I. Core Research Summary

• Real-time control of magnetic filler content during the printing process.

There is no need to pre‑mix the ink; during printing, the aerosol composition of the two streams can be dynamically switched. A single thin film can be patterned into multiple gradient magnetic regions with magnetization levels ranging from 0 to 15.1 wt%, and the magnetic saturation intensity varies linearly with the filler content, enabling region‑specific, differentiated magnetic responses.

• Independent, mold-free, all-in-one Microsoft body molding

A PVA water-soluble sacrificial substrate is employed, combined with layered aerosol deposition and stepwise UV curing. Upon completion of printing, the sacrificial layer is dissolved in clean water, directly yielding a fully self-supporting flexible structure, thereby eliminating the need for cutting, bonding, and secondary assembly processes.

• Superparamagnetic Composite Flexible Material System

10-nm Fe₃O₄ nanoparticles are uniformly dispersed within a soft, elastomeric photocurable matrix; the material exhibits no remanence and no coercivity, and upon removal of an external magnetic field, it spontaneously recovers its original shape, enabling a variety of biomimetic motions such as grasping, folding, and rolling.

• Validation of Multi-Modal Magnetically Actuated Soft Prototypes

A single‑step fabrication process yields multi‑gradient biomimetic fingers, petal‑shaped actuators, a three‑finger micro‑gripper, and a rollable grasping robot. Differential magnetic properties across distinct regions enable region‑specific bending amplitudes, while an external magnetic field provides remote, wireless actuation.

• Wide ink compatibility and cross-phase blending capability

Oil-based magnetic fluids and water-based soft‑gel aerosols can be co‑blended in situ, breaking the conventional printing constraint that “liquids must be mutually soluble” and enabling compatibility with functional material systems exhibiting vastly different polarities.

II. Working Principle and Core Advantages of Dual-Component Aerosol Dispensing

(1) Complete DMAJP Dual-Print Workflow

• A PVA water-soluble sacrificial layer is spin-coated onto the substrate as a temporary support.
• Two independent atomization units: an ultrasonic chamber for dispersing magnetic nano‑ink and a pneumatic chamber for delivering photocurable polymers.
• Two streams of nitrogen carrier gas carry the atomized mist into a static mixing chamber for thorough blending, while a coaxial sheath gas focuses the single nozzle output.
• The CNC program dynamically adjusts the flow rates of two carrier gases in real time, thereby regulating the proportion of magnetic particles.
• After a single-layer deposition, in-situ UV curing is performed for 3 seconds, followed by multilayer cyclic stacking until the target thickness is achieved.
• The PVA sacrificial layer is dissolved by immersion in pure water, and the resulting substrate-free, independently actuated magnetic‑responsive soft material is peeled off.

(II) Five Unique Process Advantages (Compared with DLP, Direct Write, and Injection Molding)

• Online dynamic composition adjustment, with programmable magnetic properties per zone.

Traditional printing inks have fixed formulations, whereas this process dynamically adjusts the mist‑flow mixing ratio along the printing path, enabling a single device to support multiple actuation response zones without requiring multiple inks or repeated printing.

• Aerosol blending of immiscible solvents overcomes the limitations of liquid-phase compatibility.

Oil-based magnetic fluids and hydrophilic soft elastomers cannot be directly mixed in the liquid phase; instead, they are conveyed separately in a mist form and recombined within the nozzle, significantly broadening the range of formulation options for magnetic composite materials.

• Mold-free, assembly-free integrated manufacturing

By abandoning the conventional mold‑casting and stepwise printing‑bonding workflow, a single machine can fabricate a complete micro‑robot in one go, significantly shortening the R&D iteration cycle and reducing small‑batch manufacturing costs.

• Non-contact microscale high-precision forming

Minimum print line width: 10 μm; layer thickness is precisely controllable, enabling compatibility with millimeter-scale micro‑medical soft devices and ensuring uniform deposition on curved and complex‑shaped structures.

• Compatible with flexible substrates; the entire low-temperature UV curing process operates without high temperatures.

The curing temperature is extremely low, preserving the mechanical properties of elastic polymers, and the biocompatible resin can be directly used for the fabrication of minimally invasive medical devices.

