Biomimetic gas sensors for large-scale drying of wood particles

摘要

The sensitivity and selectivity of insect antennae are evolutionary tuned to specific needs of the insect. The Australian pyrophilic beetle Merimna atrata needs freshly heated wood to bring up its offspring and, consequently, shows a very high sensitivity to volatiles specific for wood-fires and heated wood. Volatile organic compounds released by wood particles heated at different temperatures were collected. Parallel trace analytical examination and antennal responses of the pyrophilic beetles to volatiles released by the wood reveal a highly differentiated detection system of these insects for early and late products of wood fires. This enabled a selection of marker compounds used by insects since several million years for the discrimination of different stages of wood fires. In the industrial production of engineered wood such as particle boards, wooden particles are dried in large-scale high temperature dryers. Air temperatures between 150-600°C are essential for the required material flow in the particle board production. Despite the resulting energy-efficiency of high temperature drying, high temperatures are avoided because of the increased risk of spontaneous combustion. Losses in productivity caused by fire have a strong impact on the whole production system. In order to raise the drying temperature without risking a fire, it is important to develop a monitoring system that will reliably detect early fire stages by their characteristic volatile pattern. Thus, perception filters and evaluation algorithms of pyrophilic insects can provide blue prints for biomimetic gas sensors for large-scale drying of wood particles. Especially tungsten oxide sensor elements exhibit a high sensitivity to some of the key substances. Their high sensitivity and selectivity to terpenes and aldehydes in combination with high sensitivity and selectivity of tin oxide sensor elements to hydroxylated and phenolic compounds, both showing low cross-reactivity with water and carbon monoxide, mimic highly efficient biological fire detection systems.