Bluetooth and Wi-Fi have allowed people to enjoy many years of convenience, but wireless charging technology has been dragging on the charging power and transmission distance. The good news is that a research team from the University of Washington has just demonstrated their 'Laser Interior Wireless Charging Solution'. The researchers placed an 'energy battery' on the back of the smartphone and then used a near-infrared spectrum laser to hit the center receiver.
This laser system can wirelessly charge indoor mobile phones
Actual measurements show that the system's charging power is comparable to that of a traditional USB cable. Even at a distance of 4.3 meters (14 feet), the laser can deliver 2W of power to a 97 square centimeter (15 square inches) receiver.
A prototype consisting of a photovoltaic cell, a thermal motor (white part) and an aluminum block (located at the bottom).
Research co-author Vikram Iyer said: The mobile phone can be set to send high-frequency signal sounds that the human ear can't hear, so that the energy transmitter can automatically sense its position.
In terms of safety, the research team also presets multiple barriers: The image above is a laser emitter surrounded by four protective beams and photodiodes. The sensor will cut off the circuit when it senses that someone is approaching.
The red part is a mirror (a protective beam is launched back) to prevent someone from being burned while crossing the laser beam.
To reduce excess heat from energy transfer, researchers used aluminum bars to dissipate heat. Of course, not all of the heat is wasted because the small thermal motor above captures energy and feeds it to the cell phone battery.
Laser wireless charging project team, from left to Vikram Iyer, Rajalakshmi Nandakumar, Shyam Gollakota, Arka Majumdar, Elyas Bayati.
The research team stated that the future iterative system is expected to increase the transmission area to 100 square centimeters (15.5 square inches) and reach a distance of 12 meters (39 feet), which can charge devices placed anywhere on the table.
Details of this study have been published in a recently published Association journal titled "Charging a Smartphone Across a Room Using Lasers".
