Scientists design artificial pain receptor that senses pain intensity and self-heals

Biological and artificial nociceptive nerves with the capability of pain rating. Credit: Advanced Functional Materials, 2025. DOI: https://doi.org/10.1002/adfm.202528900

All over the body are tiny sensors called nociceptors whose job is to spot potentially harmful stimuli and send warning signals to the brain and spinal cord, helping protect us from injury or tissue damage.

In a recent study, scientists from Northeast Normal University, China, designed a jelly-like artificial nociceptive nerve pathway built using a memristor—a tiny electronic component that controls current flow and retains the memory of how much electricity has flowed through it.

The quantized conductance (QC) phenomenon in memristors, where electricity flows through a material in discrete steps rather than a smooth stream, allowed the pain receptor to go beyond simply turning on and off in response to a stimulus. Instead, it exhibited four distinct levels that correspond to the human pain scale: no pain, mild, moderate, and severe.

The bio-inspired receptor also demonstrated self-healing capabilities, including the ability to repair physical damage and mitigate fading of pain signals.

The researchers are hopeful that by mimicking how pain is sensed, artificial nociceptive systems can push the boundaries of neuroprosthetics and intuitive human–machine interaction.

Their findings are published in Advanced Functional Materials.

Bio-electronic hybrid sensorimotor nerve system for muscle contraction feedback. Credit: Advanced Functional Materials, 2025. DOI: https://doi.org/10.1002/adfm.202528900

Gel that senses pain at different levels

Artificial nociceptors have long been a focus of research and development. One of the earliest attempts to create artificial pain sensors used traditional semiconductor technology. However, researchers found that using this required extremely complicated and bulky circuits to mimic even basic human pain responses.

The advent of memristors quickly shifted the focus of scientists from trying to use semiconductors for brain-inspired computing to these tiny electronic devices with just two terminals. By leveraging their specific switching behavior, researchers have developed an artificial pain sensor that responds more strongly to repeated stimuli, without adapting to the pain stimulus over time, as biological pain sensors do.

However, existing artificial nociceptors cannot often grade pain intensity and self-heal, both of which are crucial for realistic pain perception and recovery.

The researchers in this study achieved a more precise sensing response by using two gelatin film types: 10 wt.% for pressure sensors and 1 wt.% for memristors. They then connected these two components in series to create an artificial nerve.

The team tested the pain-sensing system’s ability to distinguish intensities by applying mechanical forces ranging from 9 to 45 kPa. They detected four distinct states, ranging from no pain to severe pain.

The researchers introduced cuts up to 50.7 µm wide into the gelatin sensors and applied heat at 60 °C for 20 minutes to assess the material’s recovery and its ability to restore electrical conduction. The cuts disappeared after the heat treatment, and the electrical properties reverted to their initial state.

The artificial pain sensor was connected to the sciatic nerve of an anesthetized mouse. When the sensor was pressed, it sent electrical signals that caused the mouse’s muscles to contract, mimicking a natural avoidance response.

These results suggest that new jelly-like materials that mimic pain receptors could reshape human–machine interfaces and help develop technologies for the effective rehabilitation of people after injury.

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