The wireless charging system created by University of Washington engineers. The charging laser and guard lasers are normally invisible to the human eye, but red beams have been inserted in place of the guard beams for demonstration purposes.
Mark Stone/University of Washington
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.”
The University of Washington engineers behind the wireless charging system for mobile devices.
Standing (left-to-right): Vikram Iyer, Shyam Gollakota, Elyas Bayati.
Seated (left-to-right): Rajalakshmi Nandakumar, Arka Majumdar.Mark Stone/University of Washington
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.
Illuminated in red is one of the 3-D printed retroreflectors, which reflects the low-power guard beams to diodes on the laser emitter. Interruption of the guard beams triggers a safety system which blocks the charging beam.Mark Stone/University of Washington
“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 UW team’s prototype laser emitter. The high-powered guard beam is emitted from the central port. Four low-powered guard beams are emitted from ports surrounding the guard beam. Next to each guard beam port are clear photodiodes, which detect the guard beams when they’re reflected back to the emitter by retroreflectors on the phone.Mark Stone/University of Washington
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.”
The UW team’s prototype heatsink assembly, which can be attached to the back of a smartphone, consists of a photovoltaic cell (silver square, top) attached to a thermoelectric generator (in white). The generator is mounted on top of an aluminum heatsink. The entire assembly is only 8mm thick and 40mm wide.Mark Stone/University of Washington
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.
Learn more: Using a laser to wirelessly charge a smartphone safely across a room
The Latest on: Battery charging via laser
via Google News
The Latest on: Battery charging via laser
- Father’s Day Gift Guide: The Best Golf Accessories For Dadon May 20, 2022 at 4:00 am
If Dad loves golf, that passion makes your Father’s Day shopping easy. The key is to skip clubs. They are too personal, have too many variable specs, need to be fitted, and a new putter, driver or ...
- Best Golf Laser Rangefinders YEARon May 17, 2022 at 5:31 am
They also usually run on batteries and so can be left in your bag between games for a much more hassle-free user experience than GPS units, which need regular charging ... a CR2 battery and a clip ...
- The Best Items In The Binding Of Isaacon May 12, 2022 at 3:30 pm
From the Sacred Heart to the Magic Mushroom and the mighty Brimstone, here are some of the best and strongest items available in The Binding Of Isaac.
- Common Adhesive Tape Used to Build a Better Batteryon May 9, 2022 at 5:00 pm
the lithium metal tends to degrade fast during the battery’s charge and discharge cycles with the bare current collector. However, using the laser-induced silicon oxide (LI-SiO), this degradation didn ...
- ammo boxon May 5, 2022 at 5:00 pm
he laser-cut the top panel from 1/8″ plywood and secured a 20A solar charge controller, a four-in-one socket panel, and two banana plugs on its top face. [bennelson] is using 12 AWG wire to ...
- Shot Scope Pro L1 review: premium features in an affordable packageon May 4, 2022 at 3:07 am
The Shot Scope Pro L1 laser range ... You just charge them up before you go out to play and you’re all set. The last thing you want is to get to the course and discover the battery has died ...
- We tested the best vacuum cleaners including cordless, robots and pet friendlyon May 3, 2022 at 1:01 pm
It also has 25kpa suction, weighs less than the Dyson at 1.8kg and its 2,500mah battery is potentially capable ... They must be quick to charge, slow to run out, and they should also pack in ...
- 9 Best Cordless Hedge Trimmers: Compare & Saveon May 3, 2022 at 7:08 am
The hedge trimmer reaches up to 12 feet with 22-inch steel, a laser-cut blade that ... on the low setting on just a single charge using an 18V LXT 4.0Ah battery. This hedge trimmer is 25% ...
- 10 Best Wireless Mouse in India (May 2022) – Buyer’s Guideon April 28, 2022 at 5:00 pm
It is a 3 button USB laser mouse with ... on battery power, the battery lasts for 3 to 9 months if you are using a decent mouse. 3. Does the wireless mouse need charging? Most wireless mice ...
- on Fuel Cells, Kia Design Wins, Big German Vehicles, EV Charger Challenge, & the Mazda3on April 28, 2022 at 10:13 am
Even researchers who are involved in laser technology. So to that end ... What appears to be a white suitcase on the left side of that structure is actually an EV charger that is ordered via an app, ...
via Bing News