wireless_magnetic_inductiveWhen Guglielmo Marconi was awarded a patent for the wireless telegraph in the 1800s, the dream of wireless communications became a reality. That led to the birth of radio over the last century, we’ve discovered how to put electromagnetic waves to work for us, doing everything from transmitting our voices across continents to cooking our food to building weapons.  Because radio frequency (RF) travel through the air, and can be transmitted and received via antennas, they can be used to carry data short or long distances without wires.

Wireless networking is old hat by now. Everybody uses Wi-Fi and 3G/4G to transmit and receive data – despite the inherent dangers that I discussed in a previous blog post. Wireless keyboards and mice have become the new standard for desktop computing; in fact, it’s becoming a rare sight to see input peripherals connected via cables. Bluetooth headphones are increasingly popular for listening to music or holding hands-free conversations on our cell phones.

It’s no wonder everybody loves cutting the cord. The mass of cables behind the desk has always been the curse of computer users – they collect dust and somehow twist themselves into dozens of knots without any human intervention. Extricating your head and hair from an entanglement of wires running to a phone or MP3 player is not a pleasant experience. Wireless technologies greatly reduce the hassle factor of using electronic devices.

Radio transmission, like so many other wonders of our 21st century lives, is dependent on electricity. The Holy Grail of wireless has always been the delivery of electrical power itself without power lines. We’ve begun to see an example of that in the real world with the advent of “wireless chargers” for cell phones, although the idea has been around for at least a couple of decades.

This type of charging is technically called magnetic inductive charging and it uses electromagnetism to transfer energy between the charging station or pad and the phone or other device. Wireless chargers are available for many different phones and devices. Inductive charging uses an induction coil to create an electromagnetic field, in comparison to conductive wireless charging, which uses a charging board with a conductor to transfer energy (such as a sleeve for a cell phone).

What if you could power your whole house without wires?  What if you didn’t have to plug in your vacuum cleaner, your hair dryer, or your TV to use them? What if a light bulb could sit in the middle of the room and glow without being screwed into a lamp that’s plugged into the wall?

I hear you saying, “We already have that. It’s called battery-operated devices.”  True enough – and batteries are a wonderful invention that make our current mobile society possible – but today’s batteries have a fatal flaw: they run down. They often run down very quickly, and then you have to either replace them with new batteries or recharge them, rendering your device far less mobile while the charging takes place.

In fact, battery limitations pose one of the biggest challenges to the makers of mobile devices. And “mobile device” no longer means just small pocketable electronics, as more and more cars are built to run on electricity instead of gasoline. There are all sorts of ideas on the drawing board for solving this problem. Some companies have attempted to create batteries for phones and laptops that run on solar power. A company named uBeam raised money in 2012 to work on the development of wireless charging based on piezoelectricity, which is a charge created by the vibrations in certain crystals, but the company’s two founders got embroiled in a lawsuit and we haven’t heard much from the company since.

Now another new company is touting a technology called magnetic resonance that aims to solve the problem. It’s a form of magnetic induction that creates an electromagnetic field in an area, such as your home, which could power your devices and appliances that are within the field and recharge their batteries continuously, without you ever having to hook it up to a charger or lay it on a pad or even think about charging it.  Of course, the field generator itself still needs power, but we’re talking about plugging just one device into the wall instead of dozens. For a technical discussion of the difference between magnetic induction (MI) and magnetic resonance (MR), see this PDF.

The startup in question, called WiTricity, is working on the development of the MR technology, and envisions a day when we will no longer need 10 wall outlets in every room with a power strip plugged into each one. Its spokesperson hopes to expand this to medical devices, making it far less invasive to recharge the batteries in implanted devices such as pacemakers and ICDs (implantable cardiac defibrillators).

The company uses magnetic resonators that can transfer energy over relatively long distances in comparison to induction pads used for charging cell phones – up to several meters. The magnetic field can extend through and around obstacles that are between the power source and the capture device (including most common non-metal wall materials) so a direct line-of-sight isn’t necessary. A more detailed explanation of how the WiTricity devices work is available on their web site.

According to the WiTricity web site, the technology will be easy to embed in OEM products and can handle energy transfers up to the multiple kilowatt level. It will work both with devices that will always be within range of the power source (such as light bulbs or other fixed devices in a home) and as a means of recharging more mobile devices with rechargeable batteries.

Wireless electricity could have a profound effect on how electronic devices are designed and used. It could eliminate the need for removable batteries altogether. Imagine never having to hunt through your utility room drawer for a couple of AAA batteries when the TV remote dies, only to find four packs of C’s, a pack of D’s and a handful of 9 volts. Wouldn’t it be nice to never open up the battery compartment of a gadget you haven’t used in a while to find leaked acid corrosion because you forgot to remove the batteries?

Of course, we can expect that there will be controversy over the safety of such a technology, just as there has been concerning cell phone towers, Wi-Fi access points, microwave ovens  and even the power lines that span the countryside.  Any new technology generates fear, and all of these electromagnetic waves are, after all, a form of radiation. We know that exposure to rays at the high end of the electromagnetic spectrum, such as gamma rays and X-rays, and even the ultraviolet rays emitted by the sun, can be harmful to human health. Radio waves inhabit the low-energy end of the spectrum.

It’s important to remember that even visible light is a form of electromagnetic radiation (which falls in the 400 to 700 nanometre range – lower than gamma and X-rays but higher than microwave and radio).  Magnetic fields are generally thought to be safe, and many people use magnetic induction cooktops in their homes. WiTricity says the fields generated by its equipment doesn’t emit RF waves that interfere with other devices (RFI), as can happen with the many household devices (doorbells, cordless phones, microwave ovens, pest control devices, touch control lamps and of course Wi-Fi devices) that operate in the 2.4 GHz and 900 MHz frequency ranges.

WiTricity might not immediately be able to power your central air conditioning unit or laundry equipment, but it – and similar technologies – can move us one step closer to the world without wires that is the future.