With the continuous advancement of neuroscience and bioelectronics, the development of high‑performance, miniaturized, and personalized neural interfaces has become a major research focus. Traditional fabrication techniques face limitations in terms of high precision, complex structures, and material diversity, underscoring the urgent need for a more flexible, precise, and efficient micro‑ and nano‑fabrication approach. Aerosol jet printing (AJP), as an emerging micro‑ and nano‑manufacturing technology, is increasingly driving innovation in neural prosthetic devices thanks to its unique advantages.

This paper provides an in-depth overview of the applications, advantages, challenges, and future prospects of AJP technology in the design and fabrication of neural prostheses.

Principle of Aerosol Jet Printing (AJP) Technology

Aerosol Jet Printing (AJP) is a non-contact micro- and nano‑printing technique that uses an ultrasonic atomization device to convert conductive, biological, or functional materials into fine aerosol particles. These particles are then ejected through a nozzle onto a substrate surface, enabling the fabrication of high‑precision micro‑ and nanostructures.

Compared with conventional screen printing and photolithography, AJP offers the following advantages:

• High resolution (up to 10 microns)

• It can be directly printed onto flexible, soft substrates (such as elastic polymers and biocompatible materials).

• Complex manufacturing capabilities spanning multiple materials, layers, and structures

• Non-contact, low-temperature processing is conducive to the preservation and application of biomaterials.

The core processes of AJP include:

• Convert conductive powders or biomaterials into aerosol particles

• Generate fine aerosols using an ultrasonic nebulizer

• Use a high-pressure gas stream (typically air or an inert gas) to spray the aerosol onto the substrate.

• Control jetting parameters to achieve precise deposition at the micro- and nanoscale.

This process significantly enhances printing flexibility and precision, making it well-suited for fabricating high-density, multi-layer neural electrode arrays and miniature sensors.

Innovative Applications of AJP in Neural Prosthetics

01 Fabrication of High-Precision Neural Interfaces

The core requirement of neural interfaces is to achieve high-density, multipoint, and low‑damage transmission of neural signals. AJP can precisely fabricate ultrafine conductive pathways and microelectrode arrays, thereby meeting this need.

Fabrication of microelectrode arrays: AJP can rapidly print conductive traces and electrodes on flexible substrates, creating extensive, densely packed arrays for precise targeting and stimulation of the brain, spinal cord, or nerve fibers.

Multimaterial integration: By combining conductive and insulating materials, multifunctional composite structures can be engineered to enhance electrode performance and reliability.

Personalized customization: Based on the patient’s specific anatomical features, rapid personalized design is achieved, enhancing implant comfort and signal quality.

02 Development of Flexible and Soft Electronic Devices

The nervous system is an extremely soft, dynamically adaptable tissue, making it difficult for conventional rigid electronic devices to interface with it. The ability of AJP to be directly printed onto flexible substrates opens up new possibilities for developing soft electronic devices.

Flexible Sensors and Microelectrodes: By inkjet-printing metallic nanowires or carbon materials onto elastomeric substrates such as silicone rubber and thermoplastic polyurethane, neural electrodes with high flexibility and stretchability can be fabricated.

A bendable, stretchable neural puncture needle: enables a safer, more comfortable implantation approach, reducing trauma and immune rejection during insertion.

Repair and Regeneration: Design detachable, replaceable soft neural interfaces to extend device lifespan and enhance clinical treatment outcomes.

03 Precision Integration and Applications of Biosensing Materials

AJP’s capability for multi-material deposition enables the fabrication of microstructures at the micrometer scale; when combined with a variety of biocompatible materials, it paves the way for multifunctional, real-time monitoring neural prostheses.

Printing of biosensors: integrating enzymatic, electrochemical, and other sensing technologies to detect neurochemical signals, inflammatory responses, blood glucose levels, and other biomarkers, thereby enabling closed-loop control.

Synchronous Monitoring of Neural Signals and Physiological Parameters: By employing inkjet‑printed microelectrode arrays, high‑precision multi‑site, multi‑channel neural signal acquisition is achieved, enhancing signal quality and stability.

Drug Release and Regulation: Jet‑printing micro‑porous structures loaded with drugs, in conjunction with sensing data, enables localized, targeted drug delivery to facilitate nerve repair.

