Imagine wearing a robotic hand that can actually "feel" when your skin stretches, just like a real human hand. Or picture a prosthetic limb that sends natural nerve-like signals to the brain while using very little power. This futuristic idea is now much closer to reality thanks to a breakthrough by researchers led by Lee, who have successfully created a 3D-printed artificial sensory nerve that mimics one of the body's most important touch sensors.
Their innovation combines neuromorphic technology, 3D printing, and advanced smart materials to create an artificial nerve capable of detecting stretching and converting it into electrical signals similar to those used by the human nervous system. The technology could transform prosthetic limbs, soft robots, wearable electronics, and future human-machine interfaces.
What Are Neuromorphic Systems?
Neuromorphic systems are electronic devices designed to work like the human brain and nervous system. Instead of processing information in the same way as traditional computers, they copy how biological neurons communicate using electrical pulses.
One of the biggest advantages of neuromorphic systems is their extremely low power consumption. Human brains perform billions of operations every second while consuming only about 20 watts of power. Engineers want electronic devices to become just as efficient.
Another major benefit is edge computing, where data is processed directly inside the sensor instead of being sent to a distant computer. This makes devices faster, more energy-efficient, and capable of responding instantly.
Why Artificial Sensory Nerves Matter
Our body constantly collects information from the environment through specialized sensory nerves. These nerves allow us to detect pressure, temperature, vibration, pain, and stretching.
The afferent nerves are responsible for carrying this sensory information from our skin and muscles to the brain. Whenever you touch an object or move your fingers, these nerves send electrical pulses that tell your brain exactly what is happening.
Scientists have spent years trying to build Artificial Afferent Nerves (AANs) that can imitate this natural process.
Such artificial nerves could allow:
Advanced prosthetic limbs with realistic touch sensation
Soft robots that safely interact with humans
Smart wearable health devices
Better human-machine interfaces
Future bioelectronic medical implants
The Missing Piece: Feeling Skin Stretch
Previous artificial nerves mainly copied one type of human touch receptor called the Slowly Adapting Type I (SA-I) receptor.
SA-I receptors mainly detect static pressure, such as pressing your finger against a table.
However, human skin also contains another important receptor called the Slowly Adapting Type II (SA-II) receptor.
SA-II receptors detect skin stretching.
This function is extremely important because it gives our brain information about body position and movement, a sense known as proprioception. Without proprioception, simple tasks like walking, holding a cup, or typing would become extremely difficult.
Until now, creating artificial SA-II nerves has been challenging due to complicated manufacturing methods.
A New Hybrid 3D Printing Technique
To solve this problem, Lee and the research team developed a completely new manufacturing process using hybrid direct-write 3D printing.
Instead of building each electronic component separately and assembling everything manually, the researchers printed most of the system directly.
Their method combines:
Soft printable materials
Stiff structural materials
Conductive inks
Surface-mounted electronic components
A custom stretch-sensitive material
The process allows rapid fabrication of complex artificial nerve systems while reducing manufacturing complexity.
This also makes future designs easier to modify and prototype.
A Special Stretch Sensor
One of the most innovative parts of the artificial nerve is its quantum tunneling strain sensor.
Normally, quantum tunneling composites change their electrical resistance when stretched or compressed.
However, traditional versions often suffer from two major problems:
Limited stretch range
Hysteresis, where the material does not immediately return to its original electrical state
The researchers solved both issues by adding oil to the composite material.
This simple modification produced major improvements.
The new sensor can:
Stretch more than 50%
Reduce hysteresis significantly
Change electrical resistance by more than one million times (over six orders of magnitude)
This enormous resistance change makes it much easier for the artificial nerve to accurately detect even subtle stretching movements.
How the Artificial Nerve Works
The printed artificial nerve contains a tiny electronic circuit known as a ring oscillator.
When the stretch sensor detects movement, its resistance changes.
That resistance controls the ring oscillator, which then generates electrical pulses.
These pulses closely resemble the action potentials produced by biological nerves.
Just like real sensory neurons, the pulse frequency increases as the amount of stretching increases.
During testing, the artificial nerve generated signals ranging from:
0 Hz to approximately 100 Hz
This closely matches the behavior of natural Slowly Adapting Type II sensory nerves found in human skin.
Instead of changing the voltage strength, the system changes the pulse frequency, exactly like biological nerves do.
This makes communication with future biological systems much more natural.
Why This Is a Major Breakthrough
Earlier artificial nerve systems often required many separate manufacturing steps.
Researchers had to manually connect pressure sensors, oscillators, electronic circuits, and flexible materials.
This process was:
Time-consuming
Difficult to reproduce
Expensive
Hard to scale
The new hybrid 3D-printing approach simplifies fabrication by integrating multiple functions into a single manufacturing process.
This improves:
Manufacturing speed
Reliability
Design flexibility
Cost efficiency
Rapid prototyping
As a result, researchers can quickly develop new artificial sensory devices without redesigning every component from scratch.
Future Applications
The possibilities for this technology are enormous.
Smarter Prosthetic Limbs
Future prosthetic hands and legs could detect stretching, movement, and touch much like natural limbs. This would give users more precise control and a more realistic sense of body position.
Soft Robotics
Soft robots are increasingly used in healthcare, manufacturing, and exploration.
Artificial sensory nerves could help these robots detect movement, safely interact with humans, and perform delicate tasks.
Wearable Medical Devices
Flexible sensors embedded into clothing or wearable patches could continuously monitor body movements for rehabilitation, sports training, or physical therapy.
Human-Machine Interfaces
Future electronic devices may communicate directly with biological nerves, enabling more natural control of computers, robots, and assistive technologies.
Even More Sensors Could Be Added
One of the greatest strengths of this 3D-printing technique is its flexibility.
Although the current system focuses on stretch sensing, researchers believe the same manufacturing process could easily include additional sensors capable of detecting:
Pressure
Temperature
Humidity
Multiple touch sensations
By changing the printed structures or sensor materials, future devices could combine several different sensing abilities into one artificial skin.
This would create highly advanced multimodal sensory systems similar to real human skin.
Looking Ahead
The researchers also believe manufacturing can become even faster in the future.
New techniques such as:
UV curing
Reactive printing
In-situ material curing
could automate even more of the production process while reducing post-processing steps.
This would make artificial sensory systems cheaper, easier to manufacture, and more widely available.
Conclusion
The development of this 3D-printed artificial afferent nerve marks an exciting milestone in neuromorphic engineering. By combining hybrid 3D printing, a highly stretchable quantum tunneling sensor, and bio-inspired electrical signaling, researchers have successfully recreated one of the human body's most important sensory functions.
Although the technology is still in the research stage, it opens the door to prosthetic limbs that feel more natural, intelligent robots that better understand their surroundings, and wearable medical devices capable of communicating with the human nervous system. As fabrication techniques continue to improve, artificial nerves like these could become a key building block in the next generation of robotics, biomedical engineering, and human-machine interaction.
Reference: Lee, M., Sotzing, M., Wang, J. et al. Hybrid 3D printing of bio-inspired artificial slowly adapting type II afferents. Nat Commun 16, 8513 (2025). https://doi.org/10.1038/s41467-025-63470-7
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