E-Skin transmits Glucose Concentrations, Blood Pressure, Heart Rate, to Your Smartphone

Wearable sensors are ubiquitous thanks to wireless technology that enables a person’s glucose concentrations, blood pressure, heart rate, and activity levels to be transmitted seamlessly from sensor to smartphone for further analysis. Most wireless sensors today communicate via embedded Bluetooth chips that are themselves powered by small batteries. But these conventional chips and power sources will likely be too bulky for next-generation sensors, which are taking on smaller, thinner, more flexible forms.

Now MIT engineers have devised a new kind of wearable sensor that communicates wirelessly without requiring onboard chips or batteries. Their design, detailed today in the journal Science, opens a path toward chip-free wireless sensors. The team’s sensor design is a form of electronic skin, or “e-skin” — a flexible, semiconducting film that conforms to the skin like electronic Scotch tape. The heart of the sensor is an ultrathin, high-quality film of gallium nitride, a material that is known for its piezoelectric properties, meaning that it can both produce an electrical signal in response to mechanical strain and mechanically vibrate in response to an electrical impulse. The researchers found they could harness gallium nitride’s two-way piezoelectric properties and use the material simultaneously for both sensing and wireless communication.

In their new study, the team produced pure, single-crystalline samples of gallium nitride, which they paired with a conducting layer of gold to boost any incoming or outgoing electrical signal. They showed that the device was sensitive enough to vibrate in response to a person’s heartbeat, as well as the salt in their sweat, and that the material’s vibrations generated an electrical signal that could be read by a nearby receiver. In this way, the device was able to wirelessly transmit sensing information, without the need for a chip or battery.

Chips require a lot of power, but our device could make a system very light without having any chips that are power-hungry,” says the study’s corresponding author, Jeehwan Kim, an associate professor of mechanical engineering and of materials science, and a principal investigator in the Research Laboratory of Electronics. “You could put it on your body like a bandage, and paired with a wireless reader on your cellphone, you could wirelessly monitor your pulse, sweat, and other biological signals.”

Jeehwan Kim’s group previously developed a technique, called remote epitaxy, that they have employed to quickly grow and peel away ultrathin, high-quality semiconductors from wafers coated with graphene. Using this technique, they have fabricated and explored various flexible, multifunctional electronic films. In their new study, the engineers used the same technique to peel away ultrathin single-crystalline films of gallium nitride, which in its pure, defect-free form is a highly sensitive piezoelectric material.

The team looked to use a pure film of gallium nitride as both a sensor and a wireless communicator of surface acoustic waves, which are essentially vibrations across the films. The patterns of these waves can indicate a person’s heart rate, or even more subtly, the presence of certain compounds on the skin, such as salt in sweat.

Source: https://news.mit.edu/

Artificial Skin Recreates The Human Sense Of Pain

Prosthetic technology has taken huge strides in the last decade, but accurately simulating human-like sensation is a difficult task. New “electronic skin” technology developed at the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in Korea could help replicate advanced “pain” sensations in prosthetics, and enable robots to understand tactile feedback, like the feeling of being pricked, or that of heat on skin.

Trying to recreate the human senses has been a driver of technologies throughout the 20thcentury, like TV or audio playback. Mimicry of tactile sensing has been a focus of several different research groups in the last few years, but advances have mainly improved the feeling of pressure and strength in prosthetics. Human sensation, however, can detect much more subtle cues. The DGIST researchers, led by Department of Information and Communication Engineering Professor Jae Eun Jang, needed to bring together expertise from several different fields to begin the arduous task of replicating these more complex sensations in their electronic skin, working with colleagues in DGIST’s Robotics and Brain Sciences departments.

“We have developed a core base technology that can effectively detect pain, which is necessary for developing future-type tactile sensor. As an achievement of convergence research by experts in nano engineering, electronic engineering, robotics engineering, and brain sciences, it will be widely applied on electronic skin that feels various senses as well as new human-machine interactions.” Jang explained.

The DGIST team effort has created a more efficient sensor technology, able to simultaneously detect pressure and heat. They also developed a signal processing system that adjusted pain responses depending on pressure, area, and temperature.

Source: https://www.dgist.ac.kr/