More than 4000 articles have been published since 1990, describing
numerousapplications.Richand Myszka(2000,2001,2002,2003),Baird and
Myszka (2001)and Mehrvaret al.(2000)give overviewsin theirreviewarticles
aboutrecent developments.
The SPRtechnique has beenthe backbone of a verycommoncommercial
biosensor for biomolecular interaction analysis since 1990. Biacore AB
(Sweden)developedthis instrument,whichis nowthe platformfor diverse
applications± 90%of published optical biosensorresearch is performedby these
devices (Bairdand Myszka, 2001).
Piezoelectricbiosensors
Piezoelectric devices are mainlybasedon the detectionof a changeof mass
density, mostlyrepresentedby BAWand SAW, as described in section19.2.1.
Janshoff and Steinem(2001)givean overview aboutthe working principle of
these systemsin liquids. Owing to high energylossesby measurements in
liquids, the sensitivityof these devices is ratherlow comparedwithoptical
devices. Becauseof theiradvantages (see Table19.3)theyare still part of some
typicalbioanalyticalresearch topics.
Bacillus cereuswas detected by Vaughanet al.(2003)withlabel-free quartz
crystal microbalance(QCM)sensor witha detectionof about 104 cells/mL.
Mannelliet al.(2003)developeda DNApiezoelectricsensor for the detection of
genetically modified organisms (GMOs). La»nge et al. (2003) created an
immunosensor on the basisof a SAWdevice, whichwas able to monitor urease
binding at anti-urease-coated SAWdevicesin real timewithgoodresolution.
19.3 Common industrial applications and futuretrends
Sensors havea greatpotentialfor futureuse in the foodprocessingindustry for
process and quality control. The applicationareasare in the fieldof pathogen
detectionrelated to raw material, processing and qualitycontrolof finalproduct.
So far, mostof the sensors that havebeenimplementedin the foodindustry on
the production line havebeenfor the purpose of environmental monitoring of
hazardousgasessuchas hydrocarbons, ammonia and hydrogen sulphidethat
mayoccurduringthe production process.However, thesekindsof sensor,also
including physical sensors, provide informationon the performanceof the
process, whichin the bestcasemayindirectly contribute to controllingthe
hygienic qualityof the process,but doesnot provide directinformation on the
quality of the product being processed. For this purpose, chemical and
biosensorsare helpful, also withregard to theiron- and in-lineoptions.Since
most researchhas beenconducted underlaboratoryconditionstheseoptions
strongly dependuponthe application and the processsurroundings.
Twofundamentaltrendswill havethe strongest influence on applied research
in the fieldof sensortechniques,whichare strongly connected: because of
public opinionand resultingpoliticalactionsfoodsafety issues havebecomeone
298 Handbookof hygiene controlin the foodindustry