensing plays a critical role in electronic packaging. For example, advanced micro droplet dispensers use piezoelectric or magnetostrictive actuation to jet precise adhesive or encapsulant droplets [4]. This has significantly improved the consistency and placement of the smaller droplets, increasing assembly speed and supporting higher-density, miniaturized devices [5].

Another key application in electronics manufacturing is solder droplet printing for circuit assembly. One demonstrated system [6] uses a heated pneumatic printhead to directly jet molten solder droplets onto PCB pads, where they solidify to form electrical interconnects. Such droplet-based metallization methods (including solder jetting and nanoparticle ink printing) avoid the steps of reflow ovens or wire bonding, potentially streamlining electronics assembly [6].

In the optics and display industry, droplet dispensing technologies are used to fabricate fine optical structures and deposit light-emitting materials with great control. Inkjet printing of display layers has emerged as a promising alternative to vapor deposition in OLED and quantum-dot displays. Solutions of organic light-emitting or quantum dot materials are dispensed as microliter droplets into millions of pixel wells, then cured to form uniform thin films [7].

Another optical application is making microlens arrays (MLAs), used to enhance light extraction or sensing in miniaturized cameras, 3D displays, and sensors. By jetting or printing UV-curable polymer droplets to form a smooth micro-lens, droplet dispensing bypasses molding steps and allows high fill-factors over large areas, enabling rapid prototyping of optics on flat or flexible substrates [8].

In lab-on-a-chip assembly and operation, droplet-based systems precisely manipulate microliter and nanoliter droplets of fluids for assays. For example, a recent platform [9] demonstrated fully automated immunoassays by using magnetic beads to shuttle droplets between processing steps, running multiple tests in parallel on a disposable chip, and achieved sensitivities comparable to conventional lab methods. 

Unlike continuous-flow microchannels, droplet-based approaches in point-of-care testing minimize sample volume, cut assay time, and allow in situ integration of functions (mixing, incubation, detection) that would otherwise require bulky instruments. They also provide a controlled, contamination-limited environment for biochemical reactions [10].

Beyond diagnostics, droplet dispensing has a broad spectrum of expansive applications in the life sciences. In bioprinting, for example, droplet dispensing systems deposit bioink droplets containing living cells, growth factors, or other biomaterials to fabricate tissues and organoids (lab-grown miniature organs/tissues), achieving precise placement of cells at high speed [11]. This precise spatial control supports the recreation of cellular microenvironments, which is essential for studying cell-to-cell interactions, disease progression, and tissue regeneration [11].

As seen in the applications above, a wide variety of materials can be dispensed as droplets, from metals and functional nanomaterials to polymers and bioinks. However, dispensing materials at micro to nanoliter scales comes with several important considerations.

• Clogging: Dried residue from volatile solvents or particulate matter in the fluid can block nozzles. In addition to frequent cleaning, it may be necessary to adjust material viscosity using additives or by changing the temperature.
• Inconsistency in placement and volume: Droplet volume can drift due to changes in printing parameters (e.g., drawback force) [12]. Air currents, static charge on the substrate, or inconsistent drop velocities can also affect placement. Choosing a high-precision droplet dispenser and implementing environmental controls, such as using an enclosure, are critical for consistent results.

To learn more about dispensing best practices, check out How to Dispense Adhesives.

Droplet dispensing is increasingly important in electronics manufacturing and the life sciences, enabling precise miniaturization. Recent work [13] suggests that adaptive intelligent control will be key to maintaining consistent droplet formation and ejection characteristics, and future advances may allow dispensers to self-tune to different liquids for optimal performance.

Ready to learn more about materials dispensing? Explore these resources:

• Blog: What Is Dot Dispensing?
• Blog: What Are Precision Fluid Dispensing Systems?
• Application overview: Solder Paste Printing

Looking for proof-of-concept of your droplet dispensing applications? Book a meeting to speak with one of our technical representatives.

