I. Core Research Summary

• Low-temperature, non-destructive forming system

PLA nanofibers undergo thermal decomposition at 230°C, making conventional tubular high-temperature sintering entirely impractical. In contrast, IPL employs millisecond‑scale flashes that rapidly heat only the thermoelectric layer while keeping the substrate at a low temperature, thereby fully preserving the fibers’ flexible support structure.

• Precise and Controllable Thin-Film Formation via Aerosol Deposition

The film thickness can be linearly tuned by adjusting the number of printing layers. For samples printed 30 times, the electrical conductivity reaches 0.963 S/m, the Seebeck coefficient is −35.6 μV/K, and the power factor is 1.22 nW·m⁻¹·K⁻². At the microscale, an interwoven nanonetwork is formed, providing continuous transport pathways for charge carriers.

• Microscopic Densification Mechanism of Photonic Sintering

A single laser pulse is sufficient to remove the organic binder in the ink, while the nanowires fuse with one another, reducing interfacial porosity and contact resistance. Subsequent multiple pulses further enhance densification while preventing film cracking and substrate carbonization.

• Curved-Surface Conformity and Mechanical Adaptation

The device can conform closely to cylindrical pipes and curved bottle bodies; even after 10 bends at a 1 cm bending radius, it retains its conductivity, making it suitable for attachment to various irregular heat‑source surfaces.

• Prototype device validation of thermoelectric power generation

A single‑pair p‑Bi0.5Sb1.5Te3/n‑Bi2Te3 thermoelectric module was fabricated, delivering a stable output voltage of approximately 1 mV under a 4°C temperature difference, thereby demonstrating the feasibility of self‑powered waste‑heat harvesting.

II. Core Operating Principle of Aerosol Spraying and Its Unique Process Advantages

(1) Complete Integrated Preparation Process

• Electrospun PLA porous nanofibers are deposited on an aluminum foil substrate to serve as an insulating buffer support layer.
• Bi₂Te₃ nanowire ethylene glycol-based ink is introduced into a pneumatic atomization chamber, where nitrogen generates uniform aerosol droplets with diameters of 1–5 μm.
• The coaxial sheath airflow is focused, and the nozzle non‑contactly deposits thermoelectric thin films layer by layer on the fiber surface at a distance of 1–5 mm.
• After printing, the xenon lamp’s intense pulsed light induces instantaneous sintering, removing the solvent and densifying the nanowire network within seconds.
• Assemble p/n‑matched flexible thermoelectric power generation units using silver electrodes.

(II) Five Core Process Advantages (Compared with Blade Coating, Spin Coating, and Vacuum Evaporation)

• Low-temperature-compatible thermosensitive flexible substrate

When combined with IPL photonic sintering, the process eliminates the need for prolonged high-temperature baking. PLA, PET, and other readily biodegradable plastic fibers can stably support thermoelectric thin films, overcoming the limitations of conventional high-temperature sintering substrates.

• Curved/Special-Shaped Conformal Deposition

In non-contact printing mode, thermoelectric inks can be uniformly coated on pipes, curved surfaces, and irregular flexible substrates, making them compatible with custom-shaped heat sources in industrial equipment.

• Digital Precision Control of Film Thickness

Print layer count to linearly control film thickness, adjust thermoelectric output power on demand, and rapidly iterate formulations and thickness profiles for small‑batch production.

• High-solid nano ink with stable atomization

The 0.6 mm large‑diameter nozzle is resistant to clogging by nanowires, and the high aspect‑ratio Bi₂Te₃ dispersion enables long‑term, continuous mass production, with a consumable utilization rate far exceeding that of spin coating.

• Maskless Digital Direct Writing

Customizable thermoelectric strip graphics in CAD, enabling on-demand design of p‑type and n‑type segments without the need for metal molds, and facilitating rapid development of power‑generation modules in various sizes.

III. Key Technological Innovations

Innovation 1: A novel manufacturing process combining aerosol technology with intense pulsed photonics.

Innovative Design of a PLA Nanofiber Composite Flexible Substrate

Innovation: Precise Matching of Three-Pulse Light Parameters to the Densification Mechanism

Innovation 4: Pneumatic Atomization–Driven Regulation of Nano-Interwoven Networks

Innovative all-solution p/n pairing integrated manufacturing

IV. Existing Process Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: Conventional high-temperature sintering can melt the PLA fiber substrate.

Challenge 2: The printed film contains a large amount of organic binder, resulting in numerous pores and poor electrical conductivity.

Challenge 3: The single-layer thin film has insufficient carrier pathways, resulting in a weak output.

