Did
you know that you can produce electricity by just walking? Here's a
little science experiment that will show you a little secret on making
insoles that can charge USB devices! The challenge is to make a slip-on
insole that can produce enough electricity to charge batteries/ USB
devices.
Concept Behind The Project:
Piezoelectricity was present ever since mid-18th century. Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics in response to applied mechanical stress. This sounds familiar! Yes they do, you can actually find those piezo elements in your old/ outdated earphones from the 90's.
Why Not Use Dynamos?
As much as possible, I tried to avoid using dynamos. Yes dynamos produce more electricity but it will feel like you've stuffed a rock in your shoe. Don't forget dynamos will create a lot of noise.
Any Practical Uses?
As funny as it sounds, charging a phone with your shoe isn't really joke. Who knows maybe someday shoe companies like Nike could use these insole generators to power fitness chips (inside shoes) that would sync to your phone wirelessly. This way, you don't have to charge your smart-shoes just to sync them with your phone.
Disclaimer: This is just a little science experiment. It's not a product just yet and I can't assure you'll get the same results
Concept Behind The Project:
Piezoelectricity was present ever since mid-18th century. Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics in response to applied mechanical stress. This sounds familiar! Yes they do, you can actually find those piezo elements in your old/ outdated earphones from the 90's.
Why Not Use Dynamos?
As much as possible, I tried to avoid using dynamos. Yes dynamos produce more electricity but it will feel like you've stuffed a rock in your shoe. Don't forget dynamos will create a lot of noise.
Any Practical Uses?
As funny as it sounds, charging a phone with your shoe isn't really joke. Who knows maybe someday shoe companies like Nike could use these insole generators to power fitness chips (inside shoes) that would sync to your phone wirelessly. This way, you don't have to charge your smart-shoes just to sync them with your phone.
Disclaimer: This is just a little science experiment. It's not a product just yet and I can't assure you'll get the same results
A Question That Bothers Me A Lot:
Why not use traditional renewable energy sources? Yes I know piezoelectricty is not as well develop as of those solar powered devices but as a curious being, I am open to discovering potential energy sources. Yes, footwear generators may sound crazy and ridiculous but there's more than what meets the eye! These thin insole generators have enough power to supply low current devices.
My goal is to find a new source of renewable energy, something that does not depend on wind, water or sunlight. I did some random research and I came through tons of eco-energy production articles. I told myself, if I'll go with another solar/ wind experiment, there won't be enough innovation by just remaking a project from the internet. Like all scientists, I had to think out of the box.
The questions are:
- Does it have enough power to supply electricity for low consumption modules?
- Will it produce enough power to charge USB devices?
- Can it reach the USB standards?
- Can it power a series of LEDs?
Future Practical Applications:
- Supply on-board/ independent power for smarts shoes and clothing.
- Aid outdoorsmen/ hikers, with GPS tracking shoes,in their journey into the vast wilderness.
- Great for areas where electricity is scarce. - Self-powering rescue chips in shoes.
Scientific Research:
The project is be accomplished by using piezoelectric materials. Piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an alternating current voltage when actuated.Certain ceramics, Rochelle salts, and various other solids exhibit this effect. For example, (Pb[ZrxTi1−x]O3 where,0≤x≤1), also called PZT, will generate measurable electricity when their structure is deformed by about 0.1% of the original dimension(International AAAI Conference on Social Media and Weblogs, 2012). In this project, the generated electricity on a specific time will be recorded and determine if it would be enough to completely charge a Li-ion battery or a high capacity capacitor.
The project is be accomplished by using piezoelectric materials. Piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an alternating current voltage when actuated.Certain ceramics, Rochelle salts, and various other solids exhibit this effect. For example, (Pb[ZrxTi1−x]O3 where,0≤x≤1), also called PZT, will generate measurable electricity when their structure is deformed by about 0.1% of the original dimension(International AAAI Conference on Social Media and Weblogs, 2012). In this project, the generated electricity on a specific time will be recorded and determine if it would be enough to completely charge a Li-ion battery or a high capacity capacitor.
The piezoelectric effect, by which a material generates an electric potential in response to a temperature change, was studied by Carl Linnaeus and Franz Aepinus in the mid-18th century. Drawing on this knowledge, both René Just Haüy and Antoine César Becquerel posited a relationship between mechanical stress and electric charge; however, experiments by both proved inconclusive. The first demonstration of the direct piezoelectric effect was in 1880 by the brothers Pierre Curie and Jacques Curie. They combined their knowledge of pyroelectricity with their understanding of the underlying crystal structures that gave rise to pyroelectricity to predict crystal behavior, and demonstrated the effect using crystals of tourmaline, quartz,topaz, cane sugar, and Rochelle salt (sodium potassium tartrate tetrahydrate). Quartz and Rochelle salt exhibited the most piezoelectricity.
