This study used a five-chapter format to achieve the above-stated research purpose. Chapter one of the study was used to introduce the topics under consideration, provide a statement of the problem, the purpose and importance of the study, as well as its scope and rationale. Chapter two provides a critical review of the relevant and peer-reviewed literature, and chapter three more fully describes the study's methodology, including a description of the study approach, the data-gathering method and the database of study consulted. Chapter four is comprised of an analysis of the data developed during the research process and chapter five presents the study's conclusions, a summary of the research and recommendations for improvements to the device prototyped and envisioned herein.
Chapter 2: Review of Related Literature
It is reasonable to suggest that all battery-powered handheld device users have experienced battery failure at a critical juncture, whether it is making an important or even emergency call on a cell phone, uploading an assignment to school, or downloading critically important corporate data on a personal digital assistance, tablet computer or similar devices. In this regard, Clinton and Kantrakirschner ask, "Why is it that more and more we find ourselves pushing the 'on' button and watching the sad spectacle of nothing going on?" (2004, p. 58). The reason for this failure, of course, is the limited amount of power that conventional batteries are capable of providing, with some of the more power-hungry devices such as multifunction cell phones, laptop and notebook computers that require battery replacements after just an hour's use (Clinton & Kantrakirschner 2004). As an example of such energy-intensive devices, Clinton and Kantrakirschner cite the Nokia 7700 which provides the following features:
1. A 65,546-color touch screen with 640x320-pixel resolution,
2. A Web browser;
3. Audio and video playback;
4. FM radio;
5. Built-in camera;
6. Voice recording;
7. Bluetooth connectivity;
8. Personal-information-management software, word processing, spreadsheet and presentation viewers.
This veritable "Swiss army knife" of mobile devices was engineered to provide between just 3 and 4 hours of telephone use only, and this performance is severely diminished if any of the other features are used (Clinton & Kantrakirschner 2004). According to a senior analyst for the technology consulting firm IDC, "Everybody wants more in the way of functionality, everybody wants more in the way of capabilities. They wish their iPod had a color screen. Vendors are trying to pack in more processing power; better, brighter, deeper displays; better audio capability; 3-D accelerators for graphics; more storage. And the reality is, battery life is extremely limited" (quoted in Clinton & Kantrakirschner 2004, at p. 60). Not surprisingly, researchers have been actively involved in seeking improvements in conventional battery design and performance, as well as reducing the energy requirements for existing devices. To date, at least some progress has been made as can be seen from the power requirements needed for three-megapixel digital camera model shown in Figure 5 below.
Figure 5. Average Power Requirements for 3MP Digicams: 2002-2004
Source: Based on tabular data in Clinton & Kantrakirschner 2004, p. 60
Other improvements in performance have also been developed in screen displays and hard drives for mobile computers, but the fact remains that while this research continues, the marketplace is being flooded with other multi-feature devices that remain energy-intensive and require frequent battery replacements. For instance, a recent report from Denison (2011) emphasizes that, "As the technology built into battery powered devices like laptops and cell phones advances, so does their demand for power. it's great that your cell phone can now act as a fully functional GPS device and HD video player, but it starts looking a lot less attractive when its battery life is knocked out in a matter of minutes" (p. 2).
While these multi-feature devices continue to be improved in their performance, the constant addition of yet more functionalities has created a Catch-22 cycle wherein researchers have been more efficient in incorporating additional features in hand-held mobile devices than they have in the battery technology that is required to power them (Yildiz 2009). According to this authority, "The critical long-term solution should therefore be independent of the limited energy available during the functioning or operating of such devices" (Yildiz 2009, p. 4). There are some potentially long-term solutions available, though, and Table 1 below compares the estimated power and challenges of various ambient energy sources in a recent study by Yildiz, Zhu, Pecen, and Guo (2007).
Comparison of Power Density of Energy Harvesting Methods
Power Density & Performance
Source of Information
(Rabaey, Ammer, Da Silva Jr.,
Patel, & Roundy, 2000)
(Roundy, Steingart, Frechette,
Wright, Rabaey, 2004)
Ambient Radio Frequency
100 mW/cm2 (direct sun)
100 _W/cm2 (illuminated office)
4 _W/cm3 (human motion -- Hz)
800 _W/cm3 (machines -- kHz)
(Mitcheson, Green, Yeatman, & Holmes, 2004)
(Roundy, Wright, & Pister, 2002)
(Paradiso & Feldmeier, 2001)
(Shenck & Paradiso, 2001)
(Starner & Paradiso, 2004)
(Shenck & Paradiso, 2001)
The stated values in Table 1 above were based on data presented in archived studies, textbooks, as well as empirical research conducted by Yildez et al. (2007). While this comparison is exhaustive, the comparisons do confirm that a wide array of potential alternatives to conventional batteries is available (Yildez et al. 2009).
Although a wide range of energy harvesting techniques are available, most are inadequate for the power-hungry mobile devices that are currently on the market, and all signs indicate that these devices will continue to incorporate yet further features in the future, making an alternative energy source all the more important. At present, there is no single energy-harvesting method available that is capable of generating sufficient power for every application, and the choice of method must be based on the type of application that is intended. Some of the currently available energy-harvesting methods include those summarized in Table 2 below:
Currently available energy-harvesting sources
Mechanical and thermal (heat variations) energy can be generated from a human or animal body by actions such as walking and running.
Wind, water flow, ocean waves, and solar energy can provide limitless energy availability from the environment.
Vibrations from machines, mechanical stress, strain from high-pressure motors, manufacturing machines, and waste rotations can be captured and used as ambient mechanical energy sources.
Waste heat energy variations from furnaces, heaters, and friction sources.
This source can be divided into two categories of energy: indoor room light and outdoor sunlight energy. Light energy can be captured via photo sensors, photo diodes, and solar photovoltaic (PV) panels.
Inductors, coils, and transformers can be considered as ambient energy sources, depending on how much energy is needed for the application.
Source: Yildiz 2009
Figure 6 below shows a block diagram of general ambient energy-harvesting systems developed by Yildiz (2009). The first row of Figure 6 indicates the energy-harvesting sources; the second row of Figure 6 indicates actual implementation and tools that are employed to harvest the energy from the source; and the third row of Figure 6 indicates the energy-harvesting techniques used with each source.
Figure 6. Ambient Energy Systems
Source: Yildiz 2009
Taken together, it is clear that a significant problem has been created by the introduction of a wide range of energy-hungry mobile wireless devices in recent years, and the research was consistent in showing that these trends are expected to continue well into the foreseeable future. At the same time, despite ongoing intensive research, conventional battery technology remains relatively stagnated, suggesting that things are going to get worse before they get better unless and until a viable alternative power source can be developed to help power these mobile devices. To help address this need, the solution proposed herein may help fill the energy gap that will continue to widen and the methodology by which this project was developed is discussed further below.
Chapter 3: Methodology
Description of the Study Approach
This study used a literature review as its study approach. According to Fraenkel and Wallen, "researchers usually dig into the literature to find out what has already been written about the topic they are interested in investigating. Both the opinions of experts in the field and other research studies are of interest. Such reading is referred to as a review of the literature" (2001, p. 48). This approach is consistent with the guidance provided by numerous researchers who emphasize the need to review what is known about a given topic before developing conclusions and formulating opinions (Neuman…