How Ultrasonic Spray Coating Enables Precision Thin Film Research

In materials research, laboratory equipment plays a vital role in generating thin film coatings that exhibit the most desirable properties, whether conductive, functional or protective. Bringing a new product to market requires developing processes that are precise and repeatable in the laboratory phase, but can also be scaled to production level.

What Is Ultrasonic Spray Coating?

Ultrasonic spray coating systems were designed to close the gap, by providing research institutions and universities with tools that can take theory into practice. They use precise, high-frequency vibrations to convert liquid precursors into a uniform, low-velocity mist of precisely controlled droplets.

The result is a precision coating process that produces highly uniform thin films at micron and sub-micron thicknesses, with tight control over droplet size, flow rate and deposition parameters from the first experiment to full production. Ultrasonic atomization provides data for publication of research materials, and prepares novel materials to be used in next generation product development.

How Ultrasonic Atomization Works

Inside a Sono-Tek ultrasonic spray nozzle, piezoelectric transducers convert electrical energy into mechanical vibration at frequencies ranging from 25 to 180 kHz. Those vibrations spread liquid into capillary waves at the atomizing tip, ejecting uniform droplets typically 13 to 50 microns in diameter when atomizing water, at very low velocity.

Because atomization occurs at an open surface rather than through a small pressurized orifice, ultrasonic spray nozzles are generally less prone to clogging than conventional pressure spray systems. Their high-frequency vibrational action also provides a self-cleaning effect that helps maintain stable performance with many high-solids formulations and nanoparticle suspensions.

The droplets arrive at the substrate gently. There is almost no bounceback , no splatter, and minimal turbulence redistributing material across the coating area. What lands stays where it lands, building up a uniform thin film coating with precision that liquid-based deposition methods cannot match.

Controlling the Spray: Air Shaping Systems

Droplet generation is only half the process. Getting those droplets to land exactly where they need to, and nowhere else, requires control over the spray pattern itself.

Sono-Tek's patented air shaping technology uses low-pressure gas streams to guide the atomized mist into precise geometries, from ultra-fine lines as narrow as 0.4mm to wide, flat spray shapes covering large coating areas of unlimited widths, without the turbulence and overspray of conventional systems.

The practical result: transfer efficiency typically reaches 90 to 95%, compared to less than 50% with many conventional spray methods. For researchers working with materials that cost thousands of dollars per gram, that difference is not a minor process detail. It is the difference between a viable experiment and an unaffordable one.

Why This Matters: Ultrasonic vs. Conventional Coating Methods

The alternatives each have a fundamental limitation. Spin coating wastes up to 95% of applied material and cannot handle non-flat substrates. Dip coating offers minimal thickness control and produces uneven films on complex geometries. Conventional pressure spraying produces wide droplet size distributions, variable coating thickness, and can damage delicate layers with high-velocity impact.

Ultrasonic spray coating addresses all three limitations simultaneously: low-velocity deposition protects sensitive materials, uniform droplet size produces consistent film thickness, and high material transfer efficiency makes precious or expensive formulations viable at lab scale. The same nozzle technology is proven to easily scale for production, which means the process parameters researchers develop on a benchtop system are the same ones that go into manufacturing.

Applications: Where Ultrasonic Spray Coating Is Used in Research

The combination of precision, material efficiency, and substrate flexibility has made ultrasonic spray coating a standard tool across multiple research disciplines. The common thread is always the same: a material or device structure that demands more control than conventional deposition methods can provide.

Renewable Energy: Perovskite Solar Cells, TCO Layers, and Fuel Cell Catalyst Coatings

Next-generation photovoltaics demand coating processes that can deposit smooth, pinhole-free layers of perovskite absorbers, OPV polymers, quantum dot semiconductors, and buffer layers without the costly use of vacuum equipment and batch processing that slow development cycles. Ultrasonic spray coating delivers these layers in an automated, ambient-atmosphere process with the uniformity and thickness control that device performance requires.

The same technology extends to fuel cell research. In a 2025 study published in Nano-Micro Letters, researchers at the Korea Research Institute of Chemical Technology used a Sono-Tek AccuMist nozzle to spray-coat catalyst layers onto Nafion membranes for unitized regenerative fuel cells, achieving a round-trip efficiency of 25.7% at 2 A/cm², a result the authors described as among the best reported for that device class at low catalyst loading. The precise, repeatable catalyst deposition enabled by ultrasonic spray was a direct contributor to the performance outcome.

For solid oxide fuel cells, researchers at the Austrian Institute of Technology demonstrated in a 2025 IOP conference paper that ultrasonic spray pyrolysis using a Sono-Tek Impact Nozzle operating at 120 kHz could deposit thin, compact gadolinium-doped ceria films with ionic conductivity in line with published literature, establishing a low-cost, scalable alternative to vacuum deposition methods for solid oxide electrolyzer fabrication.

Medical Devices: Drug-Eluting Stents, Catheters, and Implantable Sensors

Medical device coating is one of the most demanding coating applications in existence. Film thickness must be precise and uniform across every device in a batch. Drug loading must be consistent to ensure predictable therapeutic release. And the coating process must be gentle enough not to degrade sensitive active ingredients during deposition.

