An inline sensing of coolant temperature inside a micro-channel for applications in ultra dense packed high power electronics

An indirect cooling mechanism with coolants flowing through micro-channels absorbing the heat emanating from the ultra dense high power electronics chips and field programable gate arrays (FPGA) has been reported as the successful thermal management process in recent times. In such schemes, it is imperative to control the flow rate of the fluid so as to maintain the normal operating conditions/temperature on the area to be cooled. Such requirement necessitates the measurement of the temperature inside the micro-channels so as to sustain the needed circulation speed of the coolant. In the present paper, experimental measurement of the temperature of the fluids flowing through a closed loop micro-channel, by inserting an inline all-fiber micro Mach - Zehnder interferometer (MMZI) inside the channel, has been reported. During the study, three different fluids viz. water, isopropyle alcohol and copper nano particle mixed iso propyle alcohol, were circulated, at different flow rates, inside the 0.6 mm2 channel. The variations in the characteristics of the light waves propagating through the fiber due to the presence of the fluid and its flow rate were observed on the optical spectrum analyzer. The temperature sensitivity of the MMZI for three fluids, in terms of shift in the output fringe pattern was determined as 0.372 nm/°C, 0.261 nm/°C. and 0.249 nm/°C, respectively.