I. Abstract of the Paper’s Core Research

This study pioneered a complete set of high‑throughput combinatorial aerosol printing (HTCP) equipment and process. It employs two independent atomization channels to generate dual aerosol streams, which are pneumatically mixed in situ within the print nozzle. A mass flow controller (MFC) is used to dynamically regulate the flow rates of the two carrier gases, enabling real‑time adjustment of component ratios without the need to stop the system for ink changes or pre‑prepare inks. The system has undergone fluid dynamics simulations, high‑speed imaging, and validation across multiple material systems. The key findings are as follows:

In-situ real-time mixing core mechanism of the fog phase

Nitrogen sheath gas compresses the aerosol into two streams, leveraging the Saffman effect to enhance uniform droplet coalescence; CFD simulations confirm that increasing the sheath‑gas flow rate significantly improves mixing homogeneity. Two gradient‑printing strategies—orthogonal and parallel—are employed: the orthogonal mode is compatible with most substrates and printing speeds, achieving a spatial resolution of 25 μm.

Precise dynamic compositional regulation over a wide range

The ink flow rate exhibits a linear, monotonic relationship with the deposition thickness, and a wide range of inks—including silver, graphene, Bi₂Te₃, and polystyrene—can be stably tuned. Within a single printing trajectory, the compositional profile varies continuously and linearly, with no delamination or phase separation, enabling the one-step fabrication of fully gradient material samples.

Ultra‑strong materials with universal compatibility

It encompasses 0D metal particles, 1D nanowires, 2D two-dimensional sheets (such as MXene/WS₂), inorganic chalcogenides, oxides, biopolymers, and conductive polymers; even MXene and Sb₂Te₃, which have opposite surface charges and tend to agglomerate in the liquid phase, can be prevented from premature aggregation through aerosol‑phase isolation, yielding uniform and dense thin films.

Four Major High-Throughput Materials Preparation Paradigms

① Combined doping: A gradient‑doped Bi₂Te₂.₇Se₃ thin film with sulfur doping, in which the optimal 1 at.% doping concentration was precisely identified, exhibits a power factor that significantly surpasses that of conventional printed thermoelectric materials.

② Functionally Graded: A continuous, gradient‑type polyurethane film with soft and hard regions, featuring a smooth transition in Young’s modulus spanning two orders of magnitude.

③ In-situ reaction: GO and ascorbic acid are printed simultaneously, with gradient reduction along the printing path to yield rGO.

④ Microstructural array: A periodic multilayer micrometer-scale three-dimensional structure of Ag/MoS2, with a thickness-direction resolution on the order of hundreds of nanometers.

Low-cost, cleanroom-free high-throughput screening

A single substrate can simultaneously produce dozens of compositional samples, and a single experimental setup enables doping and compositional‑property screening, significantly shortening the new‑material R&D cycle while requiring far lower equipment investment than a vacuum‑based sputtering system.

II. HTCP High-throughput aerosol full-process workflow

Preparation of multi-component inks: Metallic materials, two-dimensional materials, polymers, and precursors are each formulated into stable dispersions, and ultrasonic defoaming ensures consistent atomization.

Dual-Path Atomization System: Two independent ultrasonic atomization generators, with two aerosol streams converging into the print head’s built-in mixing chamber;

Gas‑path coordinated control: The sheath gas focuses and compresses the atomized ink stream, while the MFC simultaneously adjusts the flow rates of the two ink streams in real time, with the program coordinating the motion of the worktable.

Two gradient printing modes: Orthogonal gradient (general-purpose) / Parallel gradient (low-speed–specific), CAD setting for compositional variation curves;

Constant-Temperature Deposition on the Substrate , low-temperature / photonic sintering and thermal curing treatments as required;

Complete characterization: SEM/EDS/Raman, thermoelectric measurements, mechanical DIC strain imaging, and optical fluorescence scanning were employed to perform structure–property analysis.

III. Five Core Process Advantages of HTCP Composite Aerosol

Adjust the mixing ratio in real time during printing—no need to pre-mix multiple ink batches.

