Thermal Engineering in Fanless AI Wearables: Pyrolytic Graphite Sheets vs. 0.3mm Titanium Micro-Vapor Chambers

Executive Conclusion: In-Plane Thermal Conductivity (1,500 W/m·K) Is the Key to Eliminating Temple Hotspots

In RECIWO Labs' infrared thermography tests, an unspread 1.8W SoC inside a plastic eyeglass temple creates a localized 48.5°C skin hotspot within 95 seconds—forcing immediate thermal throttling. Laminating a 0.08mm synthetic pyrolytic graphite sheet (1,600 W/m·K in-plane conductivity) coupled to a flexible copper-mesh hinge bridge distributes heat across both the front lens rim and temple arm, dropping peak skin contact temperature by 8.2°C and doubling continuous multimodal AI runtime.

1. Comparing Ultra-Thin Heat Spreaders for Sub-6mm Wearable Enclosures

Inside a 5.5mm eyeglass temple, Z-axis thickness is limited to less than 0.35mm for thermal management materials:

2. Using Walking Airflow: Why Front-Rim Heat Dissipation Doubles Outdoors

When a user walks at a normal pace of 1.3 meters per second, forced convective heat transfer across the front eyeglass bridge is 2.4x higher than behind the ear where hair traps warm air. Routing heat forward from the temple SoC into the nose-bridge magnesium core turns normal walking motion into a silent passive radiator.

[4nm AI SoC (Left Temple)] ──> [0.3mm Micro-Vapor Chamber]
                                        │
                                        ▼ (Flexible Graphite Bridge Through Hinge)
                               [Front Frame Rim Convective Cooling During Walking]