Although mobile devices such as tablets and smartphones let us communicate, work and access information wirelessly, their batteries must still be charged by plugging them in to an outlet. But engineers at the University of Washington have for the first time developed a method to safely charge a smartphone wirelessly using a laser.
As the team reports in a paper published online in December in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable & Ubiquitous Technologies, a narrow, invisible beam from a laser emitter can deliver charge to a smartphone sitting across a room — and can potentially charge a smartphone as quickly as a standard USB cable. To accomplish this, the team mounted a thin power cell to the back of a smartphone, which charges the smartphone using power from the laser. In addition, the team custom-designed safety features — including a metal, flat-plate heatsink on the smartphone to dissipate excess heat from the laser, as well as a reflector-based mechanism to shut off the laser if a person tries to move in the charging beam’s path.
“Safety was our focus in designing this system,” said co-author Shyam Gollakota, an associate professor in the UW’s Paul G. Allen School of Computer Science & Engineering. “We have designed, constructed and tested this laser-based charging system with a rapid-response safety mechanism, which ensures that the laser emitter will terminate the charging beam before a person comes into the path of the laser.”
Gollakota and co-author Arka Majumdar, a UW assistant professor of physics and electrical engineering, led the team that designed this wireless charging system and its safety features.
“In addition to the safety mechanism that quickly terminates the charging beam, our platform includes a heatsink to dissipate excess heat generated by the charging beam,” said Majumdar, who is also a researcher in the UW Molecular Engineering & Sciences Institute. “These features give our wireless charging system the robust safety standards needed to apply it to a variety of commercial and home settings.”
The charging beam is generated by a laser emitter that the team configured to produce a focused beam in the near-infrared spectrum. The safety system that shuts off the charging beam centers on low-power, harmless laser “guard beams,” which are emitted by another laser source co-located with the charging laser-beam and physically “surround” the charging beam. Custom 3-D printed “retroreflectors” placed around the power cell on the smartphone reflect the guard beams back to photodiodes on the laser emitter. The guard beams deliver no charge to the phone themselves, but their reflection from the smartphone back to the emitter allows them to serve as a “sensor” for when a person will move in the path of the guard beam. The researchers designed the laser emitter to terminate the charging beam when any object — such as part of a person’s body — comes into contact with one of the guard beams. The blocking of the guard beams can be sensed quickly enough to detect the fastest motions of the human body, based on decades of physiological studies.
“The guard beams are able to act faster than our quickest motions because those beams are reflected back to the emitter at the speed of light,” said Gollakota. “As a result, when the guard beam is interrupted by the movement of a person, the emitter detects this within a fraction of a second and deploys a shutter to block the charging beam before the person can come in contact with it.”
The next generation of nano-scale optical devices are expected to operate with Gigahertz frequency, which could reduce the shutter’s response time to nanoseconds, added Majumdar.
The beam charges the smartphone via a power cell mounted on the back of the phone. A narrow beam can deliver a steady 2W of power to 15 square-inch area from a distance of up to 4.3 meters, or about 14 feet. But the emitter can be modified to expand the charging beam’s radius to an area of up to 100 square centimeters from a distance of 12 meters, or nearly 40 feet. This extension means that the emitter could be aimed at a wider charging surface, such as a counter or tabletop, and charge a smartphone placed anywhere on that surface.
The researchers programmed the smartphone to signal its location by emitting high-frequency acoustic “chirps.” These are inaudible to our ears, but sensitive enough for small microphones on the laser emitter to pick up.
“This acoustic localization system ensures that the emitter can detect when a user has set the smartphone on the charging surface, which can be an ordinary location like a table across the room,” said co-lead author Vikram Iyer, a UW doctoral student in electrical engineering.
When the emitter detects the smartphone on the desired charging surface, it switches on the laser to begin charging the battery.
“The beam delivers charge as quickly as plugging in your smartphone to a USB port,” said co-lead author Elyas Bayati, a UW doctoral student in electrical engineering. “But instead of plugging your phone in, you simply place it on a table.”
To ensure that the charging beam does not overheat the smartphone, the team also placed thin aluminum strips on the back of the smartphone around the power cell. These strips act as a heatsink, dissipating excess heat from the charging beam and allowing the laser to charge the smartphone for hours. They even harvested a small amount of this heat to help charge the smartphone — by mounting a nearly-flat thermoelectric generator above the heatsink strips.
The researchers believe that their robust safety and heat-dissipation features could enable wireless, laser-based charging of other devices, such as cameras, tablets and even desktop computers. If so, the pre-bedtime task of plugging in your smartphone, tablet or laptop may someday be replaced with a simpler ritual: placing it on a table.
The Latest on: Battery charging via laser
The laser that could replace your phone charger
on March 4, 2018 at 11:00 pm
The first challenge they faced was how to charge a phone via laser without harming people ... of the phone to convert the energy provided by laser into electrical energy, charging the cellphone’s battery. If the phone is visible and in an unbroken ... […]
These Researchers Used A Laser To Wirelessly Charge A Smartphone
on February 26, 2018 at 11:01 am
Today’s smartphones have an average battery life of 10 to 14 hours ... a thin power cell on the back of the smartphone to charge the smartphone using power from the charging laser beam. The team added customized safety features to protect the user ... […]
Always running out of battery? This new laser system can charge your smartphone from across the room
on February 21, 2018 at 10:11 am
have developed a laser emitter that can safely charge a smartphone across a room as quickly as a standard USB cable. Researchers mounted a thin power cell to the back of a smartphone, which charges the smartphone using power from the laser. They custom ... […]
Melbourne PhD student Han Lin leads revolutionary battery charge
on January 22, 2017 at 4:00 pm
Now he's a leader in a global quest to make a commercial "supercapacitor" battery ... ratio by using laser printing technology to produce graphene in an interdigital structure, which leaves ions with much less distance to travel to charge and discharge. […]
Sony unveils smartphone with laser camera, ‘smart' battery
on September 1, 2016 at 4:15 am
For example, the phone can learn your sleeping habits, so that if you are charging the phone overnight, the battery will charge to 90 percent ... For example, users can do shopping via the projector. Sony's Xperia Agent is a competitor to Amazon's Echo ... […]
You Can Quickly Recharge This Backup Battery Using Your MacBook's Charger
on October 22, 2015 at 4:00 am
It’s the first backup battery that can be charged using your MacBook’s power adapter ... s compatible with both the original and newer versions. Swap your MacBook’s charging cable from your laptop to this battery and it will recover 50 percent ... […]
The iPhone 6 may have a different kind of wireless charging
on January 29, 2014 at 2:09 pm
At a time when the competition is offering wireless charging ... by simply using the power of the sun. Matt Margolis says the iPhone 6 and the 2014 iPod touch (if there will be one) may come with a display capable of increasing battery life. […]
Logitech G7 Laser Cordless Mouse
on December 21, 2005 at 4:00 pm
When optical tracking technology gave way to laser tracking, Logitech was immediately on ... and powers on without a hitch when the new battery is inserted. Each charge on the battery packs will power the G7 for around 7-8 hours of heavy gaming, or about ... […]
via Google News and Bing News