I. Core Research Summary

• Static mixing nozzles enable the online, uniform co-deposition of aerosols.

In a conventional T‑junction, the two spray jets deposit in laminar, stratified layers, with aluminum and copper oxide particles segregated into distinct bands. After incorporating a labyrinthine static mixing chamber, the spray jets undergo thorough turbulent mixing, resulting in uniform dispersion of the two phases within the thin film, a substantial increase in the fuel–oxidizer interfacial area, and a marked enhancement in reaction efficiency.

• Digitally Controllable Composition-Gradient Nano-Aluminothermic Thin Film

The flow rates of two carrier gases are simultaneously regulated, dynamically adjusting the nAl/nCuO deposition ratio. Within a single printing path, a continuous gradient is achieved, ranging from 43.95% Al to 91.28% Al, enabling precise control over the combustion rate and energy-release intensity of the thermite mixture.

• Integrated energetic RF antenna, microwave wireless initiation

Aerosol‑based printing is used to fabricate a 2.45 GHz silver spiral antenna, with an aluminum thermite thin film deposited in situ. Under a free-space microwave field, ignition occurs with a delay of only 129.93 ms, requiring an ignition energy of 216.26 J. No lead wires or electric detonators are needed; contactless wireless ignition is achieved by leveraging the Joule heating generated by the antenna.

• Process safety has been significantly enhanced, mitigating the risks associated with powder premixing.

Fuel, oxidizer, and ink are stored separately and mixed online only during printing, eliminating any dry‑powder blending steps throughout the process. This approach mitigates risks of static electricity and friction‑induced ignition, making it well suited for large‑scale, safe production.

• High-precision micrometer-level pattern formation, compatible with miniature devices.

The aerosol‑based process can achieve a minimum feature linewidth of 10 μm, enabling the fabrication of micro‑energetic circuits on flexible Kapton and glass substrates, thereby meeting the microscale integration requirements of miniature propulsion systems and micro‑initiation chips.

II. Complete Preparation Process and Core Advantages of Multi-Material Aerosol Jetting

(1) Complete Energetic Antenna Printing Process

• Nanometer‑aluminum and nanometer‑copper‑oxide–specific solvent‑based energetic inks are prepared separately, ultrasonically dispersed for stable storage, and delivered via two independent atomization feed lines.
• A built-in static mixing nozzle is employed, enabling thorough turbulent mixing of the two aerosol streams and simultaneous regulation of the carrier gas flow rates to achieve either fixed‑ratio or gradient‑ratio deposition.
• Nanometer-scale aluminothermic thin films are dried and formed in a low-temperature oven at 95°C.
• Switching to silver‑nanoparticle conductive ink, aerosol‑jet printing of a 2.45 GHz resonant RF antenna;
• Alumina‑thermite lines are precisely printed in the central region of the antenna, and after assembly, the microwave cavity undergoes wireless ignition testing.

( II) Five Core Process Advantages (Compared with Screen Printing, Direct Writing, and Conventional Powder Coating)

• Online mist-phase mixing significantly enhances production safety.

Fuel and oxidizer are stored separately throughout the entire process, with aerosol mixing occurring only at the moment of printing. There are no dry‑powder premixing or transfer steps, thereby eliminating the risk of electrostatic‑induced ignition accidents.

• Digitally and dynamically regulate compositional parameters to prepare gradient functional thin films with a single click.

Real-time adjustment of the flow rates of two carrier gases enables continuous variation of the thermite formulation without changing the ink, allowing flexible control over energy release and burn rate, and facilitating rapid prototyping of multi‑performance samples.

• Maskless High-Precision Direct Writing of Microscopic Patterns

Micrometer‑scale line patterning, compatible with millimeter‑scale micro‑detonators and micro‑propulsion devices; complex antennas and energetic materials are integrally formed in a single step.

• In-situ conformal integration of multiple materials, eliminating the assembly process.