A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated) The Curies, however, did not predict the converse piezoelectric effect. The converse effect was mathematically deduced from fundamental thermodynamic principles by Gabriel Lippmann in 1881. The Curies immediately confirmed the existence of the converse effect, and went on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations in piezoelectric crystals. For the next few decades, piezoelectricity remained something of a laboratory curiosity. More work was done to explore and define the crystal structures that exhibited piezoelectricity. This culminated in 1910 with the publication of Woldemar Voigt's Lehrbuch der Kristallphysik (Textbook on Crystal Physics), which described the 20 natural crystal classes capable of piezoelectricity, and rigorously defined the piezoelectric constants using tensor analysis.
Results:
An Arduino development board was used to establish a simple oscillocope setup. It was plugged to the computer, the built-in TTL was used to establish serial communication between the Arduino and PC. A sketch was uploaded, using the Arduino IDE, to monitor the Analog pin where the insole generator was connected. A separate program, called "processing 2.0", was used to monitor the ripple given off by the converted AC►DC output of the generator.
Conclusion/ Report:
The current results showed that the product has potential to charge lithium batteries. Though there are room for improvements, it showed positive signs for it to be further developed. Based from the results, the insole generator has enough power to supply voltage for low powered circuits such as MCUs (Micro Controller Units - ex. ATtiny) and TTL Bluetooth transmitters. I can now say that the product is ready for production and is highly usable for smart clothing/ shoes although charging USB devices won't suffice just yet.
FURTHER PLANS:
If a whole insole was to be made with a thin flexible sheet of metal and glazed with piezoelectric elements (back-to-back) then it would probably produce enough power to qualify within the USB standards. A standardized opensource 3D printed design will certainly introduce a new energy-production concept to the DIY community. When everyone has access to an opensource project great ideas flourish!
Why not use traditional renewable energy sources? Yes I know piezoelectricty is not as well develop as of those solar powered devices but as a curious being, I am open to discovering potential energy sources. Yes, footwear generators may sound crazy and ridiculous but there's more than what meets the eye! These thin insole generators have enough power to supply low current devices.
My goal is to find a new source of renewable energy, something that does not depend on wind, water or sunlight. I did some random research and I came through tons of eco-energy production articles. I told myself, if I'll go with another solar/ wind experiment, there won't be enough innovation by just remaking a project from the internet. Like all scientists, I had to think out of the box.
The questions are:
- Does it have enough power to supply electricity for low consumption modules?
- Will it produce enough power to charge USB devices?
- Can it reach the USB standards?
- Can it power a series of LEDs?
Future Practical Applications:
- Supply on-board/ independent power for smarts shoes and clothing.
- Aid outdoorsmen/ hikers, with GPS tracking shoes,in their journey into the vast wilderness.
- Great for areas where electricity is scarce. - Self-powering rescue chips in shoes.
Scientific Research:
The project is be accomplished by using piezoelectric materials. Piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an alternating current voltage when actuated.Certain ceramics, Rochelle salts, and various other solids exhibit this effect. For example, (Pb[ZrxTi1−x]O3 where,0≤x≤1), also called PZT, will generate measurable electricity when their structure is deformed by about 0.1% of the original dimension(International AAAI Conference on Social Media and Weblogs, 2012). In this project, the generated electricity on a specific time will be recorded and determine if it would be enough to completely charge a Li-ion battery or a high capacity capacitor.
The project is be accomplished by using piezoelectric materials. Piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an alternating current voltage when actuated.Certain ceramics, Rochelle salts, and various other solids exhibit this effect. For example, (Pb[ZrxTi1−x]O3 where,0≤x≤1), also called PZT, will generate measurable electricity when their structure is deformed by about 0.1% of the original dimension(International AAAI Conference on Social Media and Weblogs, 2012). In this project, the generated electricity on a specific time will be recorded and determine if it would be enough to completely charge a Li-ion battery or a high capacity capacitor.
The piezoelectric effect, by which a material generates an electric potential in response to a temperature change, was studied by Carl Linnaeus and Franz Aepinus in the mid-18th century. Drawing on this knowledge, both René Just Haüy and Antoine César Becquerel posited a relationship between mechanical stress and electric charge; however, experiments by both proved inconclusive. The first demonstration of the direct piezoelectric effect was in 1880 by the brothers Pierre Curie and Jacques Curie. They combined their knowledge of pyroelectricity with their understanding of the underlying crystal structures that gave rise to pyroelectricity to predict crystal behavior, and demonstrated the effect using crystals of tourmaline, quartz,topaz, cane sugar, and Rochelle salt (sodium potassium tartrate tetrahydrate). Quartz and Rochelle salt exhibited the most piezoelectricity.
