In recent times, Triboelectricity and Piezoelectricity has been widely used for utilizing mechanical energy from ambient environment. Scientists are focusing towards developing advanced material composites for utilizing piezoelectricity and triboelectricity for energy harvesting and sensory applications. This work includes two projects regarding the application of lead free piezoelectric and triboelectric energy for energy harvesting and sensory applications. Human motion has been attributed as a source of mechanical energy to drive electronic devices and sensors through Triboelectric Nanogenerator (TENG). Based on the principles of single electrode TENG, we have developed a Triboelectricity based Stepping and Tapping Energy Case (TESTEC) which magnifies the prospect to power touch electronic devices by utilizing finger tapping and stepping motion. This novel case was constructed with two single electrode TENG operating through the triboelectric mechanism between human skin and Polyethylene terephthalate (PET) film on the front part and Nitrile Butadiene Rubber (NBR) and PET film on the back part. This cost effective device was further tested by attaching with a cell phone at variable load frequency, airgap and finger combinations where the output response increased with the increased frequencies (60 to 240 BPM) and air gap (1cm to 5cm). Maximum output voltages of 14.8 V and 50.8 V were obtained for the front and back parts, respectively. Besides, maximum output powers were observed to be 3.78 W/m2 at 0.46 MΩ and 6.21 W/m2 at 1.02 MΩ, respectively. Also, the device was tested by integrating with conventional electronic components including capacitors, bridge rectifiers and 15 LEDs. Based on the results, a electrical circuit has been proposed to power touch cell phones. The device was further modified using Silver (Ag) nanoparticles in the front part. The modified TESTEC provided higher output response compared to the primary TESTEC. The TESTEC can be a self sustainable way to power touch electronic devices which can reduce the necessity to charge electronics devices in the conventional way. In the second part of this work, a Potassium Sodium Niobate (KNN) nanocube based energy film (EF) has been developed for utilizing mechanical Energy through triboelectric and piezoelectric mechanism. The KNN particles were synthesized using wet ball milling technique incorporated into Polyvinylidene Difluoride (PVDF) matrix and along with Multi Wall Carbon Nanotube (MWCNT). The film was used to develop a Piezoelectric Nanogenerator (PENG) with Copper electrodes. The piezoelectric output of the film was further tested with Copper electrodes at variable tapping frequency (60 BPM to 240 BPM) and Pressure (10 PSI to 40 PSI). The open circuit voltage increased with the increase of both tapping frequency and pressure. The maximum piezoelectric output voltage was observed to be 35.3 V while the maximum current was noted as 15.8 µA. The films also showed unique output signals for different types of finger motions. The film was further utilized to build a Piezo-triboelectric hybrid nanogenerator to check its hybrid performance. The maximum output was observed to be 54.1 V and 29.4 µA in this case. This film was integrated with conventional electronic component (bridge rectifiers, resistors and capacitors) and tested its ability to harvest energy. The hybrid nanogenerator can charge a 0.1µF capacitor to 9.4 V in 60s. Besides, the optimum output power for the device was measured as 0.164 W. The film was further attached with a Kapton film and showed a hybrid output of 113.2 V. This experiment endorsed the potential of the KNN based energy film for multifunctional application like force, pressure and motion sensing as well as lead free energy harvesting.
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|Advisor:||Uddin, M. Jasim|
|Commitee:||Vasquez, Horacio, Yang, Yingchen|
|School:||The University of Texas Rio Grande Valley|
|Department:||Department of Mechanical Engineering|
|School Location:||United States -- Texas|
|Source:||MAI 82/9(E), Masters Abstracts International|
|Subjects:||Mechanical engineering, Nanotechnology|
|Keywords:||Lead-free energy film, Mechanical energy scavenging, Nanogenerator, Piezoelectricity, Sensor, Triboelectricity, Energy harvesting|
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