Fingertip device enables realistic touch for a wide range of applications

A fingertip device that closely mimics the sensation of interacting with real objects, developed by a team led by UCL researchers, paves the way for applications in diagnosing loss of touch, video calls, robotic surgery and hazardous waste handling.

The study, published in Nature Communications, describes the development of the new touch-related technology, which enables the delivery of realistic feedback in the human fingertip to simulate touch more naturally than previous devices.

The more lifelike design of the technology means it will help to better understand the complexities of our sense of touch, with a wide range of applications already being considered.

One potential application of the technology is improving the diagnosis of patients experiencing loss of touch. Currently, this is diagnosed by a clinician touching the skin with single-fiber brushes of increasing weight and asking the patient if they can feel it, giving an indication where loss of sensation is located and how acute it is.

The bioinspired haptic (BAMH) system could be used to automate this process, speeding it up, freeing up clinicians’ time and providing more empirical data on which to base diagnoses.

Professor Helge Wurdemann, an author of the study from UCL Mechanical Engineering, said, “The BAMH system enhances our ability to quantify both the sensitivity—the minimum stimulus intensity required for humans to perceive a touch—and the differentiation of stimuli in human fingers. By reducing the subjectivity of current diagnosis methods, we think the system can significantly improve this process.”

The team have ethical approval to conduct a clinical trial to test this application, which is currently being set up. Another potential application of the technology is to improve robotic surgery techniques.

Dr. Sara Abad, an author of the study from UCL Mechanical Engineering, said, “Surgeons can feel the difference between cancerous tissue and normal tissue with their hands, for example, which helps them to define the margins of a tumor before they remove it. But if they are performing an operation using robotic arms, either in the room or remotely, this tactile ability is lost.

“We think the BAMH system can give some of that sensation back, and we’re hoping to conduct clinical trials to test this theory in the near future.”

The complexity of human touch perception has long been a barrier to the development of effective touch-related devices, often resulting in systems that struggle to deliver intuitive and realistic feedback. The BAMH system, inspired by the way human perception functions, addresses these challenges by stimulating the four primary types of touch receptors in human skin.

Professor Wurdemann said, “The human sense of touch involves sensations captured by four types of receptor, which are present in different proportions in different areas of the fingertip. Some are better at detecting edges, for example, while others are better at interpreting texture. When we touch objects, we’re receiving a complex mix of stimuli that help us to perceive them accurately.

“The system we’ve developed can produce both static and pulsing stimuli at various points on the fingertip, with intensity levels that can fall below or exceed the human sensitivity threshold. Importantly, these stimuli are delivered within a frequency range that matches the sensitivity of the touch skin receptors, allowing for a touch experience that closely emulates the sensation of interacting with real objects in everyday life.”

The pulses delivered by the BAHM system lie within the 0–130 Hertz sensitivity range of the skin’s touch receptors. This allows for more precise activation of touch receptors across the front, bottom, and lateral areas of the finger, resulting in a more accurate and selective sensation.

The study also found that sensitivity of stimuli in human fingers varies across different areas of the fingertip and across different frequencies, highlighting the importance of delivering the correct type of stimulus to each area of the finger to achieve a more realistic and accurate experience.

Dr. Abad said, “Existing touch feedback systems often require users to undergo training so that they are able to correctly interpret the stimuli they are experiencing, partly because the range of sensations the existing systems can deliver are limited and also because of the rigidity of these systems. This challenge led us to ask: how can we stimulate the skin in a way that can enable a more natural touch feedback, thereby reducing the need for extensive user training?

“To address this, we adopted a bioinspired approach, focusing on how our perception of features such as object edges, textures, and skin stretch relies heavily on the four main types of receptors within our skin. The resulting technology offers a way of incorporating touch into our virtual social interactions and can also act as a diagnostic tool for touch perception for patients who experience sensitivity loss.”

On Saturday 14 September, Professor Wurdemann and Dr. Abad Guaman will present their innovative at the British Science Festival hosted at the University of East London. Attendees at the Festival will have the opportunity to feel, first-hand, how this technology simulates real-world sensations on their forearms, showing how digital and real-life connections can come closer together.