For testing our circuit it has 3 parts peltier module, volt boosting circuit and LED. 

When we put our hand on Peltier. With the hand of our heat peltier module produce about 30mv to 40mv. Then volt boosting circuit take 30mv to 40mv from peltier and convert it into 2.5v and send it to LED. When LED receives 2.5V it starts running.