World’s First LED Wireless Power Transmission Achieved: Stable Energy Transfer Within 5 Meters

In a breakthrough that could reshape how indoor IoT devices are powered, researchers at the Institute of Science Tokyo have successfully converted LED light energy into electrical power—marking the first demonstration of battery-free and cable-free wireless power supply using high-power LEDs.

The technology belongs to the field of Optical Wireless Power Transmission (OWPT). Its core principle is straightforward: electrical energy is converted into light, transmitted through free space, and then converted back into electricity by a photovoltaic receiver. Unlike previous approaches that relied on lasers, this new method uses high-power LEDs, offering a safer and more cost-effective pathway for powering indoor devices.

Why LED Instead of Laser?

The key advantage of the LED-based approach lies in safety and cost. In indoor environments densely populated with IoT devices, wireless power systems must comply with strict safety regulations to avoid harm to human eyes and skin. Conventional laser-based solutions struggle to meet these requirements due to their high energy density. LED-based technology, by contrast, is inherently safer.

According to the research team, this characteristic makes it particularly suitable for building sustainable infrastructure for indoor IoT devices. Combined with AI image recognition, the system can simultaneously and continuously power multiple targets.

Overcoming Distance and Lighting Challenges

To address energy loss over longer distances and performance fluctuations under different lighting conditions, the research team developed a dual-mode adaptive system capable of automatically adjusting to both bright and dark indoor environments.

At the heart of the system is an adaptive optical module consisting of a tunable liquid lens and an imaging lens. This module automatically adjusts the beam spot size based on the receiver’s distance and dimensions, ensuring optimal energy transfer efficiency.

For precise beam targeting, the system integrates a depth camera and a stepper-motor-controlled adjustable mirror. The RGB sensor in the depth camera identifies the position of the photovoltaic receiver, while the infrared sensor locates the beam’s irradiation point.

Additionally, the researchers attached retroreflective film to the edges of the receiver. This film reflects the depth camera’s infrared light, clearly outlining the receiver’s contour even in complete darkness—ensuring stable operation around the clock.

AI-Enhanced Target Recognition

The team further introduced a convolutional neural network (CNN) based on the SSD algorithm, significantly improving target recognition accuracy. In experiments, the system demonstrated seamless operation in both illuminated and dark environments, successfully achieving efficient and stable energy transmission at distances up to 5 meters.

According to the research report, the LED chip used achieved a radiant flux of 1.53 watts.

Implications for Indoor IoT and Beyond

This breakthrough opens new possibilities for powering indoor IoT devices without batteries or cables. Potential applications include:

• Smart building sensors – temperature, humidity, occupancy, and air quality monitors

• Security cameras and access control – continuous power without wiring

• Retail and hospitality – electronic shelf labels, digital signage, and guest devices

• Healthcare and senior care – wearable and implantable medical sensors

As the technology matures, LED-based OWPT could become a foundational infrastructure for the next generation of connected indoor environments—safe, efficient, and scalable.