[1] Lindemann, T., & Zengerle, R. (2008). Droplet Dispensing. Encyclopedia of Microfluidics and Nanofluidics, 402–411. https://doi.org/10.1007/978-0-387-48998-8_361. 

[2] Lippi, G., Lima-Oliveira, G., Brocco, G., Bassi, A., & Salvagno, G. L. (2017). Estimating the intra- and inter-individual imprecision of manual pipetting. Clinical Chemistry and Laboratory Medicine (CCLM), 55(7). https://doi.org/10.1515/cclm-2016-0810. 

[3] Nikapitiya, N. Y. J. B., Nahar, M. M., & Moon, H. (2017). Accurate, consistent, and fast droplet splitting and dispensing in electrowetting on dielectric digital microfluidics. Micro and Nano Systems Letters, 5(1). https://doi.org/10.1186/s40486-017-0058-6. 

[4] Zhou, C., Li, J. H., Duan, J. A., & Deng, G. L. (2015). The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier. Scientific Reports, 5(1). https://doi.org/10.1038/srep18294. 

[5] Nature Research Intelligence. (n.d.). Fluid Dispensing and Microelectronics Packaging. https://www.nature.com/research-intelligence/nri-topic-summaries/fluid-dispensing-and-microelectronics-packaging-micro-82301. 

[6] Shu, Z., Fechtig, M., Florian Lombeck, Breitwieser, M., Zengerle, R., & Koltay, P. (2020). Direct Drop-on-Demand Printing of Molten Solder Bumps on ENIG Finishing at Ambient Conditions Through StarJet Technology. IEEE Access, 8, 210225–210233. https://doi.org/10.1109/access.2020.3040035. 

[7] Xiong, J., Chen, J., Li, Y., Yue, X., Fu, Y., & Yin, Z. (2025). Large-area OLED substrate printing path planning method based on multi-head GAT imitation learning to solve partitioned integer programming. Scientific Reports, 15(1). https://doi.org/10.1038/s41598-025-08355-x.

[8] Zhong, L., Liu, W., Gong, H., Li, Y., Zhao, X., Kong, D., Du, Q., Xu, B., Zhang, X., & Liu, Y. J. (2025). Electrohydrodynamically Printed Microlens Arrays with the High Filling Factor Near 90%. Photonics, 12(5), 446–446. https://doi.org/10.3390/photonics12050446. 

[9] Hu, X., Gao, X., Chen, S., Guo, J., & Zhang, Y. (2023). DropLab: an automated magnetic digital microfluidic platform for sample-to-answer point-of-care testing—development and application to quantitative immunodiagnostics. Microsystems & Nanoengineering, 9(1), 1–12. https://doi.org/10.1038/s41378-022-00475-y. 

[10] Trinh, T. N. D., Do, H. D. K., Nam, N. N., Dan, T. T., Trinh, K. T. L., & Lee, N. Y. (2023). Droplet-Based Microfluidics: Applications in Pharmaceuticals. Pharmaceuticals, 16(7), 937. https://doi.org/10.3390/ph16070937.

[11] Ng, W. L., & Shkolnikov, V. (2024). Jetting-based bioprinting: process, dispense physics, and applications. Bio-Design and Manufacturing, 7(5), 771–799. https://doi.org/10.1007/s42242-024-00285-3.

[12] Wang, W., Chen, J., & Zhou, J. (2016). An electrode design for droplet dispensing with accurate volume in electro-wetting-based microfluidics. Applied Physics Letters, 108(24). https://doi.org/10.1063/1.4954195. 

[13] Jiang, J., Chen, X., Mei, Z., Chen, H., Chen, J., Wang, X., Li, S., Zhang, R., Zheng, G., & Li, W. (2024). Review of Droplet Printing Technologies for Flexible Electronic Devices: Materials, Control, and Applications. Micromachines, 15(3), 333. https://doi.org/10.3390/mi15030333.