Tag Archives: MIT

Preserving IoT Battery Life

At MIT, researchers have built a wake-up receiver for IoT devices. The receiver uses terahertz waves to communicate, making the chip more than ten times smaller than contemporary devices. The receiver also includes authentication that helps protect it from certain types of attacks. The low power consumption of the chip means it can help preserve battery life in robots or tiny sensors.

The current trend is towards developing ever-smaller devices for IoT or the Internet of Things. For instance, sensors can be smaller than a fingertip, capable of making any object trackable. Most of these tiny sensors, however, have even tinier batteries that are nearly impossible to replace. Therefore, engineers need to incorporate a wake-up device in these sensors. It keeps the device in a low-power sleep mode when not operating, thereby preserving battery life. The new device from MIT is capable of protecting the device from certain attacks that could drain its battery rather quickly.

The present generation of wake-up receivers is typical of the centimeter scale. This is because their antennas need to be proportional to the length of the radio waves they use for communicating. On the other hand, the MIT team utilized the terahertz wave for the receiver. As these waves are about one-tenth the length of regular radio waves, they could design the chip to be barely greater than a square millimeter.

It is possible to incorporate the wake-up receiver into microbots for monitoring environmental changes in locations that are either hazardous or too small for other robots to reach. As the device operates on terahertz frequencies, it is possible to use them in emerging applications like radio networks that operate as field-deployable swarms for collecting localized data.

Using terahertz frequencies, the researchers could make antennas the size of a few hundred micrometers on either side. The implication of such small-size antennas is that it is possible to integrate them on the chip, thereby creating a totally integrated solution. Ultimately, the researchers could build a wake-up receiver tiny enough to attach to tiny radios or sensors.

On the electromagnetic spectrum, terahertz waves exist between infrared light and microwaves. At very high frequencies, they travel much quicker than radio waves can. Terahertz waves, also known as pencil beams, travel in a rather direct path as compared to other signals, making them more secure.

However, terahertz receivers often multiply their signal by another signal so that they can alter their frequency. This process is termed frequency mixing or modulation, and it consumes a huge amount of power. The researchers at MIT used a pair of tiny transistors as antennas for detecting terahertz waves. This method of detecting consumes very little power, as it does not involve frequency mixing.

Even when they placed both antennas on the chip, the MIT wake-up chip was only 1.54 square millimeters and used only 3 microwatts to operate. The presence of two antennas maximizes its performance and makes it more sensitive to receiving signals. Once it detects the terahertz signal, it converts the analog signal into digital data for processing. The received signal contains a token, which, if it matches the wake-up receiver’s token, will activate the device.

3D Printers: Change the Shape of Your 3D-Printed Objects

When you print 3D objects on your 3D printers, they remain stable. Other than deteriorating over time, the objects do not change by themselves. However, that may be changing now. Scientists at MIT have created a new technique of printing 3-D objects where you can change the polymers in the object after printing. That means change the color of the object, grow or shrink it, or even change its shape entirely.

Associate Professor of Chemistry at MIT, Jeremiah Johnson led the research, along with Postdoc Mao Chen, and graduate student Yuwei Gu. They have written a paper on the findings, and they call the technique living polymerization. According to the team, the process creates materials whose growth can be stopped and started at will.

As they explain, after printing the material, it is possible to morph it into something else using light, even growing the material further. For instance, the team used a 3-D printed object immersed inside a solution. When they shined Ultra Violet light on the object, while it was still immersed, the resulting chemical reaction released free radicals. The free radicals bound themselves to other monomers within the solution and added them to the original object. According to the team, the process was highly reactive, and damaged the object.

At another study at the Wyss Institute for Biologically inspired Engineering of Harvard University, Dr. Jennifer Lewis is a senior author on a study on shape-shifting objects created using a 3-D printer. The team has devised a technique that allows printed objects to change their shape according to the environment.

According to the researchers at Wyss Institute, the printer creates a structure that can shift its shape. For instance, when immersed in water, the structure folds into complex and beautiful designs. The researchers claim they can adapt the process so that the printed object can fold into prescribed shapes when cooled, heated, or injected with an electrical current.

The researchers are of the opinion the technology could pave the way for generating new types of medical implants. Folding into shape when inserted into the body, such implants could generate a new family of soft electronics. According to Dr. Lewis, this is an elegant advance in the assembly of programmable materials, which a multidisciplinary approach made it possible to achieve. This has taken them farther than merely integrating form and function for creating transformable architectures.

The researchers have published their work in the journal Nature Materials. They say they were inspired by the manner in which plants grow and change their shape over time, as plants and flowers contain microscopic structures as tissues allowing them to change their shape as their environment changes. For instance, depending on temperature and humidity, plant leaves, flowers, and tendrils open or fold up.

Dr. Lewis used a printable hydrogel as it swells when added to water. The team designed specific structures under control that would change shape when placed in water. They derived the hydrogel ink from wood, and the ink had cellulose fibrils very much like the structures in plants that allow them to change shape.