I. Core Research Summary

• All‑room thermal aerosol integrated molding, with a dual‑function device featuring a switchable architecture.

The entire fabrication process requires no high-temperature baking, ensuring that the PI flexible substrate remains free from thermal damage throughout. A silver electrode architecture enables low-power resistive random-access memory (ReRAM), while a transparent CNT electrode configuration can serve as a 660 nm visible-light photodetector. Moreover, the same cross‑array architecture supports both core functionalities.

• High-Performance Resistive Switching Properties of WSe₂

It requires no forming initialization; the switching voltage is below 1 V, and the on/off current ratio reaches two orders of magnitude. By tuning the current‑limiting threshold, it can switch between volatile and nonvolatile storage modes, with a minimum operating power consumption of only 16 μW, making it well suited for low‑power flexible devices.

• High-sensitivity visible-light photoelectric detection performance

The CNT transparent electrode enables light to penetrate into the WSe₂ active layer; under 660 nm laser illumination, it achieves a maximum photoresponsivity of 1 A/W. An external bias voltage allows independent tuning of the detector’s sensitivity, enabling effective amplification of weak optical signals, with a response time on the order of milliseconds.

• Excellent flexible mechanical reliability

The device exhibits a bending radius as low as 5 cm, and after repeated deformation, its switching characteristics and photoelectric response show no significant degradation, making it well suited for conformal integration in curved surfaces and wearable devices.

• Digital maskless mass fabrication capability

The ultrasonic–pneumatic dual‑atomization module is compatible with three types of inks—WSe₂, silver, and CNT—offering a controllable line width of 70–80 μm. Array layouts can be exported directly from CAD, eliminating the need for photolithography masks, making it ideal for rapid prototyping and iterative development in flexible electronics.

II. Complete Preparation Process Flow and Core Technological Advantages of Aerosol Sprays

(1) Complete Dual-Mode Device Printing Process

• The 100 μm Kapton polyimide substrate is cleaned to remove contaminants and left at room temperature pending further processing.
• Pneumatic atomization of silver nanoparticle ink, printing of the underlying metal electrodes, followed by localized low-temperature sintering using an 830 nm laser.
• Ultrasonic atomization is used to prepare a low-concentration WSe₂ ethanol ink, which is then deposited in 30 layered stacks to form a 300-nm-thick two-dimensional functional thin film.
• Choose one of two options: print the top-layer silver electrode or the transparent CNT electrode, thereby completing the MIM crossbar array.
• The electrical probe station and the 660 nm laser source were used to characterize the storage and photoelectric response properties, respectively.

(II) Five Core Process Advantages (Comparison of Lithography, Inkjet, and Vacuum Coating)

• Manufactured entirely at room temperature, with zero thermal damage to the flexible PI substrate.

There is no high-temperature sintering or vacuum evaporation step; only laser‑induced, localized heating of the silver traces is employed. The ultra‑thin polyimide film remains deformation‑free and does not become brittle, making it compatible with a wide range of thermally sensitive flexible substrates.

• Multi-ink dual‑atomization system compatible with two-dimensional materials and conductive electrodes.

Ultrasonic atomization is suitable for low-concentration two-dimensional WSe₂ suspensions, while pneumatic atomization handles high-viscosity silver/CNT conductive inks, enabling a single device to perform integrated printing of multilayer heterostructures.

• Micrometer-scale cross-array high-precision molding

The electrode linewidth is stable at 70–80 μm, with well-defined edges in the vertical cross‑array; a 30‑layer stack of WSe₂ thin films exhibits continuous, defect‑free coverage, effectively eliminating device leakage and short‑circuit issues.

• Non-contact conformal printing adapted to curved flexible substrates

Aerosol–1 to 5 mm—tolerant working distance; except for planar PI films, storage‑sensing arrays can be directly printed on curved wearable substrates, overcoming the limitations of planar lithography.

• Maskless Digital Rapid Development

No photomask or vacuum chamber is required; by adjusting the dimensions of the cross‑array, new device prototypes can be fabricated on the same day, significantly shortening the R&D cycle for two-dimensional material optoelectronic devices.

III. Five Key Technological Innovations

Innovation 1: Room-Temperature All-Printed WSe₂ Dual-Mode Cross-Array Architecture

Innovative Design for Functional Switching of Two-Electrode Materials

Innovative 3: A Low-Voltage Resistive Switching Mechanism Without Initialization

Innovation 4: Transparent Carbon Nanotube Light-Transmitting Electrode Solution

Innovative Uniform Multilayer Aerosol Deposition Process for Two-Dimensional Materials

IV. Existing Process Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: Two-dimensional WSe₂ ink tends to aggregate, and single-layer films are prone to leakage and short circuits.

Challenge 2: Conventional semiconductor processing at high temperatures damages flexible PI films.

Challenge 3: Metal electrodes are opaque, leading to low light absorption efficiency in two-dimensional optoelectronic devices.

Challenge 4: Most resistive‑switching devices require high‑voltage initialization, leading to a complex drive circuit.

Challenge 5: Lithography can only process planar, rigid wafers and is unable to accommodate curved‑surface wearable integration.

V. Future Diversified Industrial Application Scenarios

1 Flexible Electronics for Wearable Health Monitoring

2 Curved-Surface Smart Wearable Device

3 Soft-Robotics Biomimetic Sensing Skin

4 Ultra-thin Flexible IoT Tags

Figure 1. a) Schematic illustration of the WSe₂ cross‑array device architecture for resistive random-access memory (ReRAM) and photodetection, along with the materials used in each device; b) Fabrication process flow; c) Physical photograph of the device array and an enlarged micrograph of one individual device (with relevant structures labeled).

Table 1. Process Parameters of the Aerosol Jet Printing Technique Used

Figure 2. a) Optical and scanning electron microscope images of the WSe₂ printed layer after five printing cycles, showing a sparse material distribution; b) Variation of average thickness with the number of printing cycles; c) XRD pattern of the fabricated WSe₂, indicating random orientation; d) Raman spectrum of WSe₂, suggesting a structure more akin to bulk material, in contrast to exfoliated few-layer WSe₂ (approximately 2 nm thick).

Figure 3. a) As shown in the legend, WSe₂ devices employing Ag–Ag, Ag–CNT, and CNT–CNT electrodes were subjected to DC sweep measurements, revealing ReRAM characteristics; b) Unipolar switching behavior of the Ag–Ag device under a set current of 2 µA.

Figure 4. a) DC sweep curves of the Ag–Ag device at different current compliance levels (up to 50 µA); b) Extracted relationships between HRS and LRS resistance states as a function of increasing current compliance; c) Photographs demonstrating that the device retains functionality even when bent to a 5 cm radius.

Figure 5. Benchmark curve comparing the performance of the flexible storage devices studied herein with that of WSe₂-based devices.

Figure 6. I–V characteristics of the WSe₂ photodetector measured at a wavelength of 660 nm under varying light intensities (the corresponding light intensity values are indicated in the figure legend).

Figure 7. a) Shows the extracted photoresponse characteristics of the light sensor under applied bias conditions, demonstrating its tunability; b) Displays the time‑response curves of the light sensor at different illumination intensities.

Figure 8. Performance comparison table of the flexible optical waveguide and the WSe₂ photodetector in this study, demonstrating that both exhibit comparable photoresponse across the visible spectrum.