The world has always been galloping in the chariot of technological wonders, where change is constant.

Adding a feather in the cap of modern technological wonder babies, science has given birth to a robust mechanism called ‘WITRICITY’.

INTRODUCTION:

In this era of modernization, electricity has become the cup of life. A moment without electricity makes your thinking go dry. The major source of conventional form of electricity is through wires. The continuous research and development has brought forward a major breakthrough, which provides electricity without the medium of wires. This wonder baby is called Witricity.

There are certain small but very useful discoveries made in history, which changed the world for ever, Newton’s gravitational law, Watt’s steam engine, Thomson’s bulb and many more. But a renaissance occurred with the invention of Electromagnetic Waves by Maxwell. Sir Jagdish Chandra Bose successfully generated electromagnetic waves having wavelength in the range of 5mm to 25 mm. Thereafter an Italian scientist named Marconi succeeded in transmitting electromagnetic waves up to a distance of several miles.

And with this there started a new era called WIRELESS TECHNOLOGY. Today, as we can see the word ‘wireless’ is common in day – to – day life. Wireless communication has made the world smaller. Almost each and everything is wireless or cordless. Cordless mouse, cordless keyboard, satellite communication, mobiles, cordless microphones and headphones, wireless internet service i.e. WI-FI, etc. And these have definitely increased the standard of living.

Witricity is a coined term for wireless electricity, which was coined by the thinking brain of Dave Garding in the year 2005. The principle of wireless electricity transfers electricity to objects without the medium of wires. The system consists of two basic components called Witricity transmitter and Witricity receiver.

The principle of wireless electricity was initiated by Nikola Tesla in the later part of 19^th century, which was later capitalized by a MIT research team lead by Marin Soljačić in the year 2007. Nikola Tesla worked on the principle of electromagnetic waves, but could not result in the making of wireless electricity, whereas Marin Soljačić and his team worked on the principle of Magnetically Coupled Resonance, which gave birth to WITRICITY.

HISTORY:

In 1825 William Sturgeon invented the electromagnet, a conducting wire wrapped around an iron core. The principle of EM induction — that a changing magnetic field can induce an electrical current in an adjacent wire — was discovered by Michael Faraday in 1831. Combining these two discoveries, Nicholas Joseph Callan was the first to demonstrate the transmission and reception of electrical energy without wires. Callan’s 1836 induction coil apparatus consisted of two insulated coils — called the primary and secondary windings — both placed around a common iron core. A battery intermittently connected to the primary would ‘induce’ a voltage in the longer secondary causing a spark to jump across its free terminals.

In an induction coil or electrical transformer, which can have either an iron core or an air core, the transmission of energy takes place by simple electromagnetic coupling through a process known as mutual induction. With this method it is possible to transmit and receive energy over a considerable distance. However, to draw significant power in that way, the two inductors must be placed fairly close together.

If resonant coupling is used, where inductors are tuned to a mutual frequency, significant power may be transmitted over a range of many meters.

In 1864 James Clark Maxwell mathematically modeled the behavior of electromagnetic radiation. Some early work in the area of energy transmission via radio waves was done in 1888 by Heinrich Hertz who performed experiments that validated Maxwell’s mathematical model. Hertz’s apparatus for generating electromagnetic waves is generally acknowledged as the first radio transmitter. A few years later Guglielmo Marconi worked with a modified form of the Hertz-wave transmitter, the main improvement being the addition of an elevated conductor and a ground connection. Both of these elements can be traced back to the 1749 work of Benjamin Franklin and that of Mahlon Loomas in 1864.

Nikola Tesla also investigated radio transmission and reception but unlike Marconi, Tesla designed his own transmitter — one with power-processing capability some five orders-of-magnitude greater than those of its predecessors. He would use this same coupled-tuned-circuit oscillator to implement his conduction-based energy transmission method as well. Both of these no-cables methods employ a minimum of four tuned circuits, two at the transmitter and two at the receiver.

As wireless technologies were being developed during the early 1900s, researchers further investigated these different transmission methods. The goal was simply to generate an effect locally and detect it at a distance. Around the same time, efforts began to power more significant loads than the high-resistance sensitive devices that were being used to simply detect the received energy. At the St. Louis World’s Fair (1904), a prize was offered for a successful attempt to drive a 0.1 horsepower (75 W) air-ship motor by energy transmittedthrough space at a distance of least 100 feet (30 m).

Except for RFID tags, power transmission over room-sized or community-sized distances has not been widely implemented. Rightly or not, it has been assumed by some that any system for broadcasting energy to power electrical devices will have negative health implications. With focused beams of microwave radiation there are definite health and safety risks. Considering the hazards associated with powerful radiation, the physical alignment and targeting of devices to receive the energy beam is of particular concern. However with the use of resonant coupling, wavelengths produced are far lower making it no more dangerous than being exposed to radio waves.

