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Sugato Hajra,Pichaya In-na,Chalampol Janpum,Swati Panda,Hoe Joon Kim 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.4
Triboelectric nanogenerators (TENGs) are gaining attention for energy supply because of higher demands in decentralizedenergy production. TENGs are known for being self-energy harvesters, converting wasted mechanical energy to usefulelectrical energy under an ambient environment. Advantages of TENGs include a clean energy supply, a wide range ofmaterials selection, and an energy scavenging capability in the ambient environment. However, TENGs still suffer from theirlow electrical outputs compared to existing electrical supplies such as fuel cells and batteries. In bio-photovoltaic (BPV),there has been an interest in the use of microalgae, which are photosynthetic microorganisms capable of carbon capture andgenerating bioelectricity both day and night through electron transport chains via photosynthesis and cell respiration. Toincrease the current output of BPV, many have tried to immobilize living microalgal cells onto electrodes for higher masstransfers leading to higher photosynthetic rates. In this study, we have used immobilized living microalgae (Chlorella sp.)onto aluminium sheets to fabricate the TENG systems and investigate biomechanical energy harvesting. This proof of conceptshows that this integration of microalgae with TENG can enhance the voltage and current output achieved by the dualoperation modes of TENG. One issue raised during the tests was maintaining microalgae alive for several days, which hasgiven opportunities for further studies in nutrient and light supplies to this innovative sustainable hybrid technology. Theresults confirm that the microalgae can be an excellent triboelectric layer in TENG for biomechanical energy harvesting.
Single electrode mode triboelectric nanogenerator (TENG) based on self-aligned microcilia structure
Jungyeun Seo,Sugato Hajra,Hoe Joon Kim(김회준) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
This study proposes a single electrode mode triboelectric nanogenerator (TENG) based on self-aligned microcilia structure. As the demand for sensors increases with the development of the internet of things (IoT), the importance of sustainable energy sources is emerging. Among various energy harvesting system, TENG has drawn much attention due to its unique properties such as high output efficiency and simple structure. We fabricated the microcilia structure to enhance the output performance using carbonyl iron (CI)/PDMS composite and magnet. The cilia structured TENG (CTENG) produced an open-circuit voltage of 70 V, current of 150 nA, and a power density of 2.75 μW/cm2 at 30 MΩ. CTENG can collect the electrical energy from the biomechanical motion such as finger tapping and wind blowing. Further, the ion injection on cilia structure doubled the voltage output. We expected that our device could be utilized for self-powered systems.
Sahu, Manisha,Hajra, Sugato,Choudhary, Ram Naresh Prasad Materials Research Society of Korea 2019 한국재료학회지 Vol.29 No.8
A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.
Kyungtaek Lee,Sugato Hajra,Manisha Sahu,Yogendra Kumar Mishra,김회준 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-
The development of gas sensors with high sensitivity, stability, and selectivity is vital in detecting hazardousgas leaks and monitoring air pollution. The perovskite comprises a stable chemical structureand offers multifunctional properties to act as a base for several device engineering. Specifically, perovskitespossess a great potential for chemical sensors with their semiconducting nature and ease to dopewith other elements to further improve gas sensing properties. In this present study, a rare-earth gadoliniumorthoferrite, GdFeO3 (GFO), and Co-doped GFO were systematically investigated by evaluating theirstructural, morphological, electrical, and gas sensing properties. A high-temperature solid-state reactionsynthesized the phase-pure compounds. The magnetic properties of Co-doped GFO significantlyimproved than pure GFO. The pellet-type gas sensor was fabricated, which does not need any sophisticatedinstrumentation such as microfabrication. When exposed to 20 ppm of NO2 gas, a GdFe0.7Co0.3O3(GFOC3) device gave 6.86% response at 200C, along with a response time of 104 s and the recovery timeof 97 s. Additionally, Co-doped GFO sensors showed a detectable response even at room temperature,enabling- practical applications in an ambient environment. The gas sensor revealed stable gas responsecharacteristics even after several months. Therefore, this study elucidates that the Co-doped GFO has bettergas sensing performance compared to a bare GFO and that it is highly selective towards the NO2 gas.
Accelerate the Shift to Green Energy with PVDF Based Piezoelectric Nanogenerator
Jeonghyeon Lee,Sugato Hajra,Swati Panda,Wonjeong Oh,Yumi Oh,Hyoju Shin,Yogendra Kumar Mishra,Hoe Joon Kim 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.1
The two greatest difficulties humanity faces are environmental catastrophe and air degradation, and renewable energy from the ocean, solar, and wind offers a possible answer. This research describes a piezoelectric energy harvester (PENG) for harvesting low-frequency water wave energy. The poled PENG device based on a ferroelectric polymer polyvinylidene fluoride (PVDF) delivers a voltage of 32 V and a current of 130 nA. The PENG achieves a power of 1.38 µW at 500 MΩ. The low-frequency vibrations generated from the laboratory equipment were effectively converted into usable electrical energy. Furthermore, the output performance of four PVDF-based PENG units connected in parallel was placed inside a 3D printed housing after being exposed to water waves delivered a voltage of 1.1 V and current of 170 nA. This work presents an efficient approach for gathering low-frequency wave energy and realizing the blue-energy dream. This study offers a cost-effective approach for gathering low-frequency water wave energy and realizing the blue-energy vision.