Heat-triggered high-performance thermocells enable self-powered forest fire alarming

Harvesting heat from fire itself to power wireless sensor networks has the potential to realize effective detection and alarm for forest fires. Thermocell based on thermogalvanic effect offers an inexpensive and scalable way to heat-to-electricity conversion but challenged by its low performance. We demonstrate a boosted thermogalvanic effect by introducing concentration gradients into a thermocell, achieving a one order magnitude enhancement of output up to 45.9 W m−2. Using a heat-triggered membrane as start switch, a thermocell which can hibernate in peacetime and awaken when fire, is further obtained. A proof-of-concept device integrated by five units successfully detects the precombustion and open fire to synchronously generate a high voltage of ~2 V for driving alarm. This system shows promise for combating the global increasing forest fires.