INVENTORS OF WITRICITY:

The inventors of Witricity are the researchers from the team from Massachusetts Institute of Technology. They are the people who had coined the phrase of Witricity and this invention can change the way electricity is used today. With Witricity, the tangle of cables, plugs and charters that normally clutter homes can be rid of.
This team from MIT belonged to the Department of Physics, Department of Electrical Engineering and Computer Science and the Institute for Soldier Nanotechnologies. The members of this team were Andre Kurs, Aristeidis Karalis, Prof. Peter Fisher, Robert Moffat and Prof. John Joannopoulos. The leader of this team of researchers was Prof. Marin Soljačić.
It was Prof. Marin Soljačić who provided the inspiration for the experiment and invention of Witricity. It was while standing in the kitchen one night, that on staring at his mobile phone that he had thought it would be nice if his mobile phone would take care of its own charging instead of him having to periodically charge it.
He then tried out his experiment using two coils of copper, where one was connected to a receiver, and the other to a transmitter. With the help of these two coils of copper, the inventors of Witricity managed to transmit power across seven feet through the air to instantly light up a light bulb.
Though Witricity worked only distances up till 9 feet at its inception, the inventors believed that it was possible to charge a battery that was located at a distance of a few yards from the power source that was connected to the receiving coil. They state that it would be sufficient to place a source in each room to provide power to the whole house.

ABOUT MARIN SOLJACIC:

Marin Soljačić was the leader of the team of researches from MIT who had found out a means of transmitting electricity to electrical gadgets without using any wires. He was basically an Assistant Professor of Physics since September 2005 who has a BsE degree in physics and electrical engineering from MIT in the year 1996. After this, he had earned his PhD in physics from the Princeton University in the year 2000.It was in September 2000 that he was named an MIT Pappalardo Fellow in Physics and in the year 2003, he was appointed the Principal Research Scientist in the for the Research Laboratory of Electronics at MIT in the year 2003. He was also awarded the Adolph Lomb medal from the Optical Society of America in the year 2005.
It was basically his interests in exploring new and exciting concepts in physical phenomena that led him to experiment with the concept of wireless electricity. With this, he said that Witricity would eventually replace power cables in the same way mobile and cordless phones have replaced landlines today.
Professor Soljačić basically turned to the concept of resonance to create Witricity where there is efficient transmission of energy between the two objects that tend to resonate at the same frequency. The typical Witricity system has two copper coils where one sends power and the other receives it. This concept worked efficiently and automatically where there is no necessity of having a clear line of sight in between the transmitter and electronic appliance. All that is needed for Witricity is a source of wireless power which charges automatically without needing any plugging in.

WITRICITY A BOON:

Modern science has blessed us with a concept called Witricity, which has a bright future of providing electricity without wires.

Witricity enables the transmission of electricity without the mediums of cables or batteries.

An area covered by the concept of Witricity can avoid the discomfort cost by wires and cables and hence enhance the standard of living. Witricity avoids a lot of time consumption of charging and buying new batteries for your electrical gadgets.

Imagine a world without wires and cables. It will help us provide utilization of space for many better things. Witricity has a bright future with many advantages in terms of weight, convenience and portability of electrical appliances.

The concept of Witricity has a wide range of potential applications. Some of these applications include the powering of cell phones, house hold robots, laptops, and other devices which normally run with batteries or plugging of wires. A few years from now is expected to see the applications of Witricity materialize by making the necessary modifications.

Witricity can be applied on gadgets that are in close proximity, wherein the gadgets charge automatically without being plugged in. The application of Witricity can come in use where gadgets run through batteries or electrical connections.

WITRICITY POWER APPLICATIONS:

Researchers from the Massachusetts Institute of Technology have devised a means of transferring electricity without using any wires. They have dubbed this technology as Witricity and have declared that there are many potential applications for it. Some of these potential applications include the powering of cell phones, household robots, laptops and other devices that normally run with the help of batteries or with plugging in of wires.
As Witricity is in the developmental stage, lots of work is still to be done in improving it as the device used for their research disclosed that Witricity power applications operate at only 40% efficiency. The potential applications of Witricity are expected to materialize in the new future, of say a few years’ time, after the necessary modifications are made to them.
These Witricity applications are expected to work on the gadgets that are in close proximity to a source of wireless power wherein the gadget charges automatically without necessarily having to get plugged in. There are no limitations in Witricity power applications where anything and everything that used to run with batteries or electrical connections can be used using Witricity.
Just imagine, the future Witricity power applications permit you to use wireless energy, without having to replace or recharge batteries. There will be no need of getting rid of these batteries either or of remembering to recharge batteries periodically. In addition to this, with Witricity, there is no need of plugging in any wires and plugs and thus face a mess of wires.

FEASIBILITY OF WITRICITY:

A question may arise that “Is it really possible to transmit electricity without any wires?”SIR NIKOLAS TESLA discovered this on observing the common phenomenon of lightning.As we know that, when two clouds strikes with each other a large spark is produced which we call lightening.

