I. Core Research Summary

• Integrated gold/ITO dual-mode sensing structure, with no signal interference between channels.

The bottom layer features an aerosol‑printed gold strain gauge, while the top layer comprises a cross‑deposited ITO electrode; the gold–ITO interface naturally forms a thin‑film thermocouple. Strain resistance is measured in AC mode, and the Seebeck thermoelectric voltage is acquired in DC mode. These two signals are independently separated, eliminating the need for complex decoupling algorithms, thereby enabling simultaneous, real‑time acquisition of temperature and strain in the same region.

• Excellent high-temperature resistance and stability, with a maximum continuous operating temperature of 540°C.

After 7 days of high‑temperature aging at 540°C, the sensor exhibits no performance degradation. The thermocouple has a thermoelectric power of 55.64 μV/°C, and the strain gauge’s gauge factor is 2.54, both surpassing those of conventional nickel–copper commercial strain gauges. Across the entire temperature range, strain measurement errors are extremely small, and the device incorporates built-in in‑situ temperature compensation to eliminate the influence of high‑temperature resistance drift.

• Micrometer-level high-precision multi-material layered manufacturing

The aerosol‑based printing achieves a minimum line width of 10 μm, with a strain‑gauge wire pitch of 88.51 μm; the gold film thickness is approximately 3.19 μm, and the ITO electrode thickness is about 14.31 μm. After air‑annealing at 800 °C, the resulting thin film exhibits dense, conductive properties, with a gold conductivity of 1.9 × 10⁷ S/m and an ITO conductivity that remains stable at 150 S/m.

• In-situ manufacturing of curved conformal structures, eliminating the need for post‑fabrication patching.

Stainless steel and alloy components are coated only with a ceramic insulating primer; aerosol‑based printing is used to deposit sensing circuits directly on flat surfaces, curved welds, and complex curved geometries. The thin film exhibits tight thermal coupling with the substrate, resulting in thermal conductivity that far exceeds that of adhesive‑bonded sensors.

• Fully digital, maskless rapid iteration

With CAD, strain‑gauge and thermocouple layouts can be modified with a single click; gold and ITO inks can be rapidly switched for atomized printing; and a complete set of sensor prototypes can be fabricated in just a few hours, significantly shortening the R&D cycle for new high‑temperature sensing devices.

II. Preparation Process and Core Technological Advantages of the Complete Dual-Mode Sensor for Aerosol Spraying

(1) Complete Printing Process for High-Temperature Dual-Mode Sensors

• The stainless steel substrate is ground and cleaned, then spin-coated with a 94 μm-thick ceramic insulating layer; subsequent segmented high-temperature curing isolates the metal substrate from conductive interference.
• Ultrasonic atomization of gold nanoparticle ink, CNC‑controlled printing of serpentine strain gauges, and layer‑by‑layer stacking to ensure a dense thin film;
• Switch to ITO nano‑ink, perform cross‑printing of thermocouple electrodes, and form the temperature‑sensing junction at the Au/ITO intersection.
• The entire device was subjected to air sintering in a tube furnace at 800°C for 2 hours, enabling nanoparticle fusion and enhancing high-temperature oxidation resistance.
• The cantilever beam calibration platform and the high-temperature muffle furnace have completed full-range strain and temperature calibration tests spanning 25–540°C.

(II) Five Core Process Advantages (Comparison of Screen Printing, Lithography, and Surface-Mount Sensors)

• In-situ integrated molding of two materials eliminates the need for separate patch‑on‑substrate processes.

The same device enables continuous printing of both strain‑sensing and temperature‑sensing circuit layers, featuring an integrally molded dual‑mode sensing unit that eliminates the risk of delamination caused by high‑temperature aging of adhesive used in chip‑on‑board mounting.

• Conformal deposition on curved, freeform components, tailored for complex industrial parts.

Aerosol: 3–5 mm safe spray distance; arc-shaped blades, pipe welds, and the outer surfaces of irregular pressure vessels can be directly printed. Traditional patch sensors are difficult to adhere to and suffer from an air insulating layer.

