TOKYO – Imagine a world where the sensors monitoring a factory floor, the smart thermostat in your office, or the medical devices in a hospital never need their batteries changed. This could soon be a reality, thanks to a breakthrough in wireless energy transmission that uses light, not batteries or cords, to deliver power.
A research team from the prestigious Institute of Science Tokyo has unveiled a groundbreaking system that can wirelessly transmit power to small electronic devices using a focused beam of LED light. Their method successfully delivers energy over impressive distances of up to 16 feet (5 meters), presenting a potential paradigm shift for how we power the ever-expanding universe of Internet of Things (IoT) devices.
The study, which marks a significant step toward practical optical power transmission, was published on November 3rd in the high-impact journal Optics Express. You can read the full, detailed findings in the official publication here: Study published in Optics Express.
Solving the IoT's Power Problem with a Beam of Light
The core concept is elegantly simple. The system directs a narrow beam of light from a high-power infrared LED onto a small photovoltaic cell—essentially a tiny solar panel—attached to a device. This cell then converts the light energy into electrical power. This approach directly addresses one of the biggest hurdles in the IoT sector: the unsustainable cost and logistical nightmare of maintaining and replacing batteries in billions of widely dispersed sensors.
"While the idea of transmitting power with light isn't new, previous systems have largely relied on laser beams, which can pose safety risks to eyes and skin," explained Tomoyuki Miyamoto, who led the research alongside Mingzhi Zhao. "Our key innovation was in choosing high-powered infrared LEDs as a much safer alternative, and then engineering a way to focus their beam with incredible precision."
https://pixabay.com/de/photos/laser-laserlicht-forschung-labor-11646/
A tightly focused light beam, similar to the one used in the new wireless power system, illuminates a path in a laboratory setting.
The Secret Sauce: A Dynamic, "Smart" Lens System
The team's success in achieving a 16-foot range lies in its sophisticated optical setup. At the heart of the transmitter is a two-stage lens system. A fixed lens does the bulk of the beam-shaping, but the real magic comes from a dynamic liquid lens that can adjust its focus on the fly. This ensures the LED beam remains sharp and concentrated enough to hit a small photovoltaic target from across the room, minimizing energy loss over distance.
But what if the device is moving? The system has an answer for that, too.
Power on the Move: Tracking Targets Day and Night
In a real-world environment, IoT sensors aren't always stationary. To address this, the researchers integrated a full motion-tracking system. Using a depth-sensing camera (an Intel RealSense D435), the system can locate the small solar cells on the target device.
During the day, it uses standard imaging, but at night or in low light, it relies on retroreflectors on the target—similar to how a bicycle reflector works. An AI model then processes this data and controls a two-axis mirror and the liquid lens to continuously steer and focus the beam onto the moving target, ensuring a constant power supply regardless of the device's location or the ambient lighting.
"This reliability under all conditions is non-negotiable for industrial applications," said Mingzhi Zhao. "A sensor monitoring a robotic arm or a remote pipeline can't afford to lose power because it moved into a shadow or because the sun went down."
The Road Ahead: From Lab to Life
While the proof-of-concept is robust, the researchers are upfront about its current limitation: efficiency. In tests, the system converted 56.2% of the source energy into delivered power, with losses primarily from radiation spread and absorption by the liquid lens.
However, the team is optimistic. "We are already working on optimizing the LED and optics, and we believe we can push the efficiency to 80% or higher," Miyamoto stated. "At that level, real-world applications become far more feasible."
The long-term potential is vast. This technology could one day power sensor networks in smart factories and farms, eliminate wiring for smart home security cameras, and even keep implantable medical sensors running indefinitely without invasive surgery for battery replacement. We may be on the cusp of finally cutting the cord—for power itself.