A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated) The Curies, however, did not predict the converse piezoelectric effect. The converse effect was mathematically deduced from fundamental thermodynamic principles by Gabriel Lippmann in 1881. The Curies immediately confirmed the existence of the converse effect, and went on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations in piezoelectric crystals. For the next few decades, piezoelectricity remained something of a laboratory curiosity. More work was done to explore and define the crystal structures that exhibited piezoelectricity. This culminated in 1910 with the publication of Woldemar Voigt's Lehrbuch der Kristallphysik (Textbook on Crystal Physics), which described the 20 natural crystal classes capable of piezoelectricity, and rigorously defined the piezoelectric constants using tensor analysis.
Results:
An Arduino development board was used to establish a simple oscillocope setup. It was plugged to the computer, the built-in TTL was used to establish serial communication between the Arduino and PC. A sketch was uploaded, using the Arduino IDE, to monitor the Analog pin where the insole generator was connected. A separate program, called "processing 2.0", was used to monitor the ripple given off by the converted AC►DC output of the generator.
Conclusion/ Report:
The current results showed that the product has potential to charge lithium batteries. Though there are room for improvements, it showed positive signs for it to be further developed. Based from the results, the insole generator has enough power to supply voltage for low powered circuits such as MCUs (Micro Controller Units - ex. ATtiny) and TTL Bluetooth transmitters. I can now say that the product is ready for production and is highly usable for smart clothing/ shoes although charging USB devices won't suffice just yet.
FURTHER PLANS:
If a whole insole was to be made with a thin flexible sheet of metal and glazed with piezoelectric elements (back-to-back) then it would probably produce enough power to qualify within the USB standards. A standardized opensource 3D printed design will certainly introduce a new energy-production concept to the DIY community. When everyone has access to an opensource project great ideas flourish!
- Piezo Electricity - is the ability of certain materials to generate an AC (alternating current) voltage when subjected to mechanical stress or vibration, or to vibrate when subjected to an AC voltage, or both. The most common piezoelectric material is quartz. Certain ceramics, Rochelle salts, and various other solids also exhibit this effect.
- Actuated - cause a machine to operate/ work/ generate.
- Piezo - shorthand for piezoelectric
- AC Current - the flow of electric charge periodically reverses direction. Piezo elements produce these currents.
- DC Current - the flow of electric charge is only in one direction. Batteries produce these currents
- Bridge Diode - usually is composed of four rectifier diodes that filter AC currents and turn them into DC currents.
- Piezo Disc/ Element/ Transducer - they are all the same, it refers to the discrete component that produces current when actuated. They are also known as ceramic transducers and are usually found in outdated pairs of earpiece.
Needed Materials
Parts/ Materials:
- Cheap/ Generic USB Powerbank
- Piezoelectric Transducers (6x)
- 1N4007 Rectifier Diodes (4x)
- Hookup Wire (at least 12")
- Old Pair Of Shoes
- Contact Adhesive
Tools & Equipment:
- Digital Multimeter
- Multitool (w/ pliers)
- Rotary Tool
Optional materuals:
- 100nF Mylar Capacitor (for testing)
- Hoop & Loop Fastener (Velcro)
- 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
- Peizo Transducers > A pair of old & outdated earpiece
- Rotary tool > Hot Nail (for melting plastic)
- Multitool > A pair of pliers will do
- Cheap/ Generic USB Powerbank
- Piezoelectric Transducers (6x)
- 1N4007 Rectifier Diodes (4x)
- Hookup Wire (at least 12")
- Old Pair Of Shoes
- Contact Adhesive
Tools & Equipment:
- Digital Multimeter
- Multitool (w/ pliers)
- Rotary Tool
Optional materuals:
- 100nF Mylar Capacitor (for testing)
- Hoop & Loop Fastener (Velcro)
- 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
- Peizo Transducers > A pair of old & outdated earpiece
- Rotary tool > Hot Nail (for melting plastic)
- Multitool > A pair of pliers will do
Get
the size and shape of your shoe's insole then get a pair of heavy-duty
shears/ snips and carefully cut the PVC material. The plate will act as
the primary mount of the piezoelectric discs/ elements.
Remember: Thickness matter, you need at least 2-5mm. If your material is too thick, the piezo elements will break due to too much flexing. If your material is too thin, the piezo element won't bend at all thus converting less power.
Remember: Thickness matter, you need at least 2-5mm. If your material is too thick, the piezo elements will break due to too much flexing. If your material is too thin, the piezo element won't bend at all thus converting less power.
Find And Cut An Ideal Material (Sheet/ Plate)
Now surround the PVC plate with three piezo discs. How do I know where the center is? The "center" that I'm referring to is area where all the pressure is withdrawn by your foot, your sole.