Ultrasonic spray systems meet all three requirements. Sono-Tek's MediCoat systems combined with AccuMist and MicroMist ultrasonic nozzle technology deposit antiproliferative drug coatings onto coronary stents and drug-eluting balloon catheters with the uniformity required for clinical-grade results. The low-velocity spray causes no mechanical stress on the device or the coating, and the tight droplet size distribution, mathematically defined by nozzle frequency, ensures consistent drug loading from device to device and batch to batch.

Beyond cardiovascular applications, the same technology coats catheters, diagnostic platforms, microneedle patches, and blood collection tubes. Anywhere a soft, precise spray is needed to deposit multi-layer coatings on small, high-value devices, ultrasonic spray deposition is the coating process of choice.

Semiconductors and MEMS: Photoresist, Polyimide, and Functional Coatings

For semiconductor and MEMS devices with deep trenches, high aspect ratio features, or non-standard geometries, spin coating is commonly not adequate. Ultrasonic spray photoresist deposition using 120 kHz and 180 kHz nozzles provides the conformal step coverage that spin coating cannot deliver on complex topographies, with cleanroom-compatible systems that integrate directly into fab workflows.

Beyond photoresist, the technology deposits polyimide dielectric films, protective coatings for wafer dicing, and nanoparticle-based functional layers. The continuous ultrasonic vibration at the nozzle tip provides a built-in de-agglomeration effect, breaking apart nanoparticle clusters that form in suspension and restoring them to their individual nano-state before deposition. This ensures uniform particle distribution in the final coating and consistent electrical, optical, or mechanical performance across the substrate.

Electronics: Conductive Inks, EMI Shielding, and Flexible Substrates

Flexible electronics, printed electronics, and advanced display manufacturing all require coating processes that can handle unconventional substrates and sensitive materials at scale. Ultrasonic spray coating deposits CNTs, nanowires, and conductive inks onto flexible substrates with the same built-in de-agglomeration that makes it effective for semiconductor nanoparticle layers, producing uniform particle dispersion and consistent conductivity across the full coating area.

A 2023 study published in ACS Omega demonstrated the capability directly: researchers used a Sono-Tek 120 kHz nozzle to deposit mesoporous tungsten oxide films for supercapacitor electrodes, achieving a specific capacitance of 109.15 F/g and outperforming films produced by hydrothermal synthesis and spin coating methods.

The study also confirmed that ultrasonic spray deposition produces a linear relationship between the number of spray coats and film thickness, giving researchers precise, repeatable control over the final coating thickness through a simple process parameter.

Choosing a Laboratory Coating System: What to Look For

Not all ultrasonic spray equipment is built for laboratory use, as R&D systems need capabilities that production-scale systems don't prioritize.

Programmable Recipe Control

Reproducibility is the foundation of publishable research. A laboratory coating system needs intuitive software that allows researchers to set, save, and recall complete recipes controlling flow rate, nozzle speed, spray pattern, number of passes, and target thickness. Every parameter that affects the coating must be captured and repeatable, so that a result achieved in one experiment can be reliably reproduced in the next, and eventually transferred to a production system without re-optimization.

Minimal Material Requirements

Many of the materials being developed for next-generation devices are extraordinarily expensive. Precious metal catalyst inks, perovskite precursors, drug formulations, and specialty polymers can cost thousands of dollars per gram. A laboratory coating system that requires large volumes to operate is not a viable research tool for these applications.

Sono-Tek's ExactaCoat uses precision pumps for liquid delivery that requires as little as 5 mL to load, with remaining liquid recoverable after the run. That is not a minor convenience. For researchers working with precious materials, it is what makes the experiment possible at all.

Benchtop Footprint with Modular Flexibility

Laboratory space is finite. A coating system that requires dedicated floor space, complex installation, or a fixed configuration limits what researchers can do with it. The ExactaCoat fits on a benchtop or inside a fume hood, with full XYZ motion control, interchangeable ultrasonic spray nozzles for different droplet size requirements, and an optional inert atmosphere glovebox configuration for oxygen- or moisture-sensitive materials, perovskites, organic semiconductors, and certain catalyst formulations among them.

Scalability to Production

The ultimate test of a laboratory coating system is whether the process it produces can survive the transition to manufacturing. Sono-Tek's lab systems use the same nozzle technology as their production-scale FlexiCoat and custom coating platforms. Process parameters developed on an ExactaCoat transfer directly to production-scale systems with only minor scaling optimization. The coating quality, uniformity, and thickness control achieved at lab scale are the same ones that appear at volume, which is the only way a laboratory result becomes a manufacturable product.

Getting Started

Sono-Tek operates a fully equipped coating lab at our Milton, New York headquarters where researchers can test their specific application before committing to equipment. Coating quality can be evaluated, process parameters optimized, and proof-of-concept samples generated with direct expert support, before a purchase decision is made. For research teams working on novel materials or unfamiliar substrates, that starting point is often the fastest path from hypothesis to result.