Licker: A Soft, Lifelike Robot Tongue That Mimics Human Licking to Build Bonds Between Humans and Animals
In the world of robotics, innovation often surprises us. Robots now walk, talk, run, fly, and even cook. But have you ever imagined a robot that licks like a human tongue?
Meet Licker – a flexible tongue robot developed by Ryota Shijo and his team. This robot doesn't just copy the motion of a tongue. It also feels like a real tongue — soft, wet, and slimy — just like when a pet lovingly licks you.
This breakthrough project opens new possibilities for how robots can interact with humans and animals, not just through sight or sound, but through touch. Let’s explore this fascinating invention in detail.
What Is Licker?
Licker is a flexible robotic tongue created by a group of researchers led by Ryota Shijo. Its purpose is not just scientific curiosity. Licker is designed to create emotional and social bonding through licking, which is a common behavior among animals and even in human affection.
While licking may seem strange to focus on, it is actually a powerful form of communication in many species. Pets often lick their owners to show love and loyalty. The same can be true in animal-to-animal interactions. By recreating this natural motion and sensation, Licker aims to enhance emotional connection in new and unexpected ways.
Why Licking?
Licking might sound odd in the context of robotics, but there’s real science behind this idea.
In many species — dogs, cats, cows, and even humans — licking is a form of non-verbal communication. It can mean affection, comfort, or submission. Puppies lick their mother’s face; cats groom each other; dogs lick humans to greet them.
This simple action helps build trust and emotional bonding. By giving robots this ability, scientists hope to create more emotionally intelligent machines, especially in caregiving, therapy, or animal companionship.
Analyzing Human Tongue Motion
Before creating the robot, Ryota Shijo and his team had to understand how the human tongue moves. Tongue motion is complex — it stretches, curls, flattens, and rotates in very smooth ways.
To mimic this natural behavior, the team studied real human tongue movements and identified four basic tongue motions:
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Flat surface lick – similar to how a cat licks milk.
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Tip-focused lick – like gently touching with just the tip.
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Wide stroke lick – similar to grooming behavior.
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Rhythmic licking motion – repeated, smooth movements.
These movements are common across humans and animals and represent the core types of tongue gestures used in affectionate licking.
Based on these findings, the researchers developed a robotic tongue capable of repeating these actions realistically.
Building the Licker Robot: Mimicking Human Tongue Movements
To develop Licker, the team needed to create a robot that could perform natural and fluid tongue motions.
They designed a flexible robotic structure that can move in multiple directions. The robot’s body is soft and bendable, allowing it to twist, extend, and flex just like a real tongue. This is not a hard plastic robot — it is soft and lifelike, made of flexible materials that simulate biological texture and flexibility.
The robot includes servo motors and sensors that allow it to respond and move smoothly. It can replicate the licking motion in different speeds, patterns, and directions.
The engineering challenge was to create not just the movement, but also the feeling of being licked.
The Tactile Challenge: Softness and Slime
Licking is not only about motion — it also involves tactile sensation. To recreate this, the team carefully studied the texture and feeling of the human tongue.
They focused on two major tactile features:
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Softness of the tongue itself – The tongue is made of muscle and has a soft surface. It must feel gentle when it touches the skin.
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Slimy feeling of saliva – Licking usually involves moisture. That wet, slightly sticky feeling is a part of what makes licking feel real.
To simulate this, the team used soft silicone-based materials for the tongue surface. These materials are elastic, smooth, and safe for contact with human skin.
For the slimy effect, they used a special coating or liquid film that creates the feeling of moisture. Some prototypes even use a thin layer of gel or water-based lubricant to simulate saliva. The result is a tongue robot that feels shockingly realistic when it touches or licks the skin.
Demonstration and Results: Can Licker Truly Mimic a Real Tongue?
After building the Licker robot, the team conducted demonstrations to test its effectiveness.
Participants were asked to experience the robot licking their skin. The researchers observed whether the tactile sensation felt realistic, and whether the motion reminded them of an affectionate animal or person.
The results were impressive:
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Most participants said the licking sensation felt very real, almost like being licked by a pet.
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The soft texture and moisture made it feel lifelike.
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The natural movement patterns of the tongue were close to human or animal licking.
This confirmed that Licker could successfully mimic both the motion and the feeling of being licked — something no robot has done before at this level of realism.
Applications: Where Can Licker Be Used?
The Licker robot may sound like a novelty, but it has many practical and meaningful applications.
1. Animal Interaction Robots
Robotic animals are used in therapy and companionship, especially for the elderly or people with disabilities. By adding licking capabilities, these robots can simulate real animal affection, helping people feel comforted and less lonely.
2. Therapy and Emotional Support
Licking is calming and comforting for some people. In therapy for conditions like autism, anxiety, or trauma, a soft robot with lifelike touch might provide emotional support.
3. Human-Robot Interaction Research
Licker helps scientists explore how humans emotionally respond to tactile robots. It opens a new dimension of touch-based communication.
4. Sensory Research
The robot can help in understanding how human skin senses moisture, pressure, and texture, which is useful in developing prosthetics and touch-sensitive devices.
Ethical Questions: Is It Okay for Robots to Lick?
Like all new technologies, Licker raises ethical and social questions:
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Is it appropriate for robots to mimic intimate actions?
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Should robots imitate animal or human affection?
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Could this be misused or misunderstood?
The creators emphasize that Licker is not designed for inappropriate use. Its goal is to simulate bonding and comfort — not to cross boundaries.
In all experiments and demonstrations, the robot is used respectfully and safely, often in animal simulation or therapy settings.
As with any technology, the key is to use it responsibly and educate users about its purpose.
Future of Licker: What’s Next?
Licker is just the beginning. In the future, we could see:
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Improved versions with even more lifelike saliva simulation.
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Robots that respond to emotional cues and lick only when appropriate.
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Use of AI and sensors to decide when and how to interact.
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Integration with robot pets or therapy robots.
There’s also the possibility of using similar technology in robot tongues for taste sensing, speech therapy, or even robot chefs that can simulate taste through touch.
Conclusion: A Licking Robot with a Gentle Touch
The Licker robot may sound unusual, but it represents a bold step in human-robot interaction. By recreating the tactile emotion of licking, Ryota Shijo and his team have opened a new way for machines to connect with living beings — emotionally and physically.
From elderly care to therapy, from robotic pets to emotional support systems, Licker has the potential to change how we see robots — not just as tools or machines, but as touchable companions capable of expressing care.
In a world where loneliness is rising and emotional connection is rare, perhaps a soft robotic lick can offer comfort in ways we never imagined.
Reference: Ryota Shijo, Mizuki Nagano, Izumi Mizoguchi, Takahiro Ando, Kanji Tamura, Keigo Hiki, Sho Sakurai, Koichi Hirota, and Takuya Nojima. 2019. Licker: A Tongue Robot for Representing Realistic Tongue Motions. In SIGGRAPH Asia 2019 Emerging Technologies (SA '19). Association for Computing Machinery, New York, NY, USA, 27–28. https://doi.org/10.1145/3355049.3360533
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