Why Is Heat Management Critical in Wearable LED Devices?
LEDs convert approximately 30–50% of input electrical energy into light. The remaining 50–70% becomes heat. In a full-body panel, this heat dissipates across a large surface area with natural convection. In a wearable device sitting on the nose bridge, the thermal challenge is entirely different.
The Orbital Defender drives its LED array at >30mW/cm² continuous output for 10 minutes. Without thermal management, surface temperatures would exceed 45°C within three minutes. That is uncomfortable at best, potentially harmful at worst. Our engineering goal was to maintain surface temperature below 39°C (just above body temperature) throughout the full session.
How Does Copper-Core Design Solve LED Heat Problems?
Thermal conductivity is the key material property. Aluminum, common in consumer electronics, conducts heat at 205 W/m·K. Copper conducts at 385 W/m·K, nearly twice as efficiently. We use a custom copper-core PCB substrate that pulls heat away from the LED junction and spreads it across the entire internal chassis.
The copper substrate connects to an integrated heat spreader in the temple arms. When the device is worn, the temple arms contact the head behind the ears, a region with excellent blood perfusion. Body-contact cooling transfers heat from the device into the body’s natural thermoregulatory system, effectively using the wearer as a heat sink.
Is Passive or Active Cooling Better for Wearable Devices?
Active cooling (fans, thermoelectric coolers) adds weight, noise, complexity, and failure points. For a 34-gram wearable device, active cooling is impractical. Our passive approach achieves the thermal targets without any moving parts.
The passive system combines three thermal pathways: (1) copper-core substrate for junction-to-case spreading, (2) thermal gap pad connecting the PCB to the bio-acetate frame, and (3) temple arm heat spreaders for body-contact dissipation. Together, these maintain a ΔT of less than 6°C between the LED junction and the skin-facing surface.
Frequently Asked Questions
The surface remains below 39°C throughout a full 10-minute session: warm but never uncomfortable. This is achieved through a copper-core PCB substrate and passive heat spreading through the temple arms.
Active cooling (fans, thermoelectric coolers) adds weight, noise, and failure points to a 34-gram wearable. Our passive copper-core solution achieves the same thermal targets without moving parts, maximizing reliability and comfort.
Yes. The device maintains surface temperature below 39°C, just above body temperature. The copper-core substrate and body-contact cooling through the temple arms ensure heat is dissipated safely away from the periorbital tissue.
