by josh perry, editor
researchers at the university of washington (seattle, wash.) have created a system for charging smartphones using a laser array with one man charging beam and four safeguard beams and a receiver on the back of the phone that could charge the device from across the room.
three university of washington grad students have published research on using lasers to wirelessly charge phones. (james maltman/university of washignton)
according to a report from the university, if the safeguard beams are broken then they will shut down the more powerful charging beam. also, the receiver on the phone converts the laser into electrical energy that is directed into the battery. as long as there is line of sight with the laser, the device will charge without being plugged in.
“this is not a replacement to a phone battery,” the report explained, “which is still needed to power the phone, but this will be a separate outlet that people can use in addition to their normal charging ports.”
the three-year project was derived from previous work on wireless charging and to expand wireless charging from near-field to longer distances.
“when building their prototype, safety was their number one priority,” the report said. “they factored in additions like heat sinks to siphon off excess heat generated by the energy transfer. the prototype succeeded in being able to charge a cellphone at the approximate rate that a normal two-watt usb charger would be able to.”
the rate of charging is variable depending on the size of the laser and the receiver, although the researchers are now turning their attention to making the system smaller for commercialization.
the report concluded, “the system allows for a larger freedom of movement when charging, as the phone is not tethered to a cord or base, and on a larger scale, the machines will not have to return to their home base to be recharged after only using half their battery life. the system is still being developed for consumer and large-scale use but has the potential to change the way we charge.”
the research was recently published in proceedings of the acm on interactive, mobile, wearable, and ubiquitous technologies. the abstract stated:
“we demonstrate a novel laser-based wireless power delivery system that can charge mobile devices such as smartphones across a room.
“the key challenges in achieving this are multi-fold: delivering greater than a watt of power across the room, minimizing the exposure of the resulting high-power lasers to human tissue, and finally ensuring that the design meets the form-factor requirements of a smartphone and requires minimal instrumentation to the environment.
“this paper presents a novel, and to the best of our knowledge, the first design, implementation and evaluation of an end-to-end power delivery system that satisfies all the above requirements. our results show that we can deliver more than 2 w at ranges of 4.3 m and 12.2 m for a smartphone (25 cm2) and table-top form factor (100 cm2) receiver respectively.
“further, extensive characterization of our safety system shows that we can turn off our laser source much before a human moving at a maximum speed of 44 m/s can even enter the high-power laser beam area.”