The power supply is by induction magnetic field

Mobile phones or portable chargers are perhaps condemned. At the Consumer Electronic Show (CES), the track of the high-tech which was held in Las Vegas from 7 to 10 January, many manufacturers made recharge contactless solutions: simply place the apparatus on a plate to it recharges. This is the case of the Powerpack, developed by the Israeli company PowerMat, to be launched in France in June. It consists of two components: a special battery in his phone (30 euros) and a support on which it is his laptop to load (80 euros). The power supply is by induction (magnetic field). Duracell markets already in the United States a similar system, called "myGrid" (from $ 65).

These solutions can be practical, but have a size disadvantage: it is always necessary to link support to an electrical outlet. A barrier that will perhaps more exist in a few months. Two American companies, RCA and Witricity (contraction of "wi - Fi" and "electricity"), announced to the those that they were going to market solutions for remote loading or a power supply. This time, the transmitter is built into a wall and transmits energy to the phone via a small antenna. Developed in 2008 by a team of scientists from MIT (Massachusetts Institute of Technology), WiTricity technology relies on the principle of magnetic coupling resonance: two objects having the same wavelength (or frequency of resonance) can exchange energy via electromagnetic waves.

Not yet standard

This solution has two advantages over the Powerpack type media. First, the mobile device can be located a few metres from the transmitter. Second, this solution would supply any type of appliance: refrigerator, computer... In the these, the Chinese brand Haier has presented a prototype of TV with this technology, which is expected to be commercialized by the end of the year by Witricity. At the last Ceatec, the grand Salon of the electronics in the Japan, in October 2009, Sony had already presented a 22 inches LCD TV that worked without be connected to an electrical outlet.

The RCA is a little different: a key-sized USB, Airnergy module would be able to capture these Wi - Fi waves around him and to convert them into electricity. As a first step, should connect this module to the mobile device USB jack. But ultimately RCA provides design batteries incorporating this system directly.

Despite the interest of these different solutions, they cannot develop without a standard. It is the objective of the Wireless Power Consortium (WPC), an association, consisting of 21 specialists in electronics (Philips, National Semiconductor, Sanyo...) but also Nokia and RIM (BlackBerry). It wants to develop a joint solution called "Qi" (deciding "chi", in reference to the fundamental energy). To accelerate the adoption of this standard, Texas Instruments, Member of the WPC, presented to the these bqTesla kit (transmitter, receiver, coil, magnet, documentation). It should be available at the end of the first quarter of 2010 at a cost of $ 250.

Too low performance

Remain two obstacles. First, these solutions may encounter regulations regarding radiation from magnetic fields. Second, the broadcast wireless results in losses. "Comparison, an RFID antenna emits 1-2 watts, but the label located at 1 metre will retrieve only a few tens of microwatts", says Fabrice Roudet, responsible for projects and an expert in wireless in Schneider Electric. According to researchers from MIT, Witricity performance 2 metres is 40. Step really fast and practical. According to RCA, it would take about 4 and a half hours to fully recharge a "smartphone" near a Wi - Fi kiosk!