My publications


Bhaskar Dudem, Sontyana Adonijah Graham, RD Ishara G Dharmasena, S Ravi P Silva, Jae Su Yu (2021). Natural silk-composite enabled versatile robust triboelectric nanogenerators for smart applications, Nano Energy
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Strategies to maximize the surface charge density across triboelectric layers while protecting it from humidity are crucial in employing triboelectric nanogenerators (TENGs) for commercial/real-time applications. Herein, for the first time, we propose the utility of crystalline silk microparticles (SMPs) to improve the surface charge density in materials like polyvinyl alcohol to realise its applicability for TENG devices. Moreover, these SMPs are extracted from discarded  silkworm cocoons by facile, inexpensive, and single-step alkaline-hydrolysis treatment. We examine the performance of these composites with counter-materials composed of waste PTFE plastic cups to show reuse in recycled products. The processing cost of TENG developed from recycled materials is not only low but eco-friendly. The TENG performance as a function of the concentration of SMPs is investigated and compared with the composite's work-function and surface-potentials, with the distance-dependent electric field theoretical model employed to optimize the performance. Consequently, the optimized TENG exhibits maximum output voltage, current, charge, and power density of ∼280 V, 17.3 μA, 32.5 nC, and 14.4 W·m−2, respectively, creating a highly competitive energy harvester that can conform to the rigorous needs of wearables and mobile applications. Furthermore, the fully packaged silicone rubber device protects it from humidity and enables the device utility for practical applications with a soft, comfortable, and skin-friendly interface.
Bombyx mori
Bhaskar Dudem, RD Ishara G Dharmasena, Sontyana Adonijah Graham, Jung Woo Leem, Harishkumarreddy Patnam, Anki Reddy Mule, S Ravi P Silva, Jae Su Yu (2020). Exploring the theoretical and experimental optimization of high-performance triboelectric nanogenerators using microarchitectured silk cocoon films, Nano Energy
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Triboelectric nanogenerators (TENGs) developed using eco-friendly natural materials instead of traditional electronic materials are more favorable for biocompatible applications, as well as from a sustainable life-cycle analysis perspective. Microarchitectured silkworm fibroin films with high surface roughness and an outstanding ability to lose electrons are used to design TENGs. An alcohol-annealing treatment is utilized to strengthen the resistance of the silk film (SF) against humidity and aqueous solubility. Herein, for the first time, the distance-dependent electric field theoretical model is employed to optimize the TENG parameters to achieve high output, which shows excellent agreement with the experimental outputs of SF-based TENG. The alcohol-treated microarchitectured SF (AT-MASF) with a polytetrafluoroethylene positive contact exhibits a stable and high electrical output even in harsh environments. These studies can lead us closer to the attractive future vision of realizing biodegradable TENG systems for harness/sensing various biomechanical activities even under real/humid environments. The potential and real-time application of the proposed AT-MASF-based TENG is demonstrated by directly employing its electric power to drive a number of low-power portable electronics and for sensing in human-body centric activities.
Sontyana Adonijah Graham, Bhaskar Dudem, Harishkumarreddy Patnam, Anki Reddy Mule, Jae Su Yu (2020). Integrated Design of Highly Porous Cellulose-Loaded Polymer-Based Triboelectric Films toward Flexible, Humidity-Resistant, and Sustainable Mechanical Energy Harvesters, ACS Energy Letters
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A wearable and humidity-resistant cellulose-based flexible triboelectric nanogenerator (FTENG) device with high performance is proposed here. In this regard, cellulose extracted from cotton was combined with a poly(vinyl alcohol) solution and spray-coated onto a conductive–flexible substrate to develop a highly porous and flexible triboelectric film (HPF) which was employed in the fabrication of a FTENG. The dependence of electrical performance on the surface area was comprehensively studied by varying the surface area of the HPF. Furthermore, the HPF-based FTENG (HPF-FTENG) is lightweight, flexible, and robust; has a low processing cost; and can withstand a humid environment. Thus, the proposed device can be used not only to scavenge various mechanical disturbances within the surrounding environment but also to harvest mechanical energy underwater and in harsh environmental conditions. Finally, the electricity generated by the HPF-FTENG was employed to power various portable electronics, which supports a paradigm shift in the context of wearable and durable mechanical energy harvesters.