Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New array measures vibrations across skin may help engineers design tactile displays

14.06.2013
In the near future, a buzz in your belt or a pulse from your jacket may give you instructions on how to navigate your surroundings.

Think of it as tactile Morse code: vibrations from a wearable, GPS-linked device that tell you to turn right or left, or stop, depending on the pattern of pulses you feel. Such a device could free drivers from having to look at maps, and could also serve as a tactile guide for the visually and hearing impaired.

Lynette Jones, a senior research scientist in MIT's Department of Mechanical Engineering, designs wearable tactile displays. Through her work, she's observed that the skin is a sensitive — though largely untapped — medium for communication.

"If you compare the skin to the retina, you have about the same number of sensory receptors, you just have them over almost two square meters of space, unlike the eye where it's all concentrated in an extremely small area," Jones says. "The skin is generally as useful as a very acute area. It's just that you need to disperse the information that you're presenting."

Knowing just how to disperse tactile information across the skin is tricky. For instance, people may be much more sensitive to stimuli on areas like the hand, as opposed to the forearm, and may respond best to certain patterns of vibrations. Such information on skin responsiveness could help designers determine the best configuration of motors in a display, given where on the skin a device would be worn.

Now Jones has built an array that precisely tracks a motor's vibrations through skin in three dimensions. The array consists of eight miniature accelerometers and a single pancake motor — a type of vibrating motor used in cellphones. She used the array to measure motor vibrations in three locations: the palm of the hand, the forearm and the thigh. From her studies with eight healthy participants, Jones found that a motor's mechanical vibrations through skin drop off quickly in all three locations, within 8 millimeters from where the vibrations originated.

Jones also gauged participants' perception of vibrations, fitting them with a 3-by-3 array of pancake motors in these three locations on the body. While skin generally stopped vibrating 8 millimeters from the source, most people continued to perceive the vibrations as far away as 24 millimeters.

When participants were asked to identify specific locations of motors within the array, they were much more sensitive on the palm than on the forearm or thigh. But in all three locations, people were better at picking out vibrations in the four corners of the array, versus the inner motors, leading Jones to posit that perhaps people use the edges of their limbs to localize vibrations and other stimuli.

"For a lot of sensory modalities, you have to work out what it is people can process, as one of the dictates for how you design," says Jones, whose results will appear in the journal IEEE Transactions on Haptics. "There's no point in making things much more compact, which may be a desirable feature from an engineering point of view, but from a human-use point of view, doesn't make a difference."

Mapping good vibrations

In addition to measuring skin's sensitivity to vibrations, Jones and co-author Katherine Sofia '12 found that skin has a strong effect on motor vibrations. The researchers compared a pancake motor's frequency of vibrations when mounted on a rigid structure or on more compliant skin. They found that in general, skin reduced a motor's vibrations by 28 percent, with the forearm and thigh having a slightly stronger dampening effect than the palm of the hand.

The skin's damping of motor vibrations is significant, Jones says, if engineers plan to build tactile displays that incorporate different frequencies of vibrations. For instance, the difference between two motors — one slightly faster than the other — may be indistinguishable in certain parts of the skin. Likewise, two motors spaced a certain distance apart may be differentiable in one area but not another.

"Should I have eight motors, or is four enough that 90 percent of the time, I'll know that when this one's on, it's this one and not that one?" Jones says. "We're answering those sorts of questions in the context of what information you want to present using a device."

Creating a buzz

Jones sees promising applications for wearable tactile displays. In addition to helping drivers navigate, she says tactile stimuli may direct firefighters through burning buildings, or emergency workers through disaster sites. In more mundane scenarios, she says tactile displays may help joggers traverse an unfamiliar city, taking directions from a buzzing wristband, instead of having to look at a smartphone.

Using data from their mechanical and perceptual experiments, Jones' group is designing arrays that can be worn across the back and around the wrist, and is investigating various ways to present vibrations. For example, a row of vibrations activated sequentially from left to right may tell a driver to turn right; a single motor that buzzes with increasing frequency may be a warning to slow down.

"There's a lot of things you can do with these displays that are fairly intuitive in terms of how people respond," Jones says, "which is important because no one's going to spend hours and hours in any application, learning what a signal means."

Written by Jennifer Chu, MIT News Office

Andrew Carleen | EurekAlert!
Further information:
http://www.mit.edu

More articles from Power and Electrical Engineering:

nachricht TU Graz researchers show that enzyme function inhibits battery ageing
21.03.2017 | Technische Universität Graz

nachricht New nanofiber marks important step in next generation battery development
13.03.2017 | Georgia Institute of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>