Every year forest fires cause severe financial losses in many countries of the world. Additionally, lives of humans as well as of countless animals are often lost. Due to global warming, the problem of wildfires is getting out of control; hence, the burning of thousands of hectares is obviously increasing. Most important, therefore, is the early detection of an emerging fire before its intensity becomes too high. More than ever, a need for early warning systems capable of detecting small fires from distances as large as possible exists. A look to nature shows that pyrophilous "fire beetles" of the genus Melanophila can be regarded as natural airborne fire detection systems because their larvae can only develop in the wood of fire-killed trees. There is evidence that Melanophila beetles can detect large fires from distances of more than 100 km by visual and infrared cues. In a biomimetic approach, a concept has been developed to use the surveying strategy of the "fire beetles" for the reliable detection of a smoke plume of a fire from large distances by means of a basal infrared emission zone. Future infrared sensors necessary for this ability are also inspired by the natural infrared receptors of Melanophila beetles.

Purpose -Early detection of forest fires offers the chance to put the fire out before it gets out of control. The purpose of this paper is to look into nature and to learn how certain insects detect remote forest fires. A small group of highly specialized insects that have been called pyrophilous is attracted by forest fires and approaches fires sometimes from distances of many kilometers. As a unique feature some of these insects are equipped with infrared (IR) receptors, which in case of two species of jewel beetles (family Buprestidae) are used for fire detection. Design/methodology/approach -The paper has investigated the IR receptors of the pyrophilous beetles with various morphological techniques including scanning electron microscopy, transmission electron microscopy, neuroanatomy and the paper also investigated the thermo-/mechanical properties of the IR receptors by nanoindentation. Data were used for subsequent modeling of a biomimetic technical sensor. Finally, a macroscopic prototype was built and tested. Findings -This biological principle was transferred into a new kind of uncooled technical IR receptor. A simple model for this biological IR sensor is a modified Golay sensor in which the gas has been replaced by a liquid. Here, the absorbed IR radiation results in a pressure increase of the liquid and the deflection of a thin membrane. For the evaluation of this model, analytical formulas are presented, which permits the calculation of the pressure increase in the cavity, the deformation of the membrane and the time constant of an artificial leak to compensate ambient temperature changes. Some organic liquids with high thermal expansion coefficients may improve the deflection of the membrane compared to water. Originality/value -Results so far obtained suggest that it seems promising to take the photomechanic IR receptors of pyrophilous jewel beetles as models for the building of new uncooled IR sensors. The beetle receptors have been shaped by evolution since thousands of years and, therefore, can be considered as highly optimized sources of inspiration for new technical sensors suitable for remote fire detection. Definitions cuticle¼ exoskeleton of arthropods; consists of chitin fibres embedded in a protein matrix. Different layers can be distinguished: epi-, exo-, meso-and endocuticle (from outside to inside) dendrite/ dendritic region ¼ stimulus-receiving (signal-input) region of a neuron. endemic ¼ native and/or restricted to a certain area. haemolymph ¼ equivalent to blood in most invertebrates. lateral ¼ situated on the side. mitochondria ¼ "the cells power stations", in which biochemical processes of respiration and energy production occur. proprioceptor ¼ sensory receptor, receiving stimuli from within the body.sternite ¼ ventral abdominal segment. tonic response ¼ of a sensory neuron is proportional to the amplitude of a stimulus; phasic response is proportional to the change (1. derivation) of the stimulus amplitude; phasic-tonic response shows both components. ventral ¼ relating to the u...

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The infrared receptor (sensillum) of the beetle Melanophila acuminata is a highly sensitive infrared sensor. The well-known gas-filled Golay cell is a first approach to describe the working principle of such a sensillum. In contrast to the Golay cell the working fluid in a sensillum is a liquid. For the selection of the optimum fluid, water, hydrocarbons and air are compared. As a result hydrocarbons create a more than 4.5 higher deflection of the membrane. The gas-filled Golay cell uses a compensation leak to compensate ambient temperature changes. For the layout of the compensation leak an analytical solution was derived.