1.Introduction



1)Introduction

    
As you know over the past few years the amount of people using smartphones in Singapore have increased.In 2013 Singapore was ranked in the top 4 countries for smartphone market penetration.(as stated by : the Link) From there we can also see that 71.7% of the people in Singapore uses smartphones. Singaporeans tend to use their phones while on the move.(supported by : the Link) An example from the link is that 74% of people say they use mobile web when they are “outside”. Take note that the link shows that the people use mobile web and they do not use it for normal usage.

As most smartphones rely on 3G connection, it can be inferred that they will use 3G to access mobile web.This can lead to a faster draining of phone battery as 3G uses up battery faster. “2G (original GSM) was deliberately designed to be very power-efficient only for low-data rate voice services. 3G was designed to be more spectrally efficient and to deliver higher-rate data services, but at the expense of using more power. 4G offers far faster data rates and is more spectrally efficient, but draws even more power.”As quoted from the following site it proves that 3G drains a lot of the smartphone’s power.

When they are outside they cannot usually find a socket to charge their phones so they will have to rely on a portable charger when their phones are running low on battery. So people starts buying power banks to solve this problem. According to the findings of the survey we conducted in school 82% of the people who owns a portable charger said that they do use their portable charger once a day. This shows that people are using portable chargers to be able to use mobile web/3G while on the go.

Therefore we decided to make a kinetic shoe charger. It would be a convenient device that will charge the power bank which will be strapped to the side of the user’s leg whenever he/she walks.This power bank will then be used by the users to charge their phones when their batteries are running out.

Research:

Even most smartphones, are able to last for about 6 to 8 hours on average before running out of battery, which is much longer than what people use when outside. But with the usage of a whole variety of apps, 3G, Wifi and even worse, 4G, a battery’s life span would be mostly, if not totally spent, by the time the users return home. When those people somehow forget to charge their phone, they would be deprived of their phone usage. Even worse, some people’s phones run out in the middle of their trip or time outside home. Thus, the advent of the powerbank, a device that acts as a portable charger outside home, was much welcomed. But it still relies on other non-portable chargers for it to work outside, people can also forget to charge it, and would really be stranded. Those without power banks, meanwhile, would have to watch carefully over their battery usage.


Other 3 Alternatives ways to our project

1) One alternative for our project is a solar power charger.The solar charger employs solar energy to supply electricity to devices or charge batteries. They are generally portable.
Solar chargers can charge lead acid or Ni-Cd battery bank up to 48 V and hundreds of ampere-hours (up to 400 Ah) capacity. For such type of solar chargers, generally intelligent charge controllers are used. A series of solar cell array plates are installed separately on roof top and can be connected to battery bank. Solar chargers today use various types of solar panels, ranging from the inefficient thin film panels with 10% efficiency or less, to the much more efficient mono crystalline panels which offer efficiencies up to 19%. The solar charger is not efficient enough as it is not reliable as there will not always be sunlight everyday and the chargers take a long time to charge even with the sunlight around.

2) We can use potatoes in the shoe to charge the phone. Inserting zinc into potato slices in the shoes will work if we connect it the USB cable to it, since the wire is made out of copper. The zinc will be slowly eaten away by the phosphoric acid in the potato, releasing the zinc electrons to join the hydrogen ions to create hydrogen gas. Electrons in the copper wire in the cable will get to the zinc and voila! However, it is not feasible as the potato will rot and the energy that will be produced will be too low.

3)  Another alternative for our project is a bike-powered generator. Now, there are other bike-powered generators out there. The most common (and cheapest) type is known as a bottle cap generator. It's essentially a contraption that is mounted to your frame or seat-post and has a little bottle cap-like wheel that is spun by your spinning tire. They are, however, not super reliable, as it's pretty easy for the cap to become disengaged with the wheel. They also aren't particularly efficient—they typically hover around 50 percent efficiency, with some high-end models claiming as much as 70 percent. We cannot use this project as it will take quite some time to build and is much more advanced than our current project.


Our solution:


As our project is aimed at the ordinary citizen who uses his phone extensively when outside. With our revolutionary product, we will ensure that this would be the future of a new advancement - not only for mobile appliances but for the race for a new renewable energy source for our world's future! It is a kinetic phone charger using shoes! It makes use of piezoelectric elements,which produce current when stepped on, to charge a power bank that would be attached at the side of the battery. We felt that this is the best solution as it is going to make a huge impact on the use of eco-friendly products and if it works this would be a new source of renewable source of energy.
   
Research Questions:    

1.  How do we harness energy such that we can use it as DC-electrical energy?
2)  How do we make sure that the components are compact enough to fit in the shoe?
3) How do we make sure the current produced is powerful enough to charge a powerbank or phone in a reasonable amount time?  

Hypothesises:
1) A bridge diode can be used to convert the AC electrical energy produced by the piezoelectric discs to DC, which is what the mobile appliances use.

2) We will use flat piezoelectric discs and keep the components, such as the bridge diode small, and would implant the components on the actual sole of the shoe.
3) We will use multiple piezoelectric discs, conduct tests earlier in the test, and maximise the potential of the piezoelectric discs by inserting foam pushers on them so that the conversion of energy is more efficient, and use the actual sole of the shoe so that it can allow flexibility, while conserving energy productivity.

Equipment list:      
- Cheap/ Generic USB Power bank
- Piezoelectric Transducers (6x)
- 1N4007 Rectifier Diodes (4x)
- Hookup Wire (at least 12")
- Old Pair Of Shoes with soles present
- Contact Adhesive
- Hoop & Loop Fastener (Velcro)

Tools & Equipment:
- Digital Multimeter
- Multitool (w/ pliers)
- Rotary Tool/ Small Drill
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Optional:
- 100nF Mylar Capacitor (for testing)
- LED Indicators (for testing)
- Superglue (for fixing wires)
- Smartphone Sport Strap
- 5v Switching Regulator (w/ supercap)

Alternatives: (since not all can afford them)
- PowerBank > Old phone batteries + Recycled 5v Inverter
- Piezo Transducers > A pair of old & outdated earpiece (take out the sound piezo transducer from the earphones)
- Rotary tool > A Penknife
- Multitool > A pair of pliers will do
    
The independent variables:
1) The pressure applied on shoe while walking
2) Weight of the user
3) The foot structure of the user.
    
The dependent variables are:

The amount of electrical energy produced.

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