Thermocouple is a thermograph which uses Seebeck effect to measure the temperature. When two different metal make up a surround, the temperature difference between two combining site will cause electric current . So we use measure this electic current and then canculate the temperature.
In this figure, A and B are two different metal. When the temperature is different between 1 and 2, there will appear electric current. www.zhangpeng.info
Now we offten use sheathed thermocouple in industry field. These thermocouples is just put two kinds of metal in one pipe.
I have a idea to make new type of thermocouple. We just use the pipe to act as one metal and put the other metal in it then fill out the gap with MgO to insulate. If this idea come true, the thermocouple can be smaller.
This is my idea to make new type of themocouple. There are some problems. I think how to make it stable and live long it most important.