Process Physics, Atomization and Film Formation Research: 59 Peer-Reviewed Studies (2001-2026)

How droplets become films: the process physics behind every ultrasonic spray application

For the atomization physics behind every study here, capillary waves, cavitation and why viscous liquids resist, see How Ultrasonic Spray Nozzles Work. Papers marked Open access, no paywall can be read free of charge on the publisher's site; a Free copy link goes to the authors' own version in a university or government repository.

Organic electronics, displays and photovoltaics

Ultrasonic nozzles deposit PEDOT:PSS, organic-semiconductor inks, light-emitting polymers, perovskite precursors and VO2 nanoinks as thin multi-pass coatings, from tens of nanometers to micrometers, with thickness, loading and morphology set independently. Fine droplets, low spray momentum and programmed raster motion control roughness, coffee-ring formation, crystallization and large-area uniformity, and the process scales to automated XY and roll-to-roll coating. See also the perovskite thin-film page.

Fuel cells, electrolysis and electrochemical devices

Here the nozzle is a precision applicator for catalyst inks and electrolyte precursors. Platinum/carbon-ionomer inks sprayed onto membranes or gas-diffusion layers cut precious-metal loading and improve catalyst distribution. Droplet size, ink rheology and pass count set catalyst-layer porosity and morphology, building a porous layer rather than a dense film. Acoustic agitation at the nozzle limits agglomerates, though ink dispersion chemistry still matters. See also the gas diffusion electrodes application note.

Spray pyrolysis, ceramics, oxides and nanoparticle synthesis

In spray pyrolysis and oxide-film work the nozzle turns precursor solutions into repeatable droplets that act as individual reactor volumes, carried through a hot zone to form particles or onto a heated substrate to form semiconductor and ceramic films. Droplet diameter, precursor concentration, residence time and temperature govern particle size, morphology, agglomeration and crystallinity. Acoustic agitation at the nozzle reduces agglomerates in ceramic suspensions, and incremental deposition preserves porosity in products such as zeolite films. A 2022 self-driving-laboratory study used the same route to spray-coat palladium by combustion synthesis at 191–226 °C, with conductivity comparable to sputtered films. The table opens with a 1999 pneumatic-spray baseline (Bisht et al.), included for the transparent-conducting-oxide data a low-E glass process is measured against; it is not an ultrasonic study and is not counted in the 59. See also the spray pyrolysis page.

Medical devices, biomaterials and analytical sample preparation

Ultrasonic spraying is used for conformal, dose-controlled deposition on complex biomedical surfaces — sirolimus/polymer coatings on coronary stents and bioresorbable scaffolds, MALDI matrix deposition, bioactive coatings on magnesium, and barrier layers on biodegradable polymers. The shared advantage is a low-momentum fine spray that builds thin layers by repeated passes, so drug dose is tuned through concentration, flow rate and layer count without changing device geometry.

Food, pharmaceutical powders and microencapsulation

The nozzle acts as a droplet generator upstream of spray drying, vacuum drying and spray freeze-drying. The initial droplet population strongly influences dried-particle diameter, porosity, powder morphology, encapsulation efficiency, protein and probiotic stability, and pulmonary aerosol performance. Ultrasonic atomization is especially attractive where narrow droplet distributions and gentle low-temperature processing help preserve sensitive materials. Spray-dried particles are also a case where retained porosity, not a dense product, is the goal, and the initial droplet population sets that microstructure.

Carbon nanomaterials, batteries, composites and functional surfaces

These papers place nanoparticles, graphene and carbon-nanotube dispersions, battery active materials and functional resists onto fibers, textiles, polymer films, additively manufactured parts and non-planar optics. Multi-pass deposition raises loading incrementally while maintaining conformality and limiting runoff. Recurring concerns are suspension stability, surface wetting, porous-substrate penetration and scalable automated coating of three-dimensional surfaces. Acoustic agitation at the atomizing surface reduces agglomerates in graphene and silicon nanoparticle suspensions, but no nozzle rescues an unstable formulation, so dispersion chemistry upstream still decides the outcome.

MXene and 2D nanomaterial films

MXenes such as Ti₃C₂Tₓ are processed almost exclusively from aqueous colloidal dispersions of micron-scale flakes. That feedstock, low in viscosity and solids, shear-sensitive and expensive, is exactly what ultrasonic atomization handles well: no orifice to clog, low droplet velocity so flakes lie flat rather than splash, a narrow droplet size distribution for uniform film build, and high transfer efficiency for costly inks. The sources below show spray-coated MXene films performing as transparent conductors, EMI shields, antennas, solar-cell electrodes and membrane layers, and include the first industry-scale demonstrations using ultrasonic spray.

This cluster was compiled in September 2026 as a supplement to the 59-study map above and is not counted in it. Each entry gives the deposition method its authors state: only sources that name the atomizer are described as ultrasonic spray, and the rest are listed as spray-coated. All of this work was done by the cited groups on their own equipment. The companion white paper, Ultrasonic Spray Deposition of MXene (Ti₃C₂Tₓ) Thin Films, draws a starting process window from these sources.

Cross-cutting research connections