How about a cellphone that never needs to be plugged in?

The Concept

Cellphones with solar charging capabilities are fast becoming a hot seller in the market though a vast majority of mobile phones in the market still come with the old plug-and-charge mechanism since they are loaded with features that consume a lot of energy. However, developers are hard at work trying to come up with phones that don’t need to be charged via a plug and don’t even need constant sunlight to keep their batteries juiced up. Using this thought as a starting point, a team of developers from the University of Cambridge has created a prototype cellphone that can charge itself via ambient light. Led by IEEE fellow Arokia Nathan, the team used thin-film hydrogenated amorphous silicon in an array of solar cells that were embedded within the phone's OLED display. Since the front of the screen projects around 36 percent of the light generated by the phone, a vast majority of it is leaked out through the edges. IGNIS Innovation, a Canadian firm, proposed that this wasted light could be harnessed to re-power the phone and they achieved this by setting up the display’s edges with thin-film PV cells to capture this light.

Solar Cells in Smartphone Screens

The Inspiration

Use of sustainable energy resources is a trend that major electronics brands are investing into more seriously and solar cell technology is being investigated and optimized for usage in household electronics on a vast scale now. One obstacle that has prevented PV cells from being used in home electronics so far is the fact that the current state of technology prevents them from generating sufficient charge to power most gizmos found in our homes. This has led manufacturers into exploring ways to make their gadgets efficient enough to be run on solar power alone.

In past 5 years, a number of solar powered gadgets have been introduced that can function solely on solar energy/ambient light. Since cellphones and laptops have become an essential part of our lives, having devices that need charging less often could prove to be monumental in the global struggle to save the environment. Of course, having such devices would also offer users the freedom to use their gizmos even in places where a charging point is not available such as aboard subways, metros, other modes of public transportation and even while hanging outdoors.

Where are we now?

At the moment, the electronics industry is essentially split down the middle with one half focusing on developing devices that charge themselves on solar/ambient light via in-built PV panels and the other half working hard to come up with more powerful solar/ambient light chargers for the line of products that don’t have solar cells embedded into them.

However, a vast majority of existing electronic devices still need charging via traditional outlets since they are loaded with features that consume a lot of electricity and would need bigger PV panel chargers to run. The ideal solution for this particular dilemma, of course would be to not only develop more powerful solar chargers but also the devices that are efficient enough to run on minimal electricity like this prototype cellphone created by researchers at the IGNIS Innovation and University of Cambridge.

What makes it stand out?

This prototype phone seeks to make optimal use of the light created by the cellphone’s display and use 64 percent of OLED light that is spilled from the edges. In the phone, the edge of the screen features an array of cells. The team, based at University College London until recently, discovered that though solar panels were a great way to charge cellphones sustainably, they exposed the phone’s battery to voltage fluctuations that could damage it irreversibly.

To counter this problem and extract electricity more efficiently via solar panels, the team developed a thin-film transistor circuit that could negate the effects of voltage spikes. This ensures that a complex circuitry charges the battery, which under the right lighting conditions can generate as much as 165 microwatts per square centimeter. This energy harvesting system converts five percent of ambient light to electricity, provides a peak efficiency of 18 percent PV array and gives an average efficiency of 11 percent. In layman’s terms, this means that the battery gets a maximum power output of five milliwatts generated by a 3.7-inch smartphone screen.

Where do we go from here?

The small scale wireless energy harvesting as demonstrated by this cellular handset prototype are beneficial in many ways. However, an alternate source of plug-free charging could be provided by using an induction coil in a magnetic resonance coupling. To generate an oscillating magnetic field, a coil of conductive material is used and alternating current is run through it. A phone or an MP3 player, with a current in a coil embedded in it could use this magnetic field to generate its own power via flat thin-film coil. Though the coil cannot be made powerful enough to run a PC but mobile devices with scaled-down magnetic coupling could be a real possibility in the future. Further improvements in developing sustainable resources like MEMS-based kinetic energy harvesting can also prove useful in energy scavenging schemes and provide a huge boost to the process of preservation of earth’s resources and environment.

Related Trends

1. Aeolus phone

Aeolus Phone

Built from renewable materials, the Aeolus mobile phone was designed to harvest renewable energy sources like solar energy and wind power. The concept was created by industrial designer Cyrene Quiamco and features a simple, energy-efficient single color LCD screen. Onboard solar panels recharges the phone’s battery when the wind isn’t blowing and on more windy days a power generating fan can be used to charge the device.

2. Nokia Eco Sensor

Nokia Eco Sensor

While most cellphone manufacturers are hard at work trying to come up with the next big efficient-energy solar powered handset, Finnish multinational mobile phone maker Nokia has come up with a “green” mobile phone that not only monitors the environment but also the weather and the user’s health. Powered by alternative energy sources, the phone comes with a wearable sensor unit that enhances our awareness both, about the environment and about us. To make it the ideal “green” mobile phone, the Nokia Eco Sensor Concept is designed for optimal energy consumption and manufactured with bio-materials and reclaimed materials in keeping with the company’s waste reduction principles. The display of this phone uses electro-wetting technology i.e. expanding oil droplets that make the pixels on the screen light up ensuring that the screen consumes less energy than OLED or LED display units.

3. Samsung Blue Earth

Samsung Blue Earth

Small enough to fit in your pocket yet sleek enough to be shown off to friends, the Samsung Blue Earth comes with full solar panel on its back. The gorgeous green touch phone can generate enough power to charge itself and marks the first legitimate attempt by an internationally sold cellphone brand to launch a genuine solar powered phone.

4. ZTE Coral-200

ZTE Coral-200

The Coral-200 by Chinese mobile manufacturer ZTE is a relatively basic solar phone that offers around 15 minutes of talk time for every hour of sunlight it is exposed to. Priced at just 40 dollars, the solar powered handset is based on Dutch-based innovation and is aimed at people who do not have regular access to the grid. Since there are over two billion of such people around the world, this phone could be a real hit if it is marketed the right way.