Detection of forest wildfires at early stages can significantly improve the success of fire fighting and thus it contributes to the damage and cost reduction. Surface deployed sensor networks linked to global nets are often regarded as technically simple options to achieve forest fire detection and progress monitoring. Straightforward solutions with sensor nodes continuously supplying telemetric information demand heavy duty power supplies and periodic service. They are relatively expensive and commonly not environmentally friendly. We have suggested and currently develop an early warning forest fire detection system based on inexpensive, dormant fire-activated detecting sensors and a number of monitoring nodes in a network configuration. Small deploy-and-forget type sensors contain a radio transmitter with recorded identity number, together with an inactive power element. When activated by high temperature of a developing wildfire, this element produces enough power to support the transmitter, broadcasting the unique identity code until the sensor is completely burnt. Monitoring nodes of such system stand by for sensor activation and forward the alarm information along the monitoring nodes network. Implementation of anti-collision transmission protocols in the sensors allows the monitoring nodes to keep track of fire development and progress. Monitoring nodes and nodes linking the forest fire detection and monitoring net to public networks can be made using conventional technology and utilizing existing communication networks. Thus significant efforts have been directed to the design of the primary sensors, designing them to be cost efficient and minimizing their environmental impact. Cellulose-based materials are widely used in the sensor construction to decrease its environmental impact and cost. The core of the sensor power element is made of laminated and screen-printed cellulose- based substrates. The power element is activated by a small amount of water, trapped in crystal hydrate salts in storage and released by elevated temperatures of the fire. These salt-based sensors can be manufactured in a rollto- roll manner, making them cost effective. Absence of any liquids or gels in the sensor construction will guarantee a good shelf time. © 2012 WIT Press.