KU and UNIST Researchers Develop Self-sustaining Environmental Sensor System
▲ Prof. Wonjoon Choi (Korea University, corresponding author), Jaehyouk Choi (UNIST, corresponding author), Taeho Seong (UNIST, first author), and Dongjoon Shin (Korea University, first author)
A research team, led by professors from Korea University and UNIST, has developed a self-sustaining sensor system for the continuous monitoring of environmental changes.
According to the National Research Foundation (NRF) of Korea, “The team has succeeded in developing a self-sustaining sensor platform for real-time observations and analysis of changes in the environment.” This opens up new possibilities in resolving the problem of power sources for the internet-of-things (IoT).
*Sensor platform: A hardware device used to operate multiple sensors.
The team, led by Professor Wonjoon Choi of Korea University and Professor Jaehyouk Choi of UNIST, chose water as the primary subject for monitoring. Their self-sustaining system, which does not require any external power, is an integrated platform that analyzes electrical energy in real-time using energy generated on its own and presents water motion information.
The triboelectric nanogenerator generated electrical energy when water came into contact with a solid surface. The solid surface becomes polarized due to friction with water, and energy is produced because the change in contact area breaks the electrical equilibrium and creates more water-droplet polarizations.
*Triboelectric nanogenerator: A device that generates electricity when a material comes into contact with a certain solid surface.
*Polarization: The generation of positive and negative charges at each end when a dielectric substance is placed in an electric field.
*Electron: Particles that transport negative electric charges.
The team employed a CMOS circuit for energy storage and data analysis, thereby allowing the device to be easily commercialized at low costs. The analyzed information is displayed on multiple LEDs based on a 6-bit binary code.
*Complementary metal–oxide–semiconductor: A technology used to construct integrated circuits on P-type and N-type substrates; widely used in digital circuits, such as microprocessors and memories, and analog/RF circuits.
According to the research team, the significance of the study lies in the development of a next-generation sensor system capable of continuously monitoring water motion with energy generated on its own. The team expects the system to be used in environment sensors for ocean currents, flow rate and velocity in rivers and waterworks, rainfall, precipitation per hour, and liquid flow and in self-sustaining monitoring systems in related industries.
Supported by the Basic Science Research Program under the National Research Foundation of Korea, the Ministry of Education, and the Ministry of Science, ICT and Future Planning, this study was published in Nano Energy on March 29.
- Title: Self-sustaining water-motion sensor platform for continuous monitoring of frequency and amplitude dynamics
- Author information: Jaehyouk Choi (UNIST, corresponding author), Wonjoon Choi (Korea University, corresponding author), Taeho Seong (UNIST, first author), and Dongjoon Shin (Korea University, first author)
Nano Energy: an international journal with a focus on nanomaterials and devices used in all types of energy harvesting, conversion, storage and applications. (IF: 11.553)
CMOS: Complementary metal–oxide–semiconductor (CMOS), a technology for the construction of integrated circuits, is widely used in digital circuits, such as microprocessors and memories, and analog/RF circuits. It is known for its economic feasibility and low power consumption.
Triboelectric nanogenerator: WC-TENG refers to a device that generates electricity due to the triboelectric effect when water comes into contact with a certain solid surface. When water droplets come into contact with a material that can be easily charged, the friction between water molecules and the solid surface causes charges to move to one side. The polarized water droplets amplify the electric field, which breaks the electrical equilibrium. The electric charges move to return to the equilibrium state, and electrical energy is generated in this process.
Description of Figures:
Fig. 1: Scheme of the self-sustaining sensor platform for detecting water motion.
When a water droplet is subject to oscillatory pressurization, the contact area at the interface between the water droplet and electrodes changes according to the distance between electrodes. The polarized area changes at the same time, and the resulting electrical energy is proportionate to the rate of change of the contact area. An analysis of the electrical energy through the CMOS circuit provides information on the frequency and amplitude of the water motion. The energy produced by friction between the water drop and electrodes is rectified through the CMOS circuit and powers the six LEDs responsible for sending out signals. The information on water motion is delivered via the on/off state of the LEDs.
Fig. 2: Output signals of the self-sustaining sensor platform in relation to frequency and amplitude.
The images show the LED output signals produced by the self-sustaining sensor platform in relation to frequency and amplitude when a water droplet is subject to oscillatory pressurization using a linear motor. The LED was operated with electrical energy generated by the WC-TENG and rectified through the CMOS IC. The contact area at the interface of the water drop and electrodes increases with the frequency of the linear motor. The binary LED output signal values decreased as the period decreased with increasing frequency. Similarly, when the stroke depth of the linear motor is increased for greater pressurization of the water droplet, the contact area undergoes larger changes. The voltage signals grow larger and bigger binary LED output signals are obtained indicating that the sensor platform is performing well.