將LED設計成可穿戴電子產品

　　GaN更高的效率被用于可穿戴和能量收集設計的低功率指示燈。本文著眼于最新的LED技術如何在超低功耗系統中提供重要反饋。

　　氮化鎵（GaN）是一種非常有趣的能量收集系統材料。3.5電子伏特的帶隙本身以及建筑發光LED器件和高電子遷移率和更高的效率比硅讓這些LED運行在較低的電流，開放的超低功耗的應用程序，可以通過提供能源的環境動力。GaN不僅是發光二極管的一種令人興奮的材料，而且還有研究如何將這種材料也用作壓電裝置，以從運動中產生動力本身。這兩種趨勢正在引導GaN進入可穿戴和醫療電子領域的令人興奮的新領域。

　　傳統上很難在體積上取得成本效益，因為GaN結構的襯底是碳化硅（碳化硅）或藍寶石來處理器件所能產生的熱量。最近的發展已經取代了低成本的硅襯底，允許使用標準CMOS設備和硅晶片，從而大幅降低氮化鎵基LED的成本。這就打開了在柔性襯底和可穿戴設計中使用這種低功率LED的可能性。

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　　The key issue for energy-harvesting applications is of course the power consumption. However， as these are high-brightness LEDs， the devices can be reduced in both size and power and still provide light for a range of wearable designs such as system monitors， and even as decoration in the material.

　　Pure GaN LEDs are at the UV and blue end of the spectrum and were originally used as the laser in Blu-ray systems， but can be doped with Indium and aluminum to generate green and white light. This makes use of the higher electron mobility and band gap of GaN and provides a range of colors for the LEDs. These can be powered by energy harvested from movement via vibration or solar cells. The vibration energy from movements can be captured by piezo electric devices， such as the Mide V22B， which feed into a power management sub-system that either provides the power directly to the LEDs or， more commonly， charges a battery as a store for the energy.