Power/Performance Bits: Nov. 25

Rigid or flexible in one device
Researchers at the Korea Advanced Institute of Science and Technology (KAIST), Electronics and Telecommunications Research Institute (ETRI) in Daejeon, University of Colorado Boulder, Washington University in St. Louis, Cornell University, and Georgia Institute of Technology proposed a system that would allow electronics to transform from stiff devices to flexible wearables.

The platform, which they called ‘Transformative Electronics Systems,’ can mechanically transform its shape, flexibility, and stretchability for different applications.

“This new class of electronics will not only offer robust, convenient interfaces for use in both tabletop or handheld setups, but also allow seamless integration with the skin when applied onto our bodies,” said Jae-Woong Jeong, a professor from the School of Electrical Engineering at KAIST.

The transformative electronics consist of a special gallium metal structure, hermetically encapsulated and sealed within a soft silicone material, combined with electronics that are designed to be flexible and stretchable. The mechanical transformation of the electronic systems is specifically triggered by temperature change events controlled by the user.

A research team at KAIST says their new platform called ‘Transformative Electronics Systems’ will open a new class of electronics, allowing reconfigurable electronic interfaces to be optimized for a variety of applications. (Video source: KAIST)

“Gallium is an interesting key material. It is biocompatible, has high rigidity in solid form, and melts at a temperature comparable to the skin’s temperature,” said Sang-Hyuk Byun, a researcher at KAIST.

Once the device comes into contact with a human body, the gallium metal encapsulated inside the silicone changes to a liquid state and softens the whole electronic structure, making it stretchable, flexible, and wearable. The gallium metal then solidifies again once the structure is peeled off the skin, making the electronic circuits stiff and stable. The addition of flexible electronic circuits meant they could work when either flexible or rigid.

The researchers were able to demonstrate applications including a multi-purpose personal electronics with variable stiffness and stretchability, a pressure sensor with tuneable bandwidth and sensitivity, and a neural probe that softens upon implantation into brain tissue.

Joo Yong Sim, a researcher with ETRI, also cited the importance of interdisciplinary efforts. “We worked together with electrical, mechanical, and biomedical engineers, as well as material scientists and neuroscientists to make this breakthrough.”

Extending IoT range
Researchers at Brigham Young University, Washington University in St. Louis, and University of Utah created a protocol that extends the distance a Wi-Fi-enabled device can send and receive signals. The team says it can extend the distance at which IoT devices can be installed from a Wi-Fi access point by more than 60 meters without additional hardware.

“That’s the really cool thing about this technology: it’s all done in software,” said Phil Lundrigan, assistant professor of computer engineering at BYU. “In theory, we could install this on almost any Wi-Fi-enabled device with a simple software update.”

The new protocol is called On-Off Noise Power Communication and is programmed right on top of the existing Wi-Fi protocol using the same hardware. While Wi-Fi requires speeds of at least 1 Mbps to maintain a signal, the ONPC protocol can maintain a signal on as low as 1 bit per second.

It works by adjusting the transmitter in a Wi-Fi-enabled device to send wireless noise in addition to data. They programmed into the Wi-Fi sensor a series of 1s and 0s, turning the signal on and off in a specific pattern. The Wi-Fi router was able to distinguish this pattern from the surrounding wireless noise and therefore know that the sensor was still transmitting something, even if the data wasn’t being received.

“If the access point (router) hears this code, it says, ‘OK, I know the sensor is still alive and trying to reach me, it’s just out of range,'” said Neal Patwari of Washington University in St. Louis. “It’s basically sending one bit of information that says it’s alive.”

One bit of information is all many Wi-Fi enabled devices need, said Lundrigran, such as a garage door sensor, an air quality monitor, or a sprinkler system. Along with an application to monitor the ONPC protocol, an off-the-shelf device’s range was extended 67 meters beyond the range of standard Wi-Fi.

The ONPC protocol is not meant to replace Wi-Fi or even long-range wireless protocols like LoRa, but is meant to supplement Wi-Fi. Specifically, only when the team’s monitoring application detects that the Wi-Fi device has lost its connection, it starts transmitting data using ONPC.

Still, they think it could make LoRa even longer range or be used on top of other wireless technologies. “We can send and receive data regardless of what Wi-Fi is doing; all we need is the ability to transmit energy and then receive noise measurements,” Lundrigan said. “We could apply this to cellular or Bluetooth as well.”