Fabrication of freestanding thin Pt/W thermocouple by Joule heat welding

Abstract

A very-thin Pt/W thermoelectric element is fabricated on a small chip. The Pt and W thin wires having the diameter of 5 µm are attached on a Cu electrode chip, and these are electrically isolated by air grove on the chip. The tips of both thin wires are welded by the technique of Joule heating. The other ends of wires are connected to a voltmeter. Temperature of the constructed electro-thermal circuit is controlled by flowing of the current through the circuit. The observed voltage is found to be proportional to the temperature difference between the dissimilar welding point and the chip (room temperature) which satisfies the Seebeck effect. The Seebeck coefficient is found to be about 0.2 µV/K. The temperature distribution of 5 µm Pt wire, where the constant current is flowing, is successfully measured by the fabricated very-thin Pt/W thermoelectric element.