Chung-Ang University researchers breathe life


image: In a new study, researchers at Chung-Ang University design a sensor based on a high-power, high-efficiency triboelectric nanogenerator (TENG) that can be powered by breathing. The researchers integrated this device into a gas mask to create a self-powered hybrid sensor that detects breathing patterns and harmful chemicals.
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Credit: Prof. Sangmin Lee from Chung-Ang University, Korea

With the onset of the Internet of Things (IoT) era, devices have learned to communicate and exchange data. This is achieved through sensors installed in physical objects, machines and equipment. Sensors can detect changes in events. However, the need for a continuous power supply to these sensors poses a challenge. Batteries are bulky, expensive and environmentally unfriendly. In addition, they must be constantly replaced or recharged.

Therefore, there is a demand for sustainable and renewable energy sources to replace batteries. The triboelectric nanogenerator (TENG) is one such device. Simply put, TENGs convert mechanical energy into electrical energy. Their high energy efficiency, compatibility with readily available materials, and low cost make them a promising candidate for sensor power supplies.

Despite these advantages, however, current TENGs are limited by low output current. But increasing the output current would require larger equipment, making it impossible to use in small devices. Is there a way around this compromise?

Fortunately, a research team led by Associate Professor Sangmin Lee of Chung-Ang University in Korea has looked into this question. “Our lab is interested in high-power TENG design and self-powered sensors based on TENG. We sought to address the limitation of current TENGs so that they could be used to realize portable power sources in the practice “, says Dr. Lee, explaining his motivation behind the study, which was posted on May 31, 2022 in Advanced Energy Materials. The study will be featured on the cover of the next issue.

The team developed a new device in their study called the Inhalation-Driven Vertical Flutter TENG (IVF-TENG) that features an amplified current output. “The breath acts as a continuous mechanical input and can be used to operate TENGs. Film-floating TENGs are such breath-driven devices that can generate a continuous electrical output from an extremely low respiratory input by exploiting the phenomenon of flutter resulting from vibrations induced by the airflow.”, explains Dr. Lee.

The IVF-TENG is composed of an aluminum (Al) input electrode, an aeroelastic (polyimide) dielectric sheet and an Al output electrode. The aeroelastic sheet has four segments with four slots and is subjected to vertical flutter behavior caused by the airflow. This makes the proposed IVF-TENG different from existing TENGs.

The team studied the electrical and mechanical mechanisms of IVF-TENG. They found that IVF-TENG generated a high-frequency DC voltage (17 V) and a closed-circuit current of 1.84 μA during inhalation, as well as an electrostatic discharge voltage of 456 V and a current closed-circuit output of 288 mA at the start and end of each inspiratory cycle.

They further demonstrated that IVF-TENG can continuously power 130 LEDs in series and 140 LEDs in parallel with each inhalation. Additionally, it could charge a 660 𝜇F capacitor to, in turn, power a Bluetooth tracker and deliver its signal to a smartphone. These properties demonstrated the application potential of IVF-TENG in portable electronics and wireless data transmission.

Additionally, researchers integrated IVF-TENG into a gas mask and demonstrated its ability to monitor the user’s breathing pattern by observing the output response waveform. Additionally, it could detect chemical warfare agents like cyanogen chloride, sarin, and dimethyl methylphosphonate (DMMP), showing its potential for emergency use. “Since gas masks are widely used in emergency situations such as fires and exposure to chemical gases, we focused on applying TENG to a gas mask. We believe IVF-TENG can be used as a self-powered sensor in such scenarios,” Dr. Lee speculates.

Indeed, their invention could cause TENGs to reinvent gas masks as a self-powered hybrid detection system in the near future!




Author: Deokjae Heo1Song Myunghwan1Seh Hoon Chung1Kyunghwan Cha1Youna Kim2Jihoon Chung2Patrick TJ Hwang3Jaeheon Lee4Heesoo Jung4Youngho Jin4Jinkee Hong2Min Kun Kim4and Sangmin Lee1

1School of Mechanical Engineering, Chung-Ang University
2Department of Chemical and Biomolecular Engineering, College of Engineering, Yonsei University
3Department of Biomedical Engineering, University of Alabama at Birmingham
4Defense Development Agency, Chem-Bio Technology Center

About Chung-Ang University
Chung-Ang University is a private comprehensive research university located in Seoul, South Korea. It was started as a kindergarten in 1916 and gained university status in 1953. It is fully accredited by the Ministry of Education of Korea. Chung-Ang University conducts research activities under the slogan “Justice and Truth.” Its new vision to end its 100 years is “The world leader in creation”. Chung-Ang University offers undergraduate, postgraduate, and doctoral programs, which encompass a law school, a management program, and a medical school; it has 16 undergraduate and graduate schools each. Chung-Ang University’s cultural and artistic programs are considered the best in Korea.

About Associate Professor Sangmin Lee
Dr. Sangmin Lee obtained his Ph.D. in Mechanical Engineering from Pohang University of Science and Technology (POSTECH) in 2011. He teaches at Chung-Ang University where he is an Associate Professor in the School of Mechanical Engineering. His group carries out research in the field of energy harvesting based on electrostatic potential, piezoelectric/triboelectric nanogenerators and hybrid cells. His research interests also relate to the control of surface wetting, including superhydrophobicity/superhydrophilicity based on micro and nanofabrications, and the mechanical characterization of micro and nanostructure surfaces.

Read more about Professor Lee here:

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