An insect-based BioFET as a bioelectronic nose

Insects are able to perceive volatiles released by damaged plants in order to find food sources or mating partners. In order to use the highly developed olfactory sense of insects for analytical purposes, the “biological nose” of insects has to be combined with some electronic instrument via a bioelectronic interface to yield a “bioelectronic nose”. In order to combine a field-effect-transistor (FET) with an insect antenna of the Colorado potato beetle (Leptinotarsa decemlineata) in an electrically and mechanically stable way, the bioelectronic interface was adapted to the needs of the insect antenna. A mobile biosensor system basing on the pre-adaptation method containing a biologically sensitive field-effect-transistor (BioFET) as sensor head was used for measurements of plant damage in a glasshouse under real world conditions. First measurements with the biosensor showed for (Z)-3-hexen-1-ol, a marker volatile for plant damage, a dynamic range of 6 orders of magnitude, a threshold of quantification of about 1 ppbv, a limit of detection (i.e., signal-to-noise ratio>3) of about 0.1 ppbv, and is able to detect down to 300 ag (Z)-3-hexen-1-ol/ml air in a 500 ml sample within a few seconds (ca. 50 ms raise time to 90% signal amplitude, ca. 5 s adaptation time after signal maximum). These characteristics were sufficient to distinguish single mechanically or beetle-damaged plants in background emissions of 1000 undamaged plants in the glasshouse.