The same device sequentially prints a conductive antenna and an energetic functional layer, achieving integrated formation on the substrate and thereby eliminating contact‑related issues and ignition failures that can arise from discrete component assembly.

• Compatible with wide substrates; suitable for both flexible and rigid carriers.

Both glass and polyimide flexible films can be stably deposited, making them suitable for the diverse substrate requirements of wearable initiators and airborne micro‑energetic devices.

III. Five Key Technological Innovations

Innovation 1: Innovative design of a multi-material aerosol nozzle with a built-in static mixing chamber.

Innovation 2: Technology for the Continuous Gradient Manufacturing of Energetic Materials via Airflow Control

Innovative 3‑in‑1 Aerosol‑Integrated RF–Energetic Composite Device Manufacturing Process

Innovation 4: A novel process for safely manufacturing energetic materials by replacing powder premixing with a mist‑phase mixing approach.

Innovative low-temperature, mild-forming process that does not damage the flexible substrate.

IV. Current Industry Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: Traditional dry‑powder‑mixed nano‑thermite is electrostatically sensitive and极易 self‑ignites during production.

Challenge 2: Conventional dual‑stream printing produces laminar, stratified flow with fuel–oxidizer separation and weak combustion.

Challenge 3: The combustion rate and energy release of thermite are difficult to regulate continuously and precisely, leading to slow sample iteration.

Challenge 4: The antenna and the energetic layer are manufactured and assembled separately, resulting in poor integration consistency.

Challenge 5: Traditional printing has low resolution, making it unsuitable for millimeter-scale micro‑energetic chips.

V. Future Diversified Industrial Application Scenarios

• Micro-propulsion devices for microsatellites

• Military-grade contactless wireless detonation chip

• Miniature fireworks, minimally invasive medical triggering devices

• Gradient Energetic Materials Laboratory R&D Platform

• Flexible RF sensing + trigger-integrated electronics

Figure 1. a) Schematic of the multi-material AJP system for additive manufacturing of nano‑pyrolytic materials; b) Dark-field optical microscopy image of a printed nanoscale aluminum line; c) Scanning electron microscopy (SEM) image of its surface; d) Dark-field optical microscopy image of a printed nanoscale copper(II) oxide sample; e) The corresponding SEM surface image. Insets show scintillation tubes containing various inks. Samples imaged by optical microscopy were printed on glass slides, whereas those imaged by SEM were deposited on silicon wafers.

Figure 2. a) Schematic diagram of the printing apparatus; the inset illustrates the deposition mechanism arising from the absence of in-line mixing. b) Backscattered electron image of the sample surface, with the corresponding aluminum (Al) and copper (Cu) elemental maps shown on the right. All three images share a scale bar of 50 μm. c) Backscattered electron image of the sample cross-section, accompanied by the respective aluminum and copper elemental maps; the scale bar is 1 μm.

Figure 3. a) Schematic of the printing setup using a static mixing print head, with insets showing the expected deposition morphology; b) Surface topography of the corresponding sample printed on a silicon wafer, demonstrating more uniform distribution of the constituent materials; scale bar = 50 μm; c) Cross-sectional view of the sample, including maps of aluminum (Al) and copper (Cu) distribution; scale bar = 1 μm.

Figure 4. a) AJP apparatus used to fabricate composition‑gradient samples; b) BSE images of the four regions of the gradient sample printed on a silicon wafer. The pie charts show the relative atomic compositions of each region (copper is depicted in dark blue, aluminum in light blue). Scale bar: 200 µm.

Table 1. Elemental distribution maps for the four gradient sample regions shown in Figure 4.

Figure 5. a) Oblique view of a silver‑antenna sample printed on a 0.125‑mm Kapton substrate and mounted inside a free‑space microwave cavity prior to ignition; the sample is secured to a microscope slide for precise positioning within the cavity. b, c) High‑speed camera images showing, respectively, the ignition process of a bare silver antenna (b) and a double‑layer silver–thermite antenna (c), with a 50‑ms time interval between successive frames. Scale bar: 10 mm.