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Author: Verma, Harsh Kumar × End date: 2024 × Start date: 2020 × Item Type: Publication ×

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Sound sensing B.A.T.S. - Biodegradable acoustic triboelectric nanogenerator sensors

2024-04-15 , Verma, Harsh Kumar

Two of the prominent challenges facing modern development of electronic devices are minimizing their power requirements and simplifying the disposal processes. Recent developments in self-powered energy harvesters such as triboelectric nanogenerators (TENGs) have been extensively focused on the use of more environmentally sustainable materials to minimize the environmental impact while being able to harvest energy from the environment. In this thesis, I have investigated 3 different versions of biodegradable triboelectric nanogenerators for acoustic energy harvesting, referred to as biodegradable acoustic triboelectric nanogenerator sensors (BATS). To study the negative layer, I use a tribonegative biopolymer, poly (L-lactic acid) and compare the voltage outputs of the device to traditional materials such as FEP. These results indicated good usability of PLLA based BATS, albeit an order of magnitude lower signal than for FEP based BATS. I also examined how the polymer crystallinity and volatile content in the PLLA films impacts the performance. To study the positive layer, I selected silk fibroin as a tribopositive biopolymer. Variation in voltage output was observed and correlated to changes in drying temperature and the water uptake of the polymer, demonstrating the dependence of the TENG performance on the dynamic behavior of the biopolymers and the environmental conditions. Lastly, I used a contact separation mode for the TENG and examined the combined effects of the triboelectric biopolymers PLLA and silk fibroin on the TENG performance. A shift in the resonant frequency was observed in these devices over time due to the hygroscopic property of both PLLA and silk fibroin. As in the previous cases, the reduction in voltage was observed and correlated with the reducing residual solvent in the films over time. Overall, residual solvent after processing and water absorption, measured by changes in the volatile content of the polymer, were found to be a major factor significantly affecting the properties of the triboelectric layers. Optimizing the processing conditions and the solvents used for these polymers is crucial, as this not only affects their triboelectric property but also, the changes in TENG performance over time.

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Friendly green OWLS and sound sensing BATS: Biodegradable flexible acoustic sensor and a consumer centric approach towards sustainability

2024-02-08 , Verma, Harsh Kumar , Hester, Josiah , Brettmann, Blair , Arora, Nivedita

With new technological advancements every decade, devices are becoming smaller, faster, and cheaper. The latest advances in flexible and wearable electronic devices have opened myriad opportunities for applications in fields like robotics, safety and security, healthcare, and IoT devices like flexible smartphones. While this has provided an opportunity to add computational capabilities to everyday objects, it has also made us think about their environmental impacts. Unchecked manufacturing and disposal methods still remain a major challenge. Not to mention the harmful waste from batteries and the electronic waste generated every year. To tackle these challenges, we must think about sustainability as a metric beyond performance and functionality. We must talk about sustainability at every stage of the life cycle of a device. In this project, we introduce a Biodegradable Acoustic Triboelectric Sensor (BATS), a biodegradable flexible microphone based on triboelectric nanogenerators. This project focuses on using environmentally benign processes and chemicals for manufacturing, combined with battery-free operation and biodegradable materials like silk, PLLA, and paper for convenient disposal. Additionally, to make sustainability a consumer-centric subject, we present an Open Way to Look at Sustainability (OWLS), a visual representation of sustainability for our microphone, emphasizing chemical usage, emissions, material selection, and the manufacturing and disposal processes. This idea takes inspiration from nutrition labels on food packaging and energy ratings on electrical equipment that allow a consumer to make the right choices for better nutrition or to save energy and can be more broadly applied to other consumer products in the future.

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