Traditional processes require formulating dozens of fixed‑ratio pastes, whereas this technology uses only two sets of stock solutions and dynamically switches components on the fly, eliminating much of the labor involved in ink formulation and storage.

Gas-phase isolation prevents liquid-phase agglomeration of dissimilar materials.

Positive and negative charged colloids are spatially separated in the nitrogen‑gas aerosol phase and only recombine upon deposition on the substrate, thereby overcoming the challenges of agglomeration and failure associated with liquid‑phase mixing and expanding the scope of composite materials.

Micrometer-scale continuous gradient maskless direct writing

With a spatial resolution of 25 μm, compositional gradients can be smoothly transitioned along a single line, and multi‑gradient arrays can be fabricated synchronously in partitioned regions—without the need for photolithographic masks.

Universal for all material categories—compatible with inorganic, organic, and biological materials.

A single system is versatile across metals, thermoelectrics, two-dimensional materials, conductive polymers, hydrogels, and bio‑proteins, spanning the entire spectrum of energy, sensing, and biotechnology.

Low-cost, high-throughput screening without a cleanroom

Printing is carried out at ambient pressure and room temperature, eliminating the need for a high‑vacuum chamber. Small batches of materials can be rapidly prepared, with R&D costs significantly lower than those of vacuum co-sputtering or pulsed laser deposition.

IV. Five Core Technological Innovations of This Study

Innovation 1: A High-Throughput Printing System for In-Situ Dynamic Mixing of Fog Phases

An aerosol-based dual‑channel pneumatic real‑time mixing scheme, which differs from liquid‑phase premixing and traditional multi‑material printing with layered stacking, enables continuous compositional control during the printing process.

Innovative Orthogonal Gradient Normalized Printing Process 2

Addressing the deposition lag defects in parallel-mode high-speed deposition, an orthogonal strategy is adapted to all operating conditions, and a quantitative database correlating flow rate, composition, and material properties has been established.

Innovative Three-Phase Anti-Agglomeration Composite Molding Mechanism

By employing an aerosol-based nitrogen‑gas barrier to isolate mutually incompatible nanoparticles, we have overcome the material compatibility bottleneck in liquid‑phase mixing systems.

Innovation 4: A Universal Paradigm for High-Throughput Preparation of Four Major Material Classes

A single system seamlessly addresses four major R&D needs: doping optimization, functional grading, in-situ chemical reactions, and periodic microarrays.

Innovative Low-Cost Platform for Rapid Screening of New Materials

A single substrate integrates dozens of compositional samples, enabling a comprehensive performance scan in a single experiment and reducing the trial-and-error cycle for new materials from several months to just a few days.

V. Current Industry Challenges and Corresponding Solutions

Challenge 1: Conventional combinatorial deposition relies on vacuum equipment, which is costly and imposes material limitations.

✅ Atmospheric-pressure aerosol processing system—no vacuum chamber required—enabling the handling of both organic and thermally sensitive biomaterials, while significantly lowering the equipment’s entry barrier.

Challenge 2: Multi-material inks require pre‑mixing with fixed ratios, making iterative adjustments cumbersome.

✅ Dual independent atomization, dynamically adjustable flow rate via software, and one-touch generation of any continuous component—no ink cartridge changes required.

Challenge 3: Positive and negative colloids in the liquid phase readily aggregate, leading to numerous defects in the composite membrane.

✅ Gas-phase nitrogen isolation ensures that compounding occurs only on the substrate surface, thereby suppressing nanoparticle agglomeration at the source.

Challenge 4: The gradient thin film exhibits distinct layering and abrupt compositional transitions, making continuous property tuning impossible.

✅ The mist flow undergoes thorough pneumatic mixing, resulting in a smooth compositional transition across the deposited layer and continuous, gradual variations in mechanical and electrical properties.

Challenge 5: The experimental screening of new material doping and formulation ratios is labor-intensive and time-consuming.

✅ A single substrate generates a complete compositional gradient library, enabling full‑range formulation coverage in a single test and accelerating R&D through high throughput.

VI. Future Diversified Industrial Application Scenarios

1 Flexible Thermoelectric Energy Harvesting Device

Gradient-doped Bi₂Te₃-based thermoelectric thin films enable rapid screening of optimal doping formulations, facilitating the mass‑scale development of wearable body‑temperature–harvesting patches.

