Piezoelectricity: The Way To Revolutionize SmartWatch Efficiency

How to use piezoelectricity to save battery percentage of a smart watch.
Adithya Rajeev
Grade 7

Problem

I frequently noticed my dad saying that his watch drains out in battery and I have heard many people say  the same thing too. I then decided that I have to make it more efficient and in an ecofriendly way to prolong the battery life.

Method

The basic concept of this project is to prolong the battery life of smart watches by using piezoelectricity concept. An average watch has a battery life of around 18 hours, and within modern amenities, the battery life of smart watches do not last long. Since wearable technology like smart watches involves lot of hand movement, using a piezoelectric disc, with amplification would be able to increase the charge by a certain amount. This means we can convert the physical hand movement for charging the watches using piezoelectric discs. This would then eliminate the need for constant charging, and conserving electricity. I will connect the piezo elelctric disc to a diode and then to the voltage multiplier which will be connected to the battery which is what powers the whole watch. 

Research

How would I implement my project?

The most important components are the battery , piezoelectric disc and charging circuit.

There would be some safety concerns. The charge coming from the piezoelectric disc is too low to charge a battery and we would need to amplify the electricity. For this reason I decided to use a voltage multiplier which as its name suggests can multiply the voltage enough to power our battery.

But we would need to put a diode as charges can reverse from the piezoelectric disc and could explode or start a small fire! A charging circuit would also be connected because our goal is not to charge the smartwatch permanently but make it more efficient.

At last the end leads or the output wires of the battery would be able to power the rest of the components making up the smartwatch.

How does it work and how do the components contribute?

The charge produced from the piezoelectric material travels through the wire to the diode which prevents the piezoelectric material from failing. Then it travels through the voltage multiplier and charges the battery. The charging circuit when plugged in also powers the battery when low. Then the battery would store the electricity and gives it off slowly.

What are lithium ion batteries ?


We are going to use a special type of rechargeable battery known as a “lithium ion battery”. They are lightweight, fast charging and temperature tolerant.

A lithium battery has basic parts known as “cathode, anode, and electrolyte. Cathode is the positive electrode, anode which is the negative electrode and the electrolyte is a chemical compound which helps the charges flow through the electrodes. The most commonly used material for cathode is lithium cobalt oxide cathode and the most commonly used material for the anode is graphite anode.

When plugged in, electrons start to enter the battery and the lithium atoms start to meet up with them at the anode and when you stop plugging it in the electrons start losing their charge which makes the electron to moves to the cathode which provides charge and the lithium atom meet the electron again and they move back to the anode as they lose charge and it repeats again until there is no more charge left.

How does a voltage multiplier work?

A voltage multiplier works by using a sophisticated circuit board and a series of capacitors to multiply the voltage.

How does a diode work?

A diode is made of silicone and contains semiconductors (a semi conductor is a conductive material and has a insulator.) / impurities known as p on one side a n on the other. The p impurity has more space for the charge to move and so the charges move from n to p and travels through to the device. But when charge are not given the correct way the p semiconductor would not let the charges flow as there is not enough space in N side.


How does a charging circuit work?

A charging circuit is a circuit board that is run through resistors and other components to charge each cell of a battery.

Why did I choose a piezoelectric disc?

I choose it as its the most reliable material that can be used as it can be soldered and can be manipulated.

 

What are smart watches?

A smart watch as its name suggests is a watch that has a brain of a sort that can process and give information. They can also track your health steps and some are able to connect with your phone which is useful as you can take calls and view messages.

There are two types of smart watches: “daily use smart watch" and the “specific use smart watch”. The main difference between them are that the daily use smartwatches are used for daily proposes and the specific use smart watch is used for a specific activity or purpose.

What do they consist of?

They mainly consist of a (computer / brain), battery and sensors, and sometimes camera. 

What I chose as the solution.

The way I decided to make it more efficient is by using a special material called piezoelectric material which can produce electricity when a mechanical or compressive stress is applied and this can deliver charge the battery every once in a while.

Solution elaboration

If we plug the piezoelectric material to the battery it can feed a small voltage (when force is applied) which acts as a part time charger.


What is piezoelectricity?

Piezoelectricity is a form of which when a force is applied the material produces a charge. In other words when you have a piezoelectric material it generates electricity when a compressive or mechanical force is applied which can be used to operate or function a device or object.



How does it work?

When we look at a quartz crystal (quartz crystal is a piezoelectric material) From a frame of reference we can comprehend it as a hexagonal shape and the edges of the hexagon contains an oxygen atom and a silicon atom which share one electron.

The oxygen atom is more electronegative because of electronegativity (electronegativity is a scientific principle) which results in the electron being closer to the oxygen atom. The silicon atom have a positive charge which creates a dipole/ center of charge. When a compressive or mechanical stress is applied the charges do not coincide any more and this is called polarization.


This results in the generation of an electric field between the two charges. This current is created all over the material. So why don’t we use it to make smart watches more efficient by permanently plugging the piezoelectric material onto the battery.

What are some piezoelectric materials?Piezoelectricity only happens on some materials and they are barium titanate, lead zirconate titanate and quartz. There are many more materials that produce piezoelectricity but these are the main materials which are commonly used.

Data

Info of piezoelelctric disc.

A piezoelelctric disc that is  70mm can produce a max of 3.7 volts

A piezoelectric disc that is 150mm can produce a max of 10 volts

At last a piezoelelctric disc that is 200mm can produce a max of 20 volts or more.

 

 

data annalisis.

I noticed that the piezoelectric disc is working as when I applied a stress it lit an led which means it was able to produce electricity.

Conclusion

Since smart watches are not efficient in conserving their battery power I had come up with the solution of using piezoelectricity effect to convert the kinetic energy to electric charge capable of charging the smart watches. I hypothesized that piezoelectricity would be the best option as for its capabilities and manageability.



The model also manifests how it is possible to accomplish this device in a real world situation and industrial properties to further advance our knowledge of piezoelectricity, and relation between piezoelectricity and other technologies.

My hypothesis was correct as piezoelectric disc was a safe and fabulous technology that can be used for the project.

Acknowledgement

I acknowledge my science teacher for giving e this opertunity and supporting me to compleat my project.

I acknowledge my ELA teacher for her motivation and my school judges for the amazing support.

I acknowledge my parents and friends for the support they have offered me.