If lightning can connect the earth without the support of any medium, why not electricity?

PRECAUTIONS! :

In order to produce a wireless power transmission it is necessary to take certain precautions as mentioned below:

• Witricity should not harm any living organism.
• Witricity should not disturb any natural phenomenon.
• Transmission of wireless electricity should not match with the frequency of any existing electromagnetic waves.
• Witricity should work even when the line of sight between the receiver and transmitter is blocked.

MIT RESEARCHER's EXPERIMENT:

Taking into considerations all the above points and precautions the researchers of Massachusetts Institute of Technology, USA successfully produced wireless electricity for the first time in the year 2007.

Principle:

Witricity works on the principle of Magnetically Coupled Resonance. As underlined the whole term is coined from two phenomenons, viz. Magnetic Coupling and Electrical Resonance.

Electrical Resonance:

It takes place when the impedance between the input and output is minimum, ideally zero and when the transfer functions of both the circuits are equal.

Resonance of a circuit involving capacitors and inductors occurs because, the collapsing magnetic field of the inductor generates an electric current in its windings which charges a capacitor. And then discharging of a capacitor provides an electric current that builds the magnetic field in the inductor and the process is repeated continually.

Since the impedance between the input and output circuit should be ideally zero for a perfect resonance, the inductive reactance and the capacitive reactance is equal in magnitude.

Therefore, ωL = 1/ωc

ω = 1/√LC

Where ω = 2πf, in which f is resonant frequency.

Magnetic Coupling:

In electronics, magnetic or inductive coupling refers to the transfer of energy from one circuit component to the other through a shared magnetic field. According to Faraday’s law of Electromagnetic Induction, change in flux in one circuit component induces emf in another component. The two components may be physically contained in a single unit, as in primary and secondary windings of a transformer, or may be separated as in antennas on a transmitters and receivers.

The resonance obtained using this principle is termed as Magnetically Coupled Resonance.

Examples of Resonance:

A child on a swing is a good example of this. A swing is a type of mechanical resonance, so only when the child pumps his legs at the natural frequency of the swing is he able to impart substantial energy.

Another example involves acoustic resonances: Imagine a room with 100 identical wine glasses, each filled with wine up to a different level, so they all have different resonant frequencies. If an opera singer sings a sufficiently loud single note inside the room, a glass of the corresponding frequency might accumulate sufficient energy to even explode, while not influencing the other glasses. In any system of coupled resonators there often exists a so-called “strongly coupled” regime of operations. If one ensures to operate in that regime in a given system, the energy transfer can be very efficient.

While these considerations are universal, applying to all kinds of resonances (e.g., acoustic, mechanical, electromagnetic, etc.), the MIT team focused on one particular type: Magnetically Coupled Resonators.

The investigated design consists of two copper coils, each consisting of a self-resonant system. One of the coils, attached to the power source, is the sending unit. Instead of irradiating the environment with electromagnetic waves, it fills the space around it with a non-radiative magnetic field oscillating at MHz frequencies. The working of Witricity oscillates around 10 Mhz. The non-radiative field mediates the power exchange with the other coil (the receiving unit), which is specially designed to resonate with the field. The resonant nature of the process ensures the strong interaction between the sending unit and the receiving unit, while the interaction with the rest of the environment is weak. As shown in a figure below the setup which consists of two capacitively loaded copper coils, each of 60 centimeter in diameter, powered a 60 watt light bulb from a power source that was two meters away at roughly 40% efficiency.

The below diagram highlights that Witricity can pass through even if there is an obstruction of any medium.

It does not affect living organisms because the magnetic field interacts very weakly with biological organisms.

Magnetic coupling is particularly suitable for everyday applications because most common materials interact very weakly with magnetic fields, so interactions with extraneous environmental objects are suppressed even further.

“The fact that magnetic fields interact so weakly with biological organisms is also important for safety considerations,” Kurs, a graduate student in physics, points out.

The crucial advantage of using the non-radiative field lies in the fact that most of the power not picked up by the receiving coil remains bound to the vicinity of the sending unit, instead of being radiated into the environment and lost.

SCHEMATIC OF EXPERIMENTAL SETUP:

A is a single copper loop of radius 25cm which supplies the power to the source S.

D is the device consuming power.

B is the loop of wire attached to the loop.

K_S and K_D are the coefficient of coupling of source and device respectively.

K is the resultant coefficient of coupling.

Coefficient of Coupling (K) is the amount of coupling that takes place between the two windings.

WORKING OF WITRICITY:

CONCLUSION:

Advantages of witricity will be a blessing by getting fed of the head-aches of recharging the electrical gadgets. There will be a time when shopkeepers will laugh at us when we ask for chargers or batteries.

Hence it’s time to say

“GOOD-BYE WIRES”.