Animation: The Black Hole Collision That Created Today’s Gravitational Wave Announcement

Einstein was right. A hundred years ago, he predicted that really big objects in space can create ripples in the fabric of space-time. Today, scientists announced that these gravitational waves have been detected directly for the first time.

The confirmation came from the Laser Interferometer Gravitational-Wave Observatory (LIGO), based in Louisiana and Washington State.

The signal announced today came from the collision of two black holes. As Popular Science‘s Sophie Bushwick explains, the two black holes twirled around one another as they approached each other. The closer they got, the faster they spun, until they finally merged together into one giant black hole. The violent union released gravitational waves that LIGO detected as a “chirp” signal.

Below, this animation from Sketchfab user moroplogo explains what the black hole collision, and resulting gravity waves, may have looked like. Click around for a closer view.

Stretchy Artificial Skin Lets Prosthetic Hand Sense Heat, Humidity, and Pressure It’s so sophisticated, it can even tell the difference between a dry and soggy diaper

Prosthetic limbs that can be controlled by an amputee’s thoughts or muscle movements already exist. But what if they could also sense the environment and then send that information back to the amputee’s nervous system?

 

In order to create prosthetics that can function more like real body parts, scientists are designing artificial skins that pick up on tactile information. So far, these skins have gotten very good at sensing pressure—in fact, a skin designed by Stanford engineers is 1,000 times more sensitive than human skin. Another is self-healing.

But a new skin built by researchers in South Korea may be the smartest artificial skin yet. It’s stretchy, like real skin, and it can sense pressure, temperature, and humidity. It even has a built-in heater so it feels like living tissue. The researchers tested the artificial skin on a prosthetic hand, and they hope that some day, it will interface with a patient’s nerves so amputees can feel everything the fake skin feels.

“For prosthetic devices and artificial skin to feel natural, their temperature profile must be controlled to match that of the human body.”

“The prosthetic hand and laminated electronic skin could encounter many complex operations such as hand shaking, keyboard tapping, ball grasping, holding a cup of hot or cold drink, touching dry or wet surfaces and human to human contact,” they write in the paper, which was published today in Nature Comunnication

The bulk of the new skin is composed of a flexible, transparent silicone material called polydimethylsiloxane — or PDMS. Embedded within it are silicon nanoribbons that generate electricity when they’re squished or stretched, providing a source of tactile feedback. They can also sense whether an object is hot or cold.

The humidity sensors are made up of capacitors. When the polymer surrounding a capacitor absorbs water, the moisture changes the polymer’s ability to store a charge. The capacitors measure that storage change and use it to determine the moisture levels of the environment.

The researchers tested the humidity sensors in a somewhat unconventional way. First, they compared the artificial skin’s humidity readings to the measurements of a commercial humidity sensor, and the results matched up pretty well. That’s normal protocol. But just to be extra scientifically rigorous, the researchers had the prosthetic hand prod various diapers, and it turned out it was able to distinguish between wet and dry diapers. Success!

Next came the heating element.

“For prosthetic devices and artificial skin to feel natural, their temperature profile must be controlled to match that of the human body,” the authors write. Thermal actuators control how much heat the artificial skin emits. And although there are very simple ways to measure whether or not the skin maintains a steady 98 degrees Fahrenheit, the researchers preferred to place the hand on a plastic baby doll (hopefully it was washed after touching those soggy diapers) and then measured the amount of heat the hand transferred to the doll. It was within the normal human range.

Zhenan Bao, an artificial skin engineer at Stanford, who was not involved in the new paper, called the work exciting. She said that although the authors have created artificial skins with temperature, pressure, and humidity sensors before, integrating it with the stretchy substrate is novel.

By adjusting the shape of the silicon nanoribbon patterns, the researchers can adjust how stretchy the skin is. For regions where the skin doesn’t need to stretch, such as the fingertips, the nanoribbons are packed in a tight linear pattern to maximize sensitivity. For areas like the wrist, which need more flexibility, the nanoribbons form a more loopy pattern, allowing for more room to expand by up to 16 percent.

