classificationoptions.Further classifications are the wayof identification' and scaling ofbioelementintegration'.
Advantagesof thesedevicesare relatively rapidassay times,low cost,great
selectivity,littlesample consumption;theycan be miniaturised and integrated
into one chip,and easyhandling. Disadvantagesincludethe dependencytowards
pH, temperature, limited lifetimes and other general conditions. As a
consequence their superiorselectivity (compared withchemical sensors) is
limited by their biological component which requires mild conditions
(O'Connell and Guilbault,2001a). This also includes the relatively short
lifetime of biosensors comparedwithconventionalinstrumentation. Because of
these specificpremises it is important to considerthe following aspects:
∑ Whichbioreceptor±transducercombinationwithwhichimmobilisationmethod.
∑ Contamination risk biosensor±sample hostsystem.
∑ The packagingof the sensor system(e.g.physicalrobustness).
∑ Requiredmeasurementrangeand linearity.
∑ User-friendlymaintenance.
Although the biosensorfoodpathogentestingmarketwas expected to growto
$192millionby 2005(Alociljaand Radke,2003),new developments are mainly
driven byin vivoapplicationsfor medical diagnosis.As a consequence, new
developmentsdo not find intermediate use in the agriculturaland foodindustry.
A list of companiesproducing biosensorsfor foodcontrolis givenby Kress-
Rogers and Brimelow(2001).Table19.3 providesan overview of advantages,
disadvantagesand application examples of the differentbiosensorsystems.
Fig. 19.3 Overview:classificationof biosensorsby theirtransductionelement
(electrochemical,thermal,optical,piezoelectric)or theirbiologicalelement(metabolism,
immuno,affinity,catalytic).
294 Handbookof hygiene controlin the foodindustry