• Micrometer-level high-precision micro-grating array, with a significant improvement in spatial resolution.

10-μm fine lines enable the fabrication of high-density micro-sensor arrays, allowing precise detection of localized microcracks and hotspots, whereas conventional patch-type strain gauges are bulky and feature sparse measurement points.

• High-temperature compatible ink formulation; exhibits excellent oxidation and corrosion resistance after sintering.

A dual‑system nanoink comprising gold and ITO, sintered at 800°C to form a stable structure, exhibits long‑term stability under operating conditions of 540°C. In contrast, carbon‑based and silver‑printed sensors are highly susceptible to oxidation and failure at elevated temperatures.

• Digital, low-cost, rapid prototyping—no photomask required.

No need to fabricate metal or ceramic masks—simply adjust the design files to reconfigure the sensor layout, enabling rapid validation of sensors across multiple operating conditions and specifications, thereby significantly reducing R&D costs.

III. Five Key Technological Innovations

Innovative 1‑Gold/ITO Dual-Ink Aerosol Stepwise Printing Integrated Dual-Mode Sensing Architecture

Innovation 2: High-Temperature Erasable Signal Separation and Detection Scheme

Innovative 3800°C air-sintered dense nanofilm high-temperature stabilization process

Innovative 4-Surface Curved Thermal-Coupling Optimized Conformal Sensing Design

Innovative General-Purpose High-Temperature Multi-Material Aerosol Manufacturing System 5

IV. Existing Process Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: Traditional strain gauges and thermocouples are bonded separately, leading to adhesive failure at high temperatures and significant measurement errors.

Challenge 2: Conventional silver/carbon‑printed thin films undergo rapid oxidation at 500°C, resulting in the loss of their sensing functionality.

Challenge 3: Lithography and screen printing can only perform planar processing, making it impossible to deploy sensors on curved welds or turbine blades.

Challenge 4: A single sensing element cannot distinguish between temperature-induced drift and actual strain, leading to measurement distortion at high temperatures.

Challenge 5: Multi-material sensors require multiple lithography masks, resulting in a redesign cycle that can extend to several weeks.

V. Future Diversified Industrial Application Scenarios

1. Online Health Monitoring of Aero‑Gas Turbine Blades

2. Monitoring of High-Temperature Piping and Pressure Vessels in Thermal and Nuclear Power Plants

3 High-Temperature Hydraulic Components for Heavy Construction Machinery

4. High-Temperature Thermal Structural Inspection of Spacecraft

5. Rapid Prototyping Platform for Extreme Sensing Laboratories in Universities

Figure 1. Schematic illustration showing: (a) the preparation of the stainless steel substrate and the blade‑coating process for depositing the dielectric layer on the substrate; (b) AJP of the multimode sensor on the stainless steel substrate (non‑proportional display); (c) an optical image of the printed sensor, comprising two thermocouples (gold–ITO junctions) and a strain gauge (made of gold), along with high‑magnification views of the temperature‑sensor region and selected areas of the strain‑sensor region; (d) the average line width across the various regions of the printed sensor.

Figure 2. Scanning electron microscope (SEM) images of gold films fabricated by aerosol jet printing and ITO films sintered at 800°C: (a) Top‑surface morphology of the gold film; (b) Top‑surface morphology of the ITO film.

Figure 3. (a) Thermoelectric voltage response of a printed Au/ITO thermocouple during heating–cooling cycles; (b) Stability of the thermocouple over three consecutive measurements; (c) Temperature-dependent thermoelectric voltage output curves for three sensors fabricated under identical conditions.

Figure 4. Simultaneous measurements of temperature and strain at ambient conditions: (a) Shows three independent measurement sets from the same sensor, demonstrating the stability of the printed sensor; (b) Presents the measurement results from three different sensors.

Figure 5. Temperature and strain are simultaneously measured under three different conditions to demonstrate the stability of the dual-mode sensor at the following temperatures: (a) 140°C, (b) 285°C, (c) 440°C, and (d) 540°C.