After getting a fix preview of the setup, get a pencil and trace the piezo discs. Finally use your compass to draw smaller circles, about 2mm smaller in radius. The 2mm spacing will act as your margin.
Were did you get the PVC material?
PVC materials are all around us. You can find them in your local hardware store but in the form of pipes. I got mine from our excess supply of PVC pipes when our house was built. Recycling means free $$$ for me! :)
Grinding Holes On PVC Pads
In
this step, grinding is required to bore/ drill round holes. Since I
don't have large drill bits (as large as the marked area), I've thought
of way to cleanly cut the holes and that's by using my handy rotary
tool.
If you don't have a rotary tool, you can still cleanly cut the plastic by doing it "the old fashioned way", by heating an iron nail and melting the plastic.
If you don't have a rotary tool, you can still cleanly cut the plastic by doing it "the old fashioned way", by heating an iron nail and melting the plastic.
Gluing The Piezoelectric Elements
These
piezo discs must endure a lot of flexing since you'll be stepping on
them repeatedly! Never use superglue, if you do, the moment you step on
your insole the piezo discs will snap off the PVC pad. Instead, use
those quick setting "contact adhesives". Their rubbery characteristic
makes them ideal for this project since they stretch whenever they are
bent.
Soldering The Piezos Together
Solder
all piezo elements together in parallel. Don't solder them in series
because you'll need more current than voltage and those piezoelectric
discs will cancel each other's power output when not actuated at the
same time.
Piezo elements produce AC currents. Unlike DC currents, you can't just tap in the line. since AC currents are always alternating polarities. Just like power generators, whether it may be solar or petrol, you can't just tap directly to the powerlines without aligning the AC wave's phase otherwise the generator will cancel each other. (Ex. Negative meets Positive - Positive meets Negative). This infers that parallel works best for our project.
Improvements:
Through this process of experimentation, I've realized that even if they are hooked in parallel the piezoelectric elements can still cancel each other's output off (when not actuated simultaneously). This leads to conclusion that you'll need to add one bridge diode per piezo element/ disc.
Piezo elements produce AC currents. Unlike DC currents, you can't just tap in the line. since AC currents are always alternating polarities. Just like power generators, whether it may be solar or petrol, you can't just tap directly to the powerlines without aligning the AC wave's phase otherwise the generator will cancel each other. (Ex. Negative meets Positive - Positive meets Negative). This infers that parallel works best for our project.
Improvements:
Through this process of experimentation, I've realized that even if they are hooked in parallel the piezoelectric elements can still cancel each other's output off (when not actuated simultaneously). This leads to conclusion that you'll need to add one bridge diode per piezo element/ disc.
Building A Bridge Diode
Peizoelectric
elements produce AC when subjected to mechanical stress. Unfortunately,
USB devices need DC and not-AC. A bridge diode is required to filter
and convert AC to DC. 
Schematic:
Just follow the schematic diagram above. Solder the peizo discs to your bridge diode. Remember AC has no polarity, you can invert the wires either way. The load (shown as a resistor) represents your appliance.
Recycling:
CFL bulbs contain electronic ballasts, each ballast contains at least six to eight rectifier diodes. Those diodes are compatible with our project. Please be careful in disassembling CFL bulbs, I'm not liable if any of you get injured.
Adding Foams Pushers
Now
glue small a small piece of foam on the very center of each piezo disc.
These foams will act as pushers. These foams will squeeze the piezo
discs inwards (like sandwitches) while walking.Observation And Testing
Finally,
we are going to test the validity of or theory. Start by getting a
digital-tester and switch it to the 2 digit DC range. Remember, piezo
elements produce a short burst of current the moment you push them so
adding a 100nF capacitor should make the readings much more readable.
My volt meter displayed:
Pressing By Hand = 15.03 volts (2mA)
Walking By Foot = 18.53 volts (5mA)
Running By Foot = 27.89 volts (11mA)
My volt meter displayed:
Pressing By Hand = 15.03 volts (2mA)
Walking By Foot = 18.53 volts (5mA)
Running By Foot = 27.89 volts (11mA)
Adding A Powerbank + Soldering
The
insole generator peaks a voltage of 28 volts, the current may be small
but the voltage is enough to damage the powebank's 5v charger
(circuitry). I won't be using the 7805 since it's quite old and
inefficient. Right now, my insole generator is soldered directly to my
powerbank's lithium battery. It works but it's not completely not safe.
This is just a prototype so expect another Instructable tutorial/
write-up next week.
Future Prototypes - Developing Better Ones
abiola.johnson@outlook.com
theyoungengineerzz@gmail.com
WhatsApp +234-8079593532
