Tag Archives: Lei Wei

Electrotactile rendering device virtualizes the sense of touch

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I stumbled across this November 15, 2022 news item on Nanowerk highlighting work on the sense of touch in the virual originally announced in October 2022,

A collaborative research team co-led by City University of Hong Kong (CityU) has developed a wearable tactile rendering system, which can mimic the sensation of touch with high spatial resolution and a rapid response rate. The team demonstrated its application potential in a braille display, adding the sense of touch in the metaverse for functions such as virtual reality shopping and gaming, and potentially facilitating the work of astronauts, deep-sea divers and others who need to wear thick gloves.

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Here’s what you’ll need to wear for this virtual tactile experience,

Caption: The new wearable tactile rendering system can mimic touch sensations with high spatial resolution and a rapid response rate. Credit: Robotics X Lab and City University of Hong Kong

An October 20, 2022 City University of Hong Kong (CityU) press release (also on EurekAlert), which originated the news item, delves further into the research,

“We can hear and see our families over a long distance via phones and cameras, but we still cannot feel or hug them. We are physically isolated by space and time, especially during this long-lasting pandemic,” said Dr Yang Zhengbao,Associate Professor in the Department of Mechanical Engineering of CityU, who co-led the study. “Although there has been great progress in developing sensors that digitally capture tactile features with high resolution and high sensitivity, we still lack a system that can effectively virtualize the sense of touch that can record and playback tactile sensations over space and time.”

In collaboration with Chinese tech giant Tencent’s Robotics X Laboratory, the team developed a novel electrotactile rendering system for displaying various tactile sensations with high spatial resolution and a rapid response rate. Their findings were published in the scientific journal Science Advances under the title “Super-resolution Wearable Electro-tactile Rendering System”.

Limitations in existing techniques

Existing techniques to reproduce tactile stimuli can be broadly classified into two categories: mechanical and electrical stimulation. By applying a localised mechanical force or vibration on the skin, mechanical actuators can elicit stable and continuous tactile sensations. However, they tend to be bulky, limiting the spatial resolution when integrated into a portable or wearable device. Electrotactile stimulators, in contrast, which evoke touch sensations in the skin at the location of the electrode by passing a local electric current though the skin, can be light and flexible while offering higher resolution and a faster response. But most of them rely on high voltage direct-current (DC) pulses (up to hundreds of volts) to penetrate the stratum corneum, the outermost layer of the skin, to stimulate the receptors and nerves, which poses a safety concern. Also, the tactile rendering resolution needed to be improved.

The latest electro-tactile actuator developed by the team is very thin and flexible and can be easily integrated into a finger cot. This fingertip wearable device can display different tactile sensations, such as pressure, vibration, and texture roughness in high fidelity. Instead of using DC pulses, the team developed a high-frequency alternating stimulation strategy and succeeded in lowering the operating voltage under 30 V, ensuring the tactile rendering is safe and comfortable.

They also proposed a novel super-resolution strategy that can render tactile sensation at locations between physical electrodes, instead of only at the electrode locations. This increases the spatial resolution of their stimulators by more than three times (from 25 to 105 points), so the user can feel more realistic tactile perception.

Tactile stimuli with high spatial resolution

“Our new system can elicit tactile stimuli with both high spatial resolution (76 dots/cm2), similar to the density of related receptors in the human skin, and a rapid response rate (4 kHz),” said Mr Lin Weikang, a PhD student at CityU, who made and tested the device.

The team ran different tests to show various application possibilities of this new wearable electrotactile rendering system. For example, they proposed a new Braille strategy that is much easier for people with a visual impairment to learn.

The proposed strategy breaks down the alphabet and numerical digits into individual strokes and order in the same way they are written. By wearing the new electrotactile rendering system on a fingertip, the user can recognise the alphabet presented by feeling the direction and the sequence of the strokes with the fingertip sensor. “This would be particularly useful for people who lose their eye sight later in life, allowing them to continue to read and write using the same alphabetic system they are used to, without the need to learn the whole Braille dot system,” said Dr Yang.

Enabling touch in the metaverse

Second, the new system is well suited for VR/AR [virtual reality/augmented reality] applications and games, adding the sense of touch to the metaverse. The electrodes can be made highly flexible and scalable to cover larger areas, such as the palm. The team demonstrated that a user can virtually sense the texture of clothes in a virtual fashion shop. The user also experiences an itchy sensation in the fingertips when being licked by a VR cat. When stroking a virtual cat’s fur, the user can feel a variance in the roughness as the strokes change direction and speed.

The system can also be useful in transmitting fine tactile details through thick gloves. The team successfully integrated the thin, light electrodes of the electrotactile rendering system into flexible tactile sensors on a safety glove. The tactile sensor array captures the pressure distribution on the exterior of the glove and relays the information to the user in real time through tactile stimulation. In the experiment, the user could quickly and accurately locate a tiny steel washer just 1 mm in radius and 0.44mm thick based on the tactile feedback from the glove with sensors and stimulators. This shows the system’s potential in enabling high-fidelity tactile perception, which is currently unavailable to astronauts, firefighters, deep-sea divers and others who need wear thick protective suits or gloves.

“We expect our technology to benefit a broad spectrum of applications, such as information transmission, surgical training, teleoperation, and multimedia entertainment,” added Dr Yang.

