Can you feel me now?

New array measures vibrations across the skin, may help engineers design optimal, wearable tactile displays.

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.”

Roberta Klatzky, a professor of psychology at Carnegie Mellon University, says that measurements taken by Jones’ arrays can be used to set up displays in which the location of a stimulus — for example, a pattern to convey a letter — is important.

“A major challenge is to enable people to tell the difference between patterns applied to the skin as, for example, blind people do when reading Braille,” says Klatzky, who specializes in the study of spatial cognition. “Lynette’s work sets up a methodology and potential guidelines for effective pattern displays.”

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.”


Pacinian corpuscle

A Pacinian corpuscle is a type of touch receptor located in the skin. It is classed as a mechanoreceptor, meaning it is part of the group of sensory receptors that respond to touch and pressure. Pacinian corpuscles are especially suited to feeling rough surfaces and detecting vibration. They respond to transient touches rather than sustained pressure. This is because a Pacinian corpuscle is able to quickly adapt to pressure so that it no longer acts as a stimulus.

Sensory Receptors:

  • Are specialised cells that can detect changes in our surroundings
  • They are energy transducers that convert one form of energy into another
  • Each change in energy levels in the environment is called a stimulus
  • Whatever the stimulus, the sensory receptors convert the enrgy into a form of electrical energy called a nerve impulse

Types of Receptors

  • Light-sensitive cells (rods and cones in the retina of the eye) –> Detects light intensity and range of wavelengths
  • Olfactory cells (line the inner surface of the naval cavity) –> Dectect presence of volatile chemicals
  • Taste Buds (on the tongue, hard palate, epiglottis and first part of the oesophagus –> Detect presence of soluble chemicals
  • Pressure receptors known as pacinian corpuscles (skin) –> detect pressure on the skin
  • Sound receptors (in the inner ear) –> Detect vibrations in the air
  • Muscle spindles known as proprioreceptors –> Length of muscle fibres, whether arm is bent or not measured by length of muscle fibres

Tsukiuta SS 20 July 2015

Translated by hana-megane | Proof by ironclaw | Edit by mesu & mame

Part 12345

☆Irregular Fortune Telling☆
Shun: Today’s lucky one is March; January, be careful

Hajime: ouch
Haru: ? Aah, did you get a paper cut from touching the script?
Hajime: Yeah
Haru: Paper cuts are small but hurt because the fingers have a great concentration of sensory receptors and that causes jagged wound similar to one caused by saw––
Hajime: Your explanation is too long

Keep reading

Is Judo a Fix for Flat Feet?

Judo training may help to prevent flat feet and other foot deformities in children, new research suggests

Judo training may help to prevent flat feet and other foot deformities in children, says a study published online in the Journal of Pediatric Orthopaedics B. Boys who regularly practiced judo had significantly higher foot arches and better balance than a control group of relatively inactive boys, the study found.

Recent studies have shown that flat feet are common in children, especially boys who are overweight and unfit. Those conditions can alter foot position, gait and balance, the researchers said. They suggest judo may be a more appealing fitness activity for young boys than traditional gymnastic exercises to help prevent flat feet. Judo is mostly performed barefoot and on a soft surface, which stimulates sensory receptors on the bottom of the foot, they said.

Babies are born with flat feet but usually develop arches by their 6th birthday, according to the American Academy of Pediatrics.

For the study, researchers in Poland recruited 29 boys enrolled in 90-minute judo classes three times a week and 29 boys who didn’t participate in sports outside of school. Both groups were 11.5 years old, on average, and had similar body types.

The researchers assessed boys’ foot-arch height in both sitting and standing positions and measured balance with a so-called flamingo test: The boys stood on one leg for as long as possible on a strip of wood about 1 inch wide, holding the other leg bent at the knee.

Boys who practiced judo had significantly higher arches compared with nontrained boys. The best flamingo test score in the judo group was 125.1 seconds, compared with 27.3 seconds in the control group. The worst scores in the judo-trained and nontrained groups were 4.7 and 1.2 seconds, respectively.

Caveat: The study was small and didn’t include girls.

Summer swoon: Older people taking blood-pressure medication may need lower dosages during the hot summer months to help prevent fainting, suggests a study published online in the American Journal of Medicine. The study found fainting episodes, called syncope, were significantly more common in summer than in winter among patients taking antihypertensive drugs. Nearly 75% of patients with summer syncope were age 60 or older.

Older people normally have a greater risk of syncope than younger people. Antihypertensive medications and dehydration from high summer temperatures further increase the risk, the researchers said.

Researchers at the University of Arizona in Tucson reviewed medical records of 834 patients hospitalized for syncope from 2010 to 2013. About 57% were treated between May and September, the warmest months in Tucson, and the rest from November to March. Among those on blood-pressure medications, representing just over a third of the total patients, 40.5% developed syncope during the summer months, compared with 29% in the winter.

Summer syncope was associated with dehydration and was more common in women. By contrast, more men developed syncope in winter.

Angiotensin converting enzyme, or ACE, inhibitors and angiotensin receptor blockers were the most commonly prescribed medications, followed by beta-blockers and calcium-channel blockers. The number of medications patients were taking was unrelated to syncope, the research showed.

Caveat: The study was relatively small and conducted at one hospital.

Functional fat: Cosmetic surgery to reduce excess fat in the thighs could increase the risk of cardiovascular disease, suggests a small study in the American Journal of Physiology−Endocrinology and Metabolism. The study found that triglycerides, a type of fat in the blood associated with heart health, increased significantly in women who had leg fat removed by liposuction, compared with a control group.

Previous studies have shown that carrying excess fat in the hips and thighs, as opposed to in the abdomen, is associated with a lower risk of Type 2 diabetes, heart attacks and other cardiovascular conditions. This study found that removing leg fat increased triglycerides in the blood, the researchers said. This could contribute to disease risk.

More than 300,000 women and 40,000 men in the U.S. underwent various liposuction procedures in 2014, according to the American Society for Aesthetic Plastic Surgery.

The study, at the University of Colorado in Aurora, involved 29 normal-weight women, age 45 years old on average, seeking femoral or upper-leg liposuction. Seventeen of the women had the surgery, while 12 served as controls and were offered liposuction after the study. None of the subjects had high triglycerides or conditions associated with cardiovascular disease.

Fat samples from the subjects’ thighs and abdomen were measured at the start of the study, and two and 14 months after surgery. Body-composition changes were measured with CT scans and X-rays. There was no change in triglycerides two months postsurgery. But after 14 months, triglycerides increased by 24% in the liposuction group, though levels were still in the normal range. Triglycerides didn’t change in the controls.

Leg fat remained reduced 14 months after liposuction, and there were no increases in fat elsewhere in the body to compensate for leg-fat removal, the study said.

Caveat: It isn’t known if liposuction would trigger a similar response in obese women or those with a tendency to store fat in the abdomen, researchers said. The study didn’t include men.


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Gundis or “comb rats” are small rodents. They live in the rocky deserts in northern Africa. They are social animals who live in colonies of up to a hundred or more individuals. They like to make a lot of noise.

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The Spoon-billed Sandpiper is a critically endangered small wading bird who breeds in Russia and winters in Southeast Asia.

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