“This is an important demonstration of the applications of stretchable electronics,” said Bao.

The team is still working out the best way to get the sensory information from the artificial skin to the brain of the amputee. They did manage to transfer pressure information from the skin into the brain of a rat, but the paper cautions that the method may not be safe to use in people.

At the very least, perhaps this invention will fulfill every parent’s dream: Diaper-changing robots.

This Device Reads Your Mind Through Your Veins

In recent years, scientists have been developing new and creative ways to put electronics in the brain. These devices are useful for paralyzed patients to control prosthetic limbs with their minds, to help locked-in patients communicate with the outside world, or to help researchers better predict seizures in epileptic patients. But implanting them requires opening the skull, an intrusive procedure. Now researchers from the University of Melbourne have created a device that can be inserted into the brain through the blood vessels, no invasive surgery required. The study was published this week in Nature Biotechnology.

The device, about an inch long, looks similar to a stent, an apparatus placed around the heart to open up clogged blood vessels—in fact, the researchers named it a “stentrode.” To insert it, the researchers put a catheter into a vein in the neck, then snake it through the blood vessels into the head until the end is in the desired part of the brain, next to the motor cortex. Once the catheter reaches the right spot, the stentrode sticks to the sides of the blood vessel, where it can collect data from the activity of neurons nearby. The data reaches the researchers’ computers through a wire that comes out of the neck.

When the researchers tested the device on sheep, they found that the stentrodes were sensitive and transmitted good data. They also stayed in the sheep for 190 days without issue, indicating to the researchers that the devices could stay in humans for a long time without issue.

The stentrode, and similar devices that can be implanted in the brain without opening the skull, might even be useful beyond a medical capacity, becoming commonplace and changing the way we interact with computers. Of course, the necessity of a wire coming out of a user’s neck is less than ideal, so these devices might first have to become wireless if they’re going to become widespread among the population.

The researchers hope to test the stentrode in humans next year.

Scientists Create Artificial Tissues With A Cotton Candy Machine

Cotton candy artificial tissue

A research assistant creates artificial tissues using a commercial cotton candy machine.

What do cotton candy and artificial tissues have in common? They are both made of layers of thin, fibrous material. And now they can both be made with a $40 cotton candy machine, according to Vanderbilt News and reported today by Fast Company. The researchers published their proof-of-concept study last week in the journal Advanced Healthcare Materials.

The researchers were making hydrogels, a matrix of gelatinous fibers that can support living cells and replace any number of tissues in the body, especially muscle tissue like those in the heart. Hydrogels are about as close as researchers can currently get to emulating human tissues because the moist fibers that make up the hydrogel allow oxygen and nutrients to flow to and from the living cells. To create these gels, researchers spin polymer fibers together into a mass using a process called electrospinning. However the process of making viable hydrogels would often take weeks and the water-soluble gel material frequently would not dry or cool properly.

Researchers at Vanderbilt University wanted to see if electrospinning using a cotton candy machine would work as well as the traditional processes. After fiddling with the contents and concentration of the polymer solution, the researchers figured out that they could sprinkle in the human cells and an enzyme called transglutaminase–colloquially called “meat glue” in the food industry–to make the gel coalesce. The resulting material looks a lot like cotton candy, as you might imagine, but it’s a mass of living cells connected by fibers about the same size as a human capillary. Once the mass had cooled, the researchers pumped it full of oxygen and other nutrients the cells needed to survive. After a week, 90 percent of the cells were still alive, compared to the typical 60-70 percent in solid synthetic tissue that doesn’t have the fibers.

This is the latest in scientists’ recent efforts to create low-cost artificial organs—3D printing is the other popular method. But since the distribution of polymer fibers is more complex in the cotton candy hydrogel, this might be the most life-like technique to date.

In future studies the researchers hope to test their cotton candy technique with other types of cells to create tissues similar to those found in several different organs in the body.