04 Manufacturing of Complex Systems with Multi-Material, Multi-Level Structures

AJP enables complex designs involving multiple materials, layers, and structures, providing a versatile manufacturing platform for innovative neural prosthetics.

Composite material stacking: flexibly layering conductive, insulating, and cushioning materials to create a multifunctional multilayer neural interface.

Microfluidic integration: Combining microfluidic technologies to provide miniature channels for delivering drugs or fluidic signals.

Intelligent devices: smart neural prostheses that achieve self‑sensing and automatic regulation, such as intelligent prosthetic limbs and brain–computer interfaces.

Advantages of AJP in Neural Engineering

01 High Spatial Resolution and Precise Control

AJP’s nozzles are extremely small, enabling micron‑scale precision patterning and meeting the micro‑spatial requirements of the neuronal microenvironment.

02 Highly flexible, adaptable to complex shapes

It enables direct printing on curved, arcuate, and irregular surfaces, making it particularly well-suited for the complex geometries of human biological tissues, thereby helping to improve implantation success rates and signal quality.

03 Multi-material, multifunctional integration

It supports the deposition of a variety of conductive, insulating, and biocompatible materials, meeting the multifunctional integration requirements of neural devices and accelerating both research and clinical translation.

Image and Text Guide

Figure 1. General principle of AJP technology. AJP uses a sheath gas to focus atomized microdroplets into a tightly collimated, non-contact jet. This enables printing at variable standoff distances (1–5 mm), accommodates a wide viscosity range (0.001–1 Pa·s), and reduces nozzle clogging. The system is compatible with high‑density inks and flexible substrates, making it well suited for fabricating complex, biocompatible structures on non‑planar surfaces.

Figure 2. Schematic diagram of the aerosol jet printing process. The figure illustrates five main stages: (1) Atomization—using ultrasonic or pneumatic atomizers to convert liquid ink into a fine mist; (2) Transport—conveying the aerosol toward the nozzle via a carrier gas; (3) Collimation—aligning and stabilizing the aerosol stream; (4) Pneumatic focusing—enclosing the aerosol flow with a sheath gas and narrowing it into a micron‑scale beam; (5) Deposition—depositing the atomized material onto the substrate in a precisely patterned manner.

Figure 3. Example of the AJP printing process for neural probes. (A) Conceptual schematic of mouse brain regions: prefrontal cortex, motor cortex, caudate–striatum, and hippocampal CA2/CA3. (B) Sagittal brain section showing the 3D‑printed probe shaft (red) penetrating the cortex, striatum, and hippocampus. (C) Schematic diagram of the rapid 3D‑printing principle based on AJP, used to fabricate custom neural probes and circuit interconnects. (D) Image of a 32‑channel probe during printing. (E) Schematic design of the probe, including wiring and connectors. (F) Final printed probe positioned alongside a U.S. penny for scale.

Figure 4. Neural prosthetic leg. A lower-limb amputee wears a custom‑made prosthesis whose knee and ankle components are equipped with devices for sensory feedback. An encoder in the prosthetic knee (A) measures the degree of flexion, while a sensorized insole beneath the foot collects pressure data. The sensor outputs are transmitted to an external controller, which activates a stimulator connected to a multichannel electrode array implanted in the tibial division of the sciatic nerve (B); the neural interface is situated within the nerve bundle.

Advanced microfabrication technologies, particularly aerosol jet printing and micro‑nanofabrication, hold great promise for applications in neural interfaces and bioelectronic devices. These techniques enable the rapid fabrication of high‑precision, customized neural probes and sensors, enhancing the capabilities of neural signal acquisition, stimulation, and feedback, thereby providing a robust foundation for clinical applications such as brain–machine interfaces, neural repair, and intelligent prosthetics. Looking ahead, by integrating multi‑material systems and advancing biocompatibility research, these technologies are expected to drive the development of neuroelectronic devices that are smaller, more flexible, and smarter, significantly improving outcomes in the treatment of neurological disorders and ushering personalized medicine into a new era.

Aerosol Jet Printing (AJP) technology demonstrates exceptional high precision and multi-material compatibility in the fabrication of neuroelectronic devices, enabling the efficient patterning of micron-scale electrodes and microstructures. Its outstanding spatial resolution and flexible adaptability provide robust support for the innovative development of bioelectronic devices such as soft neural interfaces and brain–machine interfaces, driving neuroengineering toward greater intelligence and personalization.