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As the Internet of Things (IoT) expands, powering numerous connected devices indoors has become increasingly challenging. Conventional solutions such as batteries or wired connections have clear limitations: batteries require frequent replacement or charging, and cables limit mobility and flexibility. These constraints have spurred interest in optical wireless power transmission (OWPT), which delivers energy through light, converting it back to electricity at the device using photovoltaic (PV) receivers.
Researchers at Science Tokyo have developed a new LED-based OWPT system that addresses the shortcomings of both batteries and conventional wireless power methods. Unlike laser-based systems, which pose safety risks and require strict regulatory compliance, LEDs provide inherently safe energy transmission, while remaining cost-effective and durable. The challenge, however, has been maintaining consistent power over distance and under changing lighting conditions.
The team’s solution integrates a dual-mode, adaptive design capable of operating seamlessly in both bright and dark indoor environments. A novel double-layer lens system, combining a tunable liquid lens with an imaging lens, automatically adjusts the light beam’s spot size to match the PV receiver’s distance and dimensions, optimizing energy transfer. A motorized reflector, controllable in both horizontal and vertical axes, aligns the beam precisely, guided by a depth camera with RGB and infrared sensors. This setup allows the system to detect the position of PV receivers and track the beam’s irradiation spot, ensuring accurate delivery.
Artificial intelligence enhances the system’s efficiency. A convolutional neural network based on the Single Shot MultiBox Detector algorithm processes input from the sensors, enabling the system to sequentially power multiple devices of varying sizes without interruption. Retroreflective sheets surrounding the PV receivers provide clear outlines in both light and dark conditions, further improving targeting accuracy.
According to TechXplore, the resulting system can transmit power stably up to five meters, automatically switching between devices and adapting to environmental changes. Beyond commercial IoT applications such as smart factories and connected homes, this technology could support defense and security operations by enabling safe, wireless power delivery to sensors, communications nodes, and autonomous devices in indoor facilities where wired infrastructure is impractical or vulnerable.
By combining adaptive optics, AI-based detection, and LED-based power transmission, this auto-OWPT platform represents a practical step toward scalable, safe, and flexible indoor energy solutions for the growing IoT ecosystem.
The research was published here.
