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 Producing electricity during flight
20.09.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Solar-to-fuel system recycles CO2 to make ethanol and ethylene
19.09.2017 | DOE/Lawrence Berkeley National Laboratory

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Party discipline for jumping genes

22.09.2017 | Life Sciences

The pyrenoid is a carbon-fixing liquid droplet

22.09.2017 | Life Sciences

Comet or asteroid? Hubble discovers that a unique object is a binary

21.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>