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From virtual reality to rehabilitation and communication, haptic technology has revolutionized the way humans interact with the digital world. While early haptic devices focused on single-sensory cues like vibration-based notifications, modern advancements have paved the way for multisensory haptic devices that integrate various forms of touch-based feedback, including vibration, skin stretch, pressure and temperature.
 
Recently, a team of experts, including Rice University’s Marcia O’Malley and Daniel Preston, graduate student Joshua Fleck, alumni Zane Zook ’23 and Janelle Clark ’22 and other collaborators, published an in-depth review in Nature Reviews Bioengineering analyzing the current state of wearable multisensory haptic technology, outlining its challenges, advancements and real-world applications.
Haptic devices, which enable communication through touch, have evolved significantly since their introduction in the 1960s. Initially, they relied on rigid, grounded mechanisms acting as user interfaces, generating force-based feedback from virtual environments. But with advancements in sensing and actuation technology, haptic devices have become increasingly wearable. Today’s innovations focus on cutaneous feedback — stimulating the skin’s receptors to provide realistic touch sensations — rather than kinesthetic feedback, which mimics force exerted on the musculoskeletal system.
 
“Wearable haptic devices are now integrated into consumer products such as smartwatches and gaming accessories, and they are serving more complex roles in health care, robotics and immersive media,” said O’Malley, the Thomas Michael Panos Family Professor in Engineering and professor and chair of mechanical engineering. “A new shift toward multisensory haptic feedback, which means delivering more than one type of touch stimulus simultaneously, is enhancing user experience, but it presents new engineering and perceptual challenges. As this technology continues to evolve, we will see it move to a richer, multisensory experience — one that bridges the gap between digital interaction and human touch.”

Designing effective, wearable multisensory haptic devices requires a deep understanding of human touch perception, and the research team identified several key challenges in the field today. One of the most significant hurdles is the variability in skin contact mechanics as differences in skin elasticity, receptor distribution and external factors like humidity can alter how haptic stimuli are perceived. Another issue is tactile masking, where multiple haptic sensations such as vibration and skin stretch can interfere with one another, reducing perceptual clarity.

“Every person’s skin responds differently to stimuli due to variations in elasticity, moisture and even body hair,” said Preston, assistant professor of mechanical engineering. “This variability makes designing universally effective devices incredibly complex.”
In addition, wearability and comfort continue to be major considerations in every product. Haptic devices must be designed to fit different body locations without causing discomfort, restricting movement or disrupting daily activities. Factors such as weight, size and attachment methods all play a crucial role in ensuring long-term usability.

“True immersion in haptic technology depends not just on what users feel but on how naturally and comfortably they experience it,” Preston said.

In addition to highlighting challenges, the authors identified several emerging actuation methods that could redefine wearable haptic technology.

Electromechanical actuation, commonly used in vibrational feedback systems, remains the most widely adopted method due to its reliability and affordability. However, it often struggles to provide a diverse range of haptic cues. Polymeric actuation, which relies on smart polymers that change shape or texture when exposed to stimuli, offers a lightweight and flexible alternative for delivering haptic feedback. Fluidic actuation, which utilizes pressurized air or liquid to generate dynamic tactile sensations, is gaining traction in soft robotics and textile-based haptic wearables, offering new possibilities for comfort and adaptability. Additionally, thermal actuation is emerging as a way to enhance immersion in virtual environments or simulate real-world interactions through warming or cooling sensations.

“We expect these technologies to significantly expand the scope of haptic feedback, particularly in fields such as medical rehabilitation, prosthetic development and human-machine interaction,” O’Malley said. “Although promising, further refinement is needed to improve response time, durability and energy efficiency.”

The review also offers insight into how wearable haptic technology is poised to unlock new possibilities in human interaction with digital and physical environments. In virtual and augmented reality, multisensory haptics enhance immersion by allowing users to feel digital objects, improving experiences in gaming, training simulations and education. In health care and rehabilitation, wearable haptics assist in motor skill training, post-stroke rehabilitation and prosthetic limb feedback, enabling patients to interact more effectively with their surroundings. Assistive technology and communication applications leverage tactile interfaces to help individuals with vision or hearing impairments by translating auditory or visual information into touch-based signals. Navigation and guidance systems benefit from haptic wearables by providing intuitive directional cues, aiding visually impaired individuals and improving hands-free navigation in fields such as military and aviation. Additionally, teleoperation and robotics stand to gain significantly as remote-controlled robotic systems with haptic feedback allow users to “feel” objects from a distance, improving precision in delicate tasks like robotic surgery.

Despite significant progress, the authors emphasized the need for further exploration in multisensory haptic perception. Understanding how the brain processes simultaneous haptic cues will be crucial in refining future devices, and ensuring widespread adoption will require a balance between technological sophistication, user comfort and practical usability.

“The ultimate goal is to create haptic devices that feel as natural as real-world touch,” O’Malley said.

Lincoln Laboratory and MIT researchers are creating new types of bioabsorbable fabrics that mimic the unique way soft tissues stretch while nurturing growing cells.

Treating severe or chronic injury to soft tissues such as skin and muscle is a challenge in health care. Current treatment methods can be costly and ineffective, and the frequency of chronic wounds in general from conditions such as diabetes and vascular disease, as well as an increasingly aging population, is only expected to rise.

One promising treatment method involves implanting biocompatible materials seeded with living cells (i.e., microtissue) into the wound. The materials provide a scaffolding for stem cells, or other precursor cells, to grow into the wounded tissue and aid in repair. However, current techniques to construct these scaffolding materials suffer a recurring setback. Human tissue moves and flexes in a unique way that traditional soft materials struggle to replicate, and if the scaffolds stretch, they can also stretch the embedded cells, often causing those cells to die. The dead cells hinder the healing process and can also trigger an inadvertent immune response in the body.

"The human body has this hierarchical structure that actually un-crimps or unfolds, rather than stretches," says Steve Gillmer, a researcher in MIT Lincoln Laboratory's Mechanical Engineering Group. "That's why if you stretch your own skin or muscles, your cells aren't dying. What's actually happening is your tissues are uncrimping a little bit before they stretch."

Gillmer is part of a multidisciplinary research team that is searching for a solution to this stretching setback. He is working with Professor Ming Guo from MIT's Department of Mechanical Engineering and the laboratory's Defense Fabric Discovery Center (DFDC) to knit new kinds of fabrics that can uncrimp and move just as human tissue does.
The idea for the collaboration came while Gillmer and Guo were teaching a course at MIT. Guo had been researching how to grow stem cells on new forms of materials that could mimic the uncrimping of natural tissue. He chose electrospun nanofibers, which worked well, but were difficult to fabricate at long lengths, preventing him from integrating the fibers into larger knit structures for larger-scale tissue repair.

"Steve mentioned that Lincoln Laboratory had access to industrial knitting machines," Guo says. These machines allowed him to switch focus to designing larger knits, rather than individual yarns. "We immediately started to test new ideas through internal support from the laboratory."

Gillmer and Guo worked with the DFDC to discover which knit patterns could move similarly to different types of soft tissue. They started with three basic knit constructions called interlock, rib, and jersey.

"For jersey, think of your T-shirt. When you stretch your shirt, the yarn loops are doing the stretching," says Emily Holtzman, a textile specialist at the DFDC. "The longer the loop length, the more stretch your fabric can accommodate. For ribbed, think of the cuff on your sweater. This fabric construction has a global stretch that allows the fabric to unfold like an accordion."

Interlock is similar to ribbed but is knitted in a denser pattern and contains twice as much yarn per inch of fabric. By having more yarn, there is more surface area on which to embed the cells. "Knit fabrics can also be designed to have specific porosities, or hydraulic permeability, created by the loops of the fabric and yarn sizes," says Erin Doran, another textile specialist on the team. "These pores can help with the healing process as well."

So far, the team has conducted a number of tests embedding mouse embryonic fibroblast cells and mesenchymal stem cells within the different knit patterns and seeing how they behave when the patterns are stretched. Each pattern had variations that affected how much the fabric could uncrimp, in addition to how stiff it became after it started stretching. All showed a high rate of cell survival, and in 2024 the team received an R&D 100 award for their knit designs.

Gillmer explains that although the project began with treating skin and muscle injuries in mind, their fabrics have the potential to mimic many different types of human soft tissue, such as cartilage or fat. The team recently filed a provisional patent that outlines how to create these patterns and identifies the appropriate materials that should be used to make the yarn. This information can be used as a toolbox to tune different knitted structures to match the mechanical properties of the injured tissue to which they are applied.

"This project has definitely been a learning experience for me," Gillmer says. "Each branch of this team has a unique expertise, and I think the project would be impossible without them all working together. Our collaboration as a whole enables us to expand the scope of the work to solve these larger, more complex problems."