III. Key Technological Innovations

Innovation 1: A novel additive manufacturing architecture featuring in-situ co-blending of dual aerosols

Innovative Manufacturing Scheme for a Two-Partition Programmable Magnetic Response Structure

Innovative 3‑layer sacrificial‑layer‑assisted aerosol‑based self‑supporting microfabrication

Innovative 4: Biocompatible, Low-Modulus, Light-Curable Soft Hydrogel System

Innovative 5‑step superparamagnetic nanoparticle uniform dispersion process

IV. Existing Process Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: Oil-based and water-based inks are immiscible in the liquid phase, making it impossible to pre-mix them into a uniform slurry.

Challenge 2: Highly magnetic fillers can block UV light, leading to incomplete film curing and stickiness.

Challenge 3: Conventional aerosol printing can only fabricate surface‑level thin films and is unable to produce standalone three‑dimensional soft structures.

Challenge 4: Magnetic nanoparticles tend to agglomerate, leading to non-uniform magnetic properties in the thin film.

Challenge 5: Single‑component inks can only produce uniform actuation‑induced deformation, resulting in limited biomimetic motion.

V. Future Diversified Industrial Application Scenarios

1. Minimally Invasive Medical Microsoft Robots

2. Precision Micro-Operations and Laboratory Micro-Assembly

3. Bionic Intelligence: Bionic Soft Exoskeletons

4. Miniature Underwater Cable-Free Exploration Robot

5. Laboratory-Based Rapid New Material Iteration Platform

Figure 1. a) Schematic illustration of the DMAJP process; b) Polymer ink in a plastic canister used for pneumatic atomization; c) Magnetic ink in a glass vial used for ultrasonic atomization; d) and e) Static mixing chambers for in-situ blending of two aerosols; f) Overview of the fabrication workflow for an independent magnetic soft composite structure: (i) and (ii) deposition of a water‑soluble sacrificial layer of polyvinyl alcohol (PVA) onto a glass substrate via spin coating; (iii) and (iv) cyclic alternation of DMAJP deposition and UV curing of printed patterns in a multilayer fashion; (v) and (vi) immersion of the sample in a petri dish containing deionized water to dissolve the sacrificial layer and achieve release.

Figure 2. Optical and scanning electron microscopy images at different magnifications, along with energy-dispersive X-ray (EDX) analysis results for MNP‑CFx samples, illustrating the trend in magnetic nanoparticle content as the carrier gas flow rate increases: a), e), and i) correspond to MNP‑CF50; b), f), and j) to MNP‑CF60; c), g), and k) to MNP‑CF70; and d), h), and l) to MNP‑CF80. j) shows the relationship between thickness and number of layers for the pure polymer sample MNP‑CF0 (■) and the composite material sample MNP‑CF80 (◊).

Figure 3. a) Mass fractions of MNPs in MNP aerosols at different flow rates, estimated by TGA (■) and the squid‑based method (○), respectively; b) Mass fractions of MNPs with polymer coatings, estimated by TGA (▲) and the relative mixing ratio r (□), expressed as percentages; c) Hysteresis loops of pristine MNPs; d) Hysteresis loops of DMAJP composite samples: (◊) MNP‑CF50, (■) MNP‑CF60, (□) MNP‑CF70, and (▲) MNP‑CF80.

Figure 4. a) A printed nanocomposite film comprising five distinct regions with varying concentrations of magnetic nanoparticles (MNPs): from left to right, MNP‑CF0, MNP‑CF50, MNP‑CF60, MNPCF70, and MNP‑CF80; b) Velocity profiles of the polymer and MNP aerosol during single-layer printing; c) An extended printed structure incorporating magnetic and nonmagnetic elements of different lengths, along with its corresponding velocity distribution curves during single-layer printing.

Figure 5. DMAJP‑printed multimaterial soft objects based on micron‑scale magnetic particles (MSM), featuring diverse designs and actuation functions: a) a soft object with four fingers, whose fingertip magnetic nanoparticle content increases sequentially from left to right (MNP‑CF0, MNP‑CF50, MNP‑CF60, MNP‑CF70, and MNP‑CF80); b) finger bending behavior that varies in response to a magnetic field gradient; c) a flower‑shaped object; d) petal bending motion induced by a magnetic field gradient; e) a three‑finger gripper with varying body diameters (20 mm, 15 mm, and 10 mm, from left to right); f) bidirectional bending of the gripper under opposing magnetic field gradients applied to either side of the body (with the natural resting state shown in the inset); g) a gripper prototype demonstrating the ability to lift lightweight, compressible objects (polyurethane foam blocks); h) a tetherless rolling gripper operating in both planar and folded configurations—i) after post‑curing around a spherical magnet; j) the gripper’s tetherless grasping and rolling motions.