sOLVE mE A thermopile is made out of N=240 series Ti/Ni thermocouples on top of
ID: 1770684 • Letter: S
Question
sOLVE mE
A thermopile is made out of N=240 series Ti/Ni thermocouples on top of a membrane fabricated by bulk micromachining of silicon. The thermocouples sit on top of a silicon dioxide layer as electrical insulator and are placed in such a way that one side of the thermocouple junctions is located at the IR radiation exposed area on top of the thin membrane, while the other, or reference junctions, are located on top of the thick frame of full thickness of the silicon wafer. The hot area is covered by a IR radiation absorber film The output voltage at a given radiation of 1 W is 59 mV. Estimate the value of T in the membrane.
Explanation / Answer
For a thermopile we know that in the series connection the voltage generated is N times higher.
Hence the effective voltage will be = 59mV/240 = 0.245 mV
THermocouple constant of Ti/Ni thermocouples should be taken from the text you are following.
Hence we can relate temperature and voltage as .
T * Constan * 1 = 0.245
Constant must be in units of mV/W.K
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