Infrared receptors in pyrophilous (“fire loving”) insects as model for new un-cooled infrared sensors

Abstract

SummaryBeetles of the genus Melanophila and certain flat bugs of the genus Aradus actually approach forest fires. For the detection of fires and of hot surfaces the pyrophilous species of both genera have developed infrared (IR) receptors, which have developed from common hair mechanoreceptors. Thus, this type of insect IR receptor has been termed photomechanic and shows the following two special features: (i) The formation of a complex cuticular sphere consisting of an outer exocuticular shell as well as of a cavernous microfluidic core and (ii) the enclosure of the dendritic tip of the mechanosensitive neuron inside the core in a liquid-filled chamber. Most probably a photomechanic IR sensillum acts as a microfluidic converter of infrared radiation which leads to an increase in internal pressure inside the sphere, which is measured by a mechanosensitive neuron.A simple model for this biological IR sensor is a modified Golay sensor in which the gas has been replaced by a liquid.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.

Paradigms for biologically inspired design

“…Pyrophilous (fire-loving) insects utilize a mechanical sensor that detect very small volume fluctuations caused by infrared radiation 60 . This can be mimicked to for passive, i.e.…”

Sensory system in the wings red palm weevil Rhynchophorus ferrugineus

“…Probing of the substrate surface with antennae always occurs before feeding and egg-laying in R.palmaram (Said et al, 2003). Whereas the olfactory receptors for smoke are located on the antennae, the IR receptors are housed in extra-antennal sensory organs, which can be found on the thorax or on the abdomen (Klocke et al, 2011). Most insects have IR receptors in wings.…”

Infrared receptors of pyrophilous jewel beetles as model for new infrared sensors

“…The maximal (central) deflection y max of the circular membrane depends on all parameters mentioned above and the amount of IR energy absorbed by the liquid. It can be calculated as a function of the factor V (Klocke et al, 2011):…”