2 Flexible Gradient Biomedical Materials

A soft–hard continuously graded polymeric thin film that matches the mechanical properties of human skin and tendons, serving as an implantable soft‑tissue scaffold.

3 Multifunctional MEMS Sensor Array

A gradient‑structured two‑dimensional composite sensing layer enables a single chip to simultaneously detect multiple signals—temperature, force, and chemical—synchronously.

4 Catalytic High-Throughput Screening Platform

Metal/sulfide gradient catalytic thin films with rapid optimization of high‑efficiency electrocatalytic and photocatalytic composite ratios.

5 Printing Optoelectronic Device R&D Laboratory

Gradient work functions and bandgap-tuned optoelectronic thin films, along with rapid prototyping and iterative development of OLEDs and photodetectors.

Image and Text Guide

• Two (or more) inks are first atomized into an aerosol containing micron-sized droplets; the merged streams are mixed in situ within a single nozzle and, after being pneumatically focused by a co-flow sheath gas, are deposited, enabling high-throughput printing of composite materials.
• Orthogonal gradient mode exhibits strong fault tolerance and can accommodate a wide range of printing speeds; in contrast, parallel gradients are prone to deposition lag at high speeds, leading to mixing and deposition misalignment.
• Within the stable jet regime, the ink flow rate enables monotonic control of deposition thickness, making it suitable for a variety of nanoinks, including AgNWs, graphene, Bi₂Te₃, and polystyrene.
• The x–y plane offers a spatial resolution as low as approximately 20 μm and a deposition thickness as thin as about 100 nm, enabling fine compositional gradients without the need for a cleanroom.

• A dual‑ink system comprising 0D Ag nanoparticles (≈60 nm) and 2D Bi₂Te₃ nanosheets (≈1 μm), when subjected to pneumatic focusing and gradually increasing the metal/semiconductor ink mixing ratio, exhibits a distinct three‑stage morphological transition.
• EDS reveals a monotonic increase in Ag content along the printing direction, with a spatial resolution of approximately 25 μm capable of resolving distinct compositional features, and the results are reproducible across samples.
• The preparation of a single gradient membrane takes approximately one minute, and TEM reveals that, after sintering, Ag and Bi₂Te₃ form a chemically bonded nanocomposite structure.

• It can cover metals, oxides, nitrides, carbides, chalcogenides, and halides, with elements spanning the s‑block and p‑block of the periodic table (including transition metal chalcogenides and carbides).
• Nanomaterials with different dimensionalities and morphologies—0D/1D, 1D/2D, and 0D/2D—all exhibit excellent mechanical robustness, while the composite membrane features a uniform distribution of nanostructural building blocks with no phase separation.
• The shifts in Raman characteristic peak positions (approximately 1094 cm⁻¹ for chitosan and approximately 1434 cm⁻¹ for PEDOT:PSS) confirm the continuous gradient‑based transition of the polymer components.

• Sulfur-doping concentration gradients were screened within a single composite gradient film: the Seebeck coefficient increased from approximately −130 to about −213 μV·K⁻¹ (at roughly 1.0% S) and then leveled off.
• At 1.0 at.% sulfur doping, the room-temperature power factor reaches a peak of 1774 μW·m⁻¹·K⁻², significantly higher than that of most printed n-type thermoelectric materials (typically 10²–10³).
• Sulfur doping increases the effective mass of the density of states, m*_DOS, which underlies the dramatic enhancement of thermoelectric performance and enables data‑rich screening of composite materials.

• Two immiscible inks (Ag and MoS₂) are alternately deposited layer by layer to form a periodic composite structure, with the formulation designed to suppress interlayer diffusion.
• Aerosol-based low‑viscosity drag enables rapid material switching, with a sub‑micron spatial resolution of approximately 100 nm in the thickness direction—something that is difficult to achieve with extrusion or other multi‑material approaches.
• Microstructural patterning can also be applied to high-aspect-ratio 3D structures—such as 3D arrays of salt‑crystal pillars—demonstrating the structural design freedom afforded by HTCP.