Challenge 4: In short‑distance, high‑intensity laser sintering, the thermal stress in the thin film is significant, leading to cracking and delamination.

Challenge 5: Pure nanowire thin films are prone to fracture upon bending, leading to resistance drift.

V. Future Diversified Industrial Application Scenarios

1. Passive monitoring sensor for industrial pipelines

2. Wearable Self-Powered Health Devices

3. Integrated power source for soft robots

4. Disposable IoT electronic tag

5. Energy-saving power-generating membrane for building envelopes

Table 1: Review of Existing Literature on Aerosol Jet Printing and High-Pulse-Energy Laser Sintering for Thermoelectric Systems

Figure 1. Schematic illustration of: (a) the aerosol jet printing process for depositing bismuth telluride nanowire ink onto a PLA nanofiber–aluminum foil substrate; (b) the high‑intensity pulsed‑light sintering of the printed bismuth telluride nanowires; (c) the complete fabrication workflow, from electrospinning PLA nanofibers on an aluminum substrate to the deposition and sintering of bismuth telluride nanowires; and (d) the operating principle of the printed thermoelectric device and its potential applications.

Figure 2. Characterization of the bismuth‑nanowire ink and the PLA nanofiber layer. (a) Viscosity profile of the bismuth‑nanowire ink; (b) Size distribution of the bismuth nanowires in the synthesized ink; (c) SEM image of the bismuth nanowires prepared by drop‑casting; (d) XRD analysis of the synthesized bismuth nanowires, consistent with the PDF card for bismuth‑nanowires having a rhombohedral unit cell structure (PDF #00–015-0863); (e) TGA and DSC results for the PLA nanofibers; (f) Confocal microscopy image of the PLA nanofibers; (g) Height map showing the surface topography of the PLA nanofibers; (h) Contact angles of deionized water and the synthesized ink on the PLA nanofibers, indicating their surface wettability.

Figure 3. (a) Schematic illustrating the operating principle of the aerosol jet printing process and the relevant process parameters; (b–i) Optical images showing the printed line width and a qualitative assessment of its quality; (b–ii) Measured line widths corresponding to different atomizer flow rates; (c–i) Optical images showing the printed line width and a qualitative assessment of its quality; (c–ii) Measured line widths corresponding to different ink flow rates; (d) Optical image of a bismuth telluride nanowire thin film printed on a PLA nanofiber substrate, with an inset showing the height distribution map and the film profile of the printed bismuth telluride nanowire film; (e) Microscopic image and height distribution map of the surface morphology of the printed bismuth telluride nanowire thin film; (f) Plot of the film thickness variation as a function of the number of printing passes for bismuth telluride nanowire thin films printed 10, 20, and 30 times.

Figure 4. (a) Schematic diagram of the IPL sintering setup, with sintering distance as the variable; (b) Optical images showing the morphology of unprinted thermoelectric thin films and samples under different sintering conditions at sintering distances ranging from 2 to 10 cm; (c) Scanning electron microscope (SEM) images illustrating the surface topography of the PLA nanofiber layer on the substrate before and after IPL sintering; (d) FTIR analysis of bismuth telluride thin films, both in their unprinted state and after IPL sintering; (e) Measurements of thin-film thickness before and after IPL sintering; (f) SEM images of bismuth telluride thin films: (i) prior to sintering; (ii) after single-pulse sintering; (iii) after three-pulse sintering; (g) Cross-sectional SEM image of an unprinted nanowire‑based thin film; (h) Cross-sectional SEM image of a nanowire‑based thin film subjected to a single IPL pulse sintering.

Figure 5. (a) Voltage output measured at the two ends of an n-type bismuth telluride nanowire under different temperature differences. (b) Photograph of a fully printed single‑pair thermoelectric device, comprising both n‑type and p‑type legs, each fabricated through 30 printing steps, along with a schematic of the experimental setup used to demonstrate voltage generation. (c) Infrared thermal imaging showing the temperature distribution during operation of the printed thermoelectric device. (d) Photograph illustrating the voltage generated across the device’s terminals. (e–i) Optical images depicting a flexible printed thermoelectric device adhered to the curved surface of a bottle; (e–ii) Thermal imaging revealing heat generated by the bottle; (e–iii) Voltage measured across the terminals of the thermoelectric device attached to the warm bottle surface. (f) Results of cyclic bending tests performed on the prepared n‑type thermoelectric thin film. (g) Images of thermoelectric energy‑harvesting devices mounted on the surface of a heat pipe for energy‑collection applications; these devices can be connected to external electronic circuits to store electrical energy.

Table 2 Thermoelectric Properties of Aerosol-Printed Sintered Bismuth Telluride