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Here’s a link to and a citation for the paper,

Super-resolution wearable electrotactile rendering system by Weikang Lin, Dongsheng Zhang, Wang Wei Lee, Xuelong Li, Ying Hong, Qiqi Pan, Ruirui Zhang, Guoxiang Peng, Hong Z. Tan, Zhengyou Zhang, Lei Wei, and Zhengbao Yang. Science Advances 9 Sep 2022 Vol 8, Issue 36 DOI: 10.1126/sciadv.abp8738

This paper is open access.

“Breaking Me Softly” at the nanoscale

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“Breaking Me Softly” sounds like a song title but in this case the phrase as been coined to describe a new technique for controlling materials at the nanoscale according to a June 6, 2016 news item on ScienceDaily,

A finding by a University of Central Florida researcher that unlocks a means of controlling materials at the nanoscale and opens the door to a new generation of manufacturing is featured online in the journal Nature.

Using a pair of pliers in each hand and gradually pulling taut a piece of glass fiber coated in plastic, associate professor Ayman Abouraddy found that something unexpected and never before documented occurred — the inner fiber fragmented in an orderly fashion.

“What we expected to see happen is NOT what happened,” he said. “While we thought the core material would snap into two large pieces, instead it broke into many equal-sized pieces.”

He referred to the technique in the Nature article title as “Breaking Me Softly.”

A June 6, 2016 University of Central Florida (UCF) news release (also on EurekAlert) by Barbara Abney, which originated the news item, expands on the theme,

The process of pulling fibers to force the realignment of the molecules that hold them together, known as cold drawing, has been the standard for mass production of flexible fibers like plastic and nylon for most of the last century.

Abouraddy and his team have shown that the process may also be applicable to multi-layered materials, a finding that could lead to the manufacturing of a new generation of materials with futuristic attributes.

“Advanced fibers are going to be pursuing the limits of anything a single material can endure today,” Abouraddy said.

For example, packaging together materials with optical and mechanical properties along with sensors that could monitor such vital sign as blood pressure and heart rate would make it possible to make clothing capable of transmitting vital data to a doctor’s office via the Internet.

The ability to control breakage in a material is critical to developing computerized processes for potential manufacturing, said Yuanli Bai, a fracture mechanics specialist in UCF’s College of Engineering and Computer Science.

Abouraddy contacted Bai, who is a co-author on the paper, about three years ago and asked him to analyze the test results on a wide variety of materials, including silicon, silk, gold and even ice.

He also contacted Robert S. Hoy, a University of South Florida physicist who specializes in the properties of materials like glass and plastic, for a better understanding of what he found.

Hoy said he had never seen the phenomena Abouraddy was describing, but that it made great sense in retrospect.

The research takes what has traditionally been a problem in materials manufacturing and turned it into an asset, Hoy said.

“Dr. Abouraddy has found a new application of necking” –  a process that occurs when cold drawing causes non-uniform strain in a material, Hoy said.  “Usually you try to prevent necking, but he exploited it to do something potentially groundbreaking.”

The necking phenomenon was discovered decades ago at DuPont and ushered in the age of textiles and garments made of synthetic fibers.

Abouraddy said that cold-drawing is what makes synthetic fibers like nylon and polyester useful. While those fibers are initially brittle, once cold-drawn, the fibers toughen up and become useful in everyday commodities. This discovery at DuPont at the end of the 1920s ushered in the age of textiles and garments made of synthetic fibers.

Only recently have fibers made of multiple materials become possible, he said.  That research will be the centerpiece of a $317 Million U.S. Department of Defense program focused on smart fibers that Abouraddy and UCF will assist with.   The Revolutionary Fibers and Textiles Manufacturing Innovation Institute (RFT-MII), led by the Massachusetts Institute of Technology, will incorporate research findings published in the Nature paper, Abouraddy said.

The implications for manufacturing of the smart materials of the future are vast.

By controlling the mechanical force used to pull the fiber and therefore controlling the breakage patterns, materials can be developed with customized properties allowing them to interact with each other and eternal forces such as the sun (for harvesting energy) and the internet in customizable ways.

A co-author on the paper, Ali P. Gordon, an associate professor in the Department of Mechanical & Aerospace Engineering and director of UCF’s Mechanics of Materials Research Group said that the finding is significant because it shows that by carefully controlling the loading condition imparted to the fiber, materials can be developed with tailored performance attributes.

“Processing-structure-property relationships need to be strategically characterized for complex material systems. By combining experiments, microscopy, and computational mechanics, the physical mechanisms of the fragmentation process were more deeply understood,” Gordon said.

Abouraddy teamed up with seven UCF scientists from the College of Optics & Photonics and the College of Engineering & Computer Science (CECS) to write the paper.   Additional authors include one researcher each from the Massachusetts Institute of Technology, Nanyang Technological University in Singapore and the University of South Florida.

Here’s a link to and a citation for the paper,

Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing by Soroush Shabahang, Guangming Tao, Joshua J. Kaufman, Yangyang Qiao, Lei Wei, Thomas Bouchenot, Ali P. Gordon, Yoel Fink, Yuanli Bai, Robert S. Hoy & Ayman F. Abouraddy. Nature (2016) doi:10.1038/nature17980 Published online  06 June 2016

This paper is behind a paywall.