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Smart Energy Harvesting: A new method for Electronics, Part 1

Electronic power management is one of the most important aspects of the design of an integrated electronic circuit. A correct design of the of the blocks of the IC in the stand-by modes of operation avoids waste in electric energy when the IC is not at full power: this practice ensures good autonomy of the smartphone or tablet that has that IC inside and the user has the freedom to use it without the need for frequent recharging of the batteries. When the IC is in operation, low energy consumption is a guarantee for low heating of the electronic circuitry; that’s because a part of the electric energy flowing into the integrated circuit becomes heat, increasing the temperature of the electronic device, which is undesirable for the user who would rather prefer to spend less time recharging the batteries. Users also want a longer time elapsed from one charge to the next.

To help to further enhance the power management process, recently new batteries with a very short time of recharge (in the order of magnitude of a few seconds) have been introduced by a group of researchers from the Université Paul Sabatier in France, the Drexel College of Engineering in the US and the Bar-Ilan University in Israel (see Figure 1):

Researchers have long sought electrically conductive materials for economical energy-storage devices. Two-dimensional (2D) ceramics called MXenes are contenders. Unlike most 2D ceramics, MXenes have inherently good conductivity because they are molecular sheets made from the carbides and nitrides of transition metals like titanium. ” (Source: ScienceDaily)

Figure 1

The new structure build in a new material, the MXene, allows the flow of ions with low resistance path to engine ultrathin electronics devices. (Source: pubs.acs.org)

The new structure build in a new material, the MXene, allows the flow of ions with low resistance path to engine ultrathin electronics devices. (Source: pubs.acs.org)

Fast charging of the batteries means increased freedom for the user of these electronics devices. The next step is to minimize the dependency from external power sources and this is just what the researchers of University of Washington in Seattle have done by means of a cell phone able to make calls without a battery (see Figure 2):

Realizing that vision required rethinking almost everything about how cell phones function today. In order to operate without a battery, the phone would have to rely only on energy that it could harvest from its surroundings. Ambient light can be turned into a trickle of electricity with solar panels or photodiodes. Radio-frequency TV and Wi-Fi broadcasts can be converted into energy using an antenna. …The first thing the team tackled was communication. Smith's lab developed a technique called backscatter that allows a device to communicate by reflecting incoming radio waves…A nearby basestation has circuitry for converting and connecting to the digital cellular network, currently via Skype. The prototype basestation uses an unlicensed frequency, limited to low-power transmissions. Because the phone relies on those signals for its energy harvesting, it has a range of just 15 meters from the basestation. ” (Source: WIRED).

Figure 2

The phone with no battery. (Source: wired.com)

The phone with no battery. (Source: wired.com)

Let’s see the basic schematic diagram (see Figure 3a) of an electronic circuit that realizes the harvesting of radio waves and converts the pulsed energy into electrical energy. That energy can be utilized to power an IC, which does not consume energy from its battery, to work properly. The signal received by the antenna is first rectified, then the voltage is set as the input to a voltage detector IC which activates a switch which forward biases the LED and hence, turned on (see the red light in Figure 3b).

Figure 3

The voltage detector is powered by the energy antenna thus the battery is not consumed to feed this IC. (Source: YouTube)

The voltage detector is powered by the energy antenna thus the battery is not consumed to feed this IC. (Source: YouTube)

Electronics technology has the huge potential of working with low dependency from external sources of energy. Do you find this option interesting? Do you think this field of research will be further developed?

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