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Electrochemical sensing at Acreo- electrochemistry and impedanceAnatol Krozer, Sensor Systems, Gteborg

Kista, Stockholm (Optical Fibers R&D, Nano, SiC) Norrkping (Printed electronics)Hudiksvall (Optical fibers, R&D and production)Gteborg,Sensor SystemsAcreo, Sensor Systems - people involved

Lei Ye, Keichii Yoshimatsu, - Applied Biochemistry, Lund UnivKristina Reimhult, Lu Sun, Cristina RusuFredrik AhrentorpJakob BlomgrenChrister JohanssonKristina FogelDag IlverAndrea AstalanTorbjrnPetterssonBoris StoevJohn RsvallAKFluid response to variable voltage - global vs local VACIACLocal (at electrodes): artificial biofilm self assembled pH sensitive peptide monolayer

Designed, pH sensitive, thiol terminated peptides well known adsorption properties on the gold surface dense and insulating monolayer is formedC linear = CKHEYKHEYKHEYKHEYKEHEHEHH (-COOH)E - Glutamic acid; C - Cystein; K - Lysine; H - Histidine; Y TyrosinePeptide layer thickness < 50nmThickness changes of few nm can be detectedDetection of small changes of ion concentrationQuantitative detection by data fitting

pH responseGlobal: aging of lubricants for cutting tools at Volvo Skvde plantPlanparallel electrodesPlanar coil

Adding lubrication oilLubricantTwo approaches: plane electrodes: f < 1MHzPlanar coil: f 5MHz Vinnova grant water quality monitoring SensationLocal: Biofouling - capacitive detection

Similar principle applies for planar electrodes facing each other (see previous slide), for the interdigitated finger configuration or for planar coils as shown here.Planar electrodes: Sensing depth is of the order of electrode electrode distance.MIPMIPMIPPassive polymer matrixMIP+Si wafer/glas+-BufferMIPMIPMIPPassive polymer matrixMIPSi wafer/glas-+Example: Milk handling - biofilmMolecularly imprinted polymers on microelectrodes

Polymers with molecular memory artificial antibodiesApplicable mainly to molecules < kDa but imprints of peptides, proteins and even microorganisms are under developmentRobust (shelf life years)Toxins, eg., marine toxins or volatile mould productsNarcoticsChemical warfare agentsExplosivesPeptidesPharmaceutical wasteTannins, coffeinesSugars, (sorbitol, glucose)

AFM170nm S-MIP in PET

2,4m S-MIP particles in PET

SECURITY - Emergency Support System no: 217951

to PCWatersupplyZephyr - measuring ion content and moisture of earth

Results compared with the commercially available sensorDrawbacks (lack of electronics for field conditions)measures only Impedance amplitude! Phase info is lost (but Kramers-Krnig relations are often applicable)Measures only at descrete number of frequencies (here at 2 frequencies) requires extensive calibrations & modelling

Electronics underway (see eg., http://sciospec.de/cms/home)

Similar results for fits with less datapoints

Grant ENV.2012.6.3-1: ZEPHYR no: 308313 Zephyr - Improved model for soil measurements

Grant ENV.2012.6.3-1: ZEPHYR no: 308313 Coil as an electric componentRLCFrequencyR0f < f0 Inductorf > f0Capacitancef