For individuals living with spinal cord injuries, the loss of the sense of touch is one of the most profound challenges they face. Not only does it impair basic motor skills, but it also hampers the ability to perceive the environment, impacting daily life and independence. However, a groundbreaking study published in Science brings hope for a future where a more complex sense of touch—one that allows individuals to feel tactile edges, shapes, curvatures, and movements—could be restored through advanced brain stimulation. This discovery marks a major step toward developing a fully integrated, brain-controlled bionic limb that can both move and provide real-time tactile feedback.
The research paper titled “Tactile Edges and Motion via Patterned Microstimulation of the Human Somatosensory Cortex” was authored by the US-based Cortical Bionics Research Group. It lays the foundation for how brain-computer interfaces (BCIs) may evolve, offering those with spinal cord injuries a chance to not only control a bionic limb with their thoughts but also experience detailed tactile sensations through those artificial limbs. This advancement presents a profound shift in how we think about prosthetics and brain interfacing, demonstrating that artificial touch is no longer the stuff of science fiction.
Understanding the Breakthrough: Brain-Stimulation-Driven Touch Sensations
The research team made a monumental breakthrough by decoding natural touch sensations through unique brain stimulation patterns. This allows for the sensation of touch to be translated to the brain via brain-implanted electrodes. Traditionally, one of the key limitations of prosthetic limbs is the lack of sensory feedback. Without the ability to “feel,” users often struggle to manipulate objects or perform fine motor tasks. What’s different about this study is that it integrates both the control of a bionic limb and sensory feedback, providing a user with a significantly more natural experience.
Lead author Giacomo Valle, an Assistant Professor at Chalmers University of Technology in Sweden, describes this work as being “beyond anything that has been done before in the field of BCIs.” Valle explains, “We conveyed tactile sensations related to orientation, curvature, motion and 3D shapes for a participant using a brain-controlled bionic limb. We are in another level of artificial touch now.” His team’s work is a step closer to enabling patients with spinal cord injuries to engage in activities that require a degree of dexterity, feel objects with their fingers, and perform tasks with more sophistication and a greater sense of environmental context.
The Critical Importance of Touch
The sense of touch is integral to human interaction with the world. It provides us with immediate feedback when manipulating objects and helps us determine the texture, weight, shape, and movement of those objects. It is so deeply embedded in our sensory experiences that its loss, particularly for people with spinal cord injuries, can result in a diminished quality of life. For those affected by spinal cord injuries, touch signals that would normally travel from the hand to the brain are blocked. Consequently, the sensation of grasping, holding, or manipulating objects is lost, making basic tasks like picking up a glass or a phone nearly impossible.
Previous bionic limbs, while groundbreaking in their ability to be controlled by the user’s brain, lacked this essential tactile feedback. Bionic hands, no matter how advanced, could not fully replace the functional role of the human hand without the accompanying sense of touch. In these devices, although the individual might control hand movements through brain signals, they could not feel anything in return, which made tasks like lifting, holding, or manipulating objects impractical and laborious.
The new study offers a glimpse of a solution. By creating a better connection between a brain-controlled bionic arm and the brain’s somatosensory cortex, the researchers can simulate complex touch sensations that replicate the experience of holding or moving objects. This artificial “sense of touch” makes the bionic limb feel like a natural extension of the body, giving individuals with spinal cord injuries not only more independence but also more control over their environment. In essence, the bionic limb doesn’t just work for them—it “feels” like it does.
Pioneering a New Type of Bionic Technology
The study involved two participants who had chronic brain implants in the sensory and motor regions of their brains responsible for the hand and arm. These implants enabled the researchers to decode and understand the electrical patterns emitted by the participants’ brains, even though spinal cord injuries blocked those signals from traveling to the hands.
Over several years, the researchers worked meticulously to analyze the brain’s electrical activity associated with motor intention—the intention to move a limb. These decoded patterns were then translated into commands that allowed the participants to directly control a bionic arm and hand.
But the control of the arm was only part of the breakthrough. The researchers then moved to a more advanced challenge: creating a way to transmit tactile sensations through the BCI interface. The concept of artificial touch required implanting technology that could create microstimulation in the somatosensory cortex—an area of the brain that processes sensory information like pressure, pain, and temperature. Using tiny electrodes, the team was able to “type” different sensory feedback patterns directly into the brain—similar to a specialized language of electrical impulses that encode the experience of touch.
Valle emphasizes the significance of the research: “We found a way to type these ‘tactile messages’ via microstimulation using the tiny electrodes in the brain and we found a unique way to encode complex sensations.” He continues: “This allowed for more vivid sensory feedback and experience while using a bionic hand.”
Real-World Application: Feeling the Edges and Motion of Objects
What makes the breakthrough particularly impressive is the variety of tactile experiences that were successfully transmitted to the users. Participants were able to feel the edge of an object as if it were physically touching them. They could also perceive the direction of motion along their fingertips. This allowed the researchers to simulate a 3D tactile environment within the brain that was rich and dimensional—features that were previously impossible with current BCI systems.
To elaborate on how the system works: When a user controls a bionic arm via their brain signals, the arm’s sensors detect when an object is in contact with the arm. Those sensors send signals back to the brain via the microstimulation patterns, and the user experiences the sensation of touch. This artificial tactile feedback enables users to better manipulate the object, as they can “feel” its surface properties like shape, roughness, and resistance.
This process allows participants to complete tasks with a higher degree of accuracy, such as picking up an object and moving it from one location to another. In previous models, individuals struggled with such tasks because of the lack of sensory feedback; they would not know if they were gripping an object too tightly or too loosely. By restoring complex touch feedback, this new BCI technology promises to make tasks that rely on dexterity not only possible but much easier to accomplish.
Future Directions: The Need for More Advanced Sensory Technology
While this research is an impressive first step, there is still much to be done before the technology becomes widely accessible or practical for all people with spinal cord injuries. There are multiple barriers to overcome, including the need for more complex sensors and advanced bionic technologies such as prosthetic skin, which would provide an even broader range of sensations. This kind of prosthetic technology—likely a soft, highly flexible material with integrated sensors—could allow for more dynamic interactions with the environment, like feeling warmth or texture.
Additionally, further development of implantable technology will be essential to capture a full repertoire of tactile sensations. As the study shows, the technology works remarkably well for some sensations but requires further refinement to accurately reproduce the full spectrum of touch experienced by non-impaired individuals.
Moreover, one challenge with developing tactile sensations through BCI implants lies in the fact that everyone’s brain is unique. Customizing sensory feedback that can be encoded and decoded from each user’s specific brain patterns presents a significant hurdle, but the research team is optimistic that advancements in personalized medicine and neurotechnology will make this a reality.
Conclusion: A New Horizon in Bionic Limb Technology
As the study demonstrates, artificial touch for individuals with spinal cord injuries is no longer an abstract idea, but an achievable goal. Through microstimulation of the brain’s somatosensory cortex and decoding complex motor intentions, the research team has brought us closer than ever to merging brain control with real-time tactile feedback.
By moving beyond the limitations of traditional prosthetics, this technology could drastically improve the lives of individuals living with paralysis by restoring their ability to feel objects, manipulate them with dexterity, and more fully interact with the world around them. While it’s just the beginning, the implications of this work are profound. In time, we may witness a new era in which paralyzed individuals no longer just use prosthetic limbs—they experience and feel them in ways that are eerily close to natural.
Reference: Giacomo Valle, Tactile edges and motion via patterned microstimulation of the human somatosensory cortex, Science (2025). DOI: 10.1126/science.adq5978. www.science.org/doi/10.1126/science.adq5978