Electrochemical sensing at Acreo - electrochemistry and impedance Anatol Krozer, Sensor Systems, Göteborg

1. Electrochemicalsensing at Acreo- electrochemistry and impedanceAnatol Krozer, Sensor Systems, Göteborg Hudiksvall (Optical fibers, R&D and production) Kista, Stockholm (Optical Fibers R&D, Nano, SiC) … Norrköping (Printedelectronics) Göteborg, Sensor Systems

2. Acreo, Sensor Systems - peopleinvolved Dag Ilver Christer Johansson Kristina Fogel Jakob Blomgren John Rösvall Torbjörn Pettersson Fredrik Ahrentorp AK Andrea Astalan Cristina Rusu Boris Stoev Lei Ye, Keichii Yoshimatsu, … - AppliedBiochemistry, Lund Univ Kristina Reimhult, LuSun, …

3. Fluid responsetovariablevoltage - global vs local VAC • Mobile ions/chargedparticles in a liquidacttoscreenaway an externalelectricfield→ charge separation → charge pile upclosetoelectrodes. At mostionicconcentrations of interest the electricfield, E, inside the liquid is ≈ 0 in equilibrium. • Typical screening distances at ionicstrengths of interesthereare < µm. The ion excess at electrodes (the double layer) inducescapacitances µF. • Ioniccurrent in a fluid, I, is given by: – concentration, – effectiveion charge and – ionmobility. • Variableexternalvoltage→ Iresponse lags behindVduetosizeeffects. Contributionduetoionic/particle motion decreaseswithfrequency. IAC

4. Local (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 - Glutamicacid; C - Cystein; K - Lysine; H - Histidine; Y – Tyrosine pH response Peptidelayerthickness < 50nm • Thicknesschanges of fewnmcan be detected • Detection of small changes of ionconcentration • Quantitativedetection by data fitting

5. Twoapproaches: • plane electrodes: f < 1MHz • Planar coil: f  5MHz Global: aging of lubricants for cuttingtoolsat Volvo Skövde plant Addinglubricationoil Lubricant Planparallel electrodes Planar coil Vinnova grant – waterqualitymonitoring ”Sensation”

6. Local: Biofouling - capacitivedetection Similar principle applies for planar electrodesfacingeachother (seepreviousslide), for the interdigitated finger configuration or for planar coils as shownhere. Buffer MIP MIP MIP MIP MIP MIP MIP MIP Passive polymer matrix Passive polymer matrix - + + Si wafer/glas + - Planar electrodes: Sensingdepth is of the order of electrode – electrodedistance. Si wafer/glas Example: Milk handling - biofilm

7. AFM Molecularlyimprinted polymers on microelectrodes • Polymers withmolecular ”memory” ”artificialantibodies” • Applicablemainlytomolecules < kDabutimprints of peptides, proteins and evenmicroorganismsare under development • Robust (shelflife – years) • Toxins, eg., marine toxins or volatile mouldproducts • Narcotics • Chemicalwarfare agents • Explosives • Peptides • Pharmaceuticalwaste • Tannins, coffeines • Sugars, (sorbitol, glucose) 170nm S-MIP in PET 2,4µm S-MIP particles in PET SECURITY - Emergency Support System no: 217951

8. Zephyr - measuringioncontent and moisture of earth Similarresults for fits with less datapoints Water supply to PC Resultscomparedwith the commerciallyavailable sensor • Drawbacks (lack of electronics for fieldconditions) • measuresonlyImpedanceamplitude! Phase info is lost (but Kramers-Krönig relations areoftenapplicable) • Measuresonly at descretenumber of frequencies (here at 2 frequencies) • →requires extensive calibrations & modelling • Electronics underway (see eg., http://sciospec.de/cms/home) Grant ENV.2012.6.3-1: ZEPHYR no: 308313

9. Zephyr - Improvedmodel for soilmeasurements Grant ENV.2012.6.3-1: ZEPHYR no: 308313

10. Coil as an electriccomponent R=(R0 + 2p fL0’’) L=L0 (1+ ’) f < f0 Inductor f << f0 resistor f > f0 Capacitance R C L R0 Frequency • ’ and ’’ – in-phase and out-of-phase electric susceptibilities (polarisabilities) of the of the surrounding media •  is the coupling coefficient to the measured media (eddy currents) • Eddy currents (Garcia-Martin etal., Sensors (2011) vol. 11, pp. 2525-2565) → R  f2; L  f2 • Typical skin depth is  0.2 m at 1 MHz and resistivity of 0.5 m (urine or physiological buffers) → in practice full penetration at most geometries • Impedance in liquids → substitute C by constant phase element, CPE 

11. Use of planar coilstofollow the kinetics of chemicalbinding (patent pending) Molecularlyimprinted polymers - MIPs Doseresponse – target: propranolol Coilscoveredwith a dense ML of imprinted & non-imprintedbeadsusingmussel adhesive proteins as a ”glue” (patent pending) Fit quality! SECURITY - Emergency Support System no: 217951

12. Practical implementation – battery-poweredautonomous system Temperaturestabilisation MIP NIP Vac R1 R2 - + Fully automatised and energizedWheatstone bridge configurationtodetectchanges of abs(ZMIP) – abs(ZNIP) SECURITY - Emergency Support System no: 217951

13. Q [Asec/cm2] Molecular Imprinting of sugars (sorbitol)– cyclic voltammetry (CV) Film preparