| Summary: | 碩士 === 國立交通大學 === 電信工程研究所 === 103 === Energy harvesting is the process of scavenging energy from ambient energy sources in environment to serve as power supply for low-power electronics devices. By Micro-Electro-Mechanical System (MEMS) fabrication technology, energy harvesting system can be integrated with low-power devices. For invasive devices in biomedical applications, batteries are discouraged due to its cost of operations for replacement. Therefore, energy harvesting is more suitable then batteries for low-power devices. Human motion which is usually complicated and aperiodic can be an energy source. Flexible energy harvesters can scavenge energy from human motion by attaching them to human bodies, and power up low-power devices.
In this thesis, electrostatic flexible electret energy harvesters for human motion are proposed. For flexibility and biocompatibility, the substrate was polydimethylsiloxane (PDMS) and Parylene C was used as electret. In our previous work, the sputtered electrode were prone to cracks upon the deformation of the devices, thus limiting the lifetime. To improve the reliability, flexible electret energy harvesters with embedded copper mesh are proposed. In this thesis, two prototypes of energy harvesters have been fabricated. Prototype I has square spacer of rings and is suitable for harvesting energy from walking. Prototype II has arrays of spacer posts and is suitable for harvesting energy from finger typing. The output power for the two prototypes were 3.15 μW and 2.26 μW, corresponding to power density of 15 μW/cm3 and 23 μW/cm3 at test frequency of 20 Hz with a 1000-MΩ load, respectively. In human motion test, the harvester was attached to a human finger. With a 1000-MΩ load, the output power were approximately 300 nW for finger tapping, and 5 nW for finger bending.
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