Advanced LED package with temperature sensors and microfluidic cooling

Light-emitting diodes (LEDs) are revolutionizing the illumination with energy savings and enhanced functionality. However, around 80% of the input power will be still transferred to heat. As the elevated temperature negatively affects the maximum light output, efficiency, quality, reliability and the lifetime of the SSL systems, thermal management is a key design aspect for LED products in terms of cost and performance. LEDs also offer controllability of their spectral, spatial distribution, color temperature, and etc. But the light quality and quantity depend on the temperature stability. In this work, an innovative LED package was manufactured with conventional silicon processing and microelectromechanical systems (MEMS) technology with temperature sensors and microfluidic cooling. A group of sensors could provide the accuracy temperature measurement of LED chip and further controlling. And two-phase cooling in the micro fluid channels is introduced to cool high power LEDs and maintain the temperature to be relatively stable. Furthermore, the LEDs' waste heat that evaporates the water can simultaneously act as a driving force in a thermally driven pump. Results show both the diode and resistor temperature sensors have accuracy within 1 degree Celsius and the thermally driven pumps can be used for the LED which is powered as high as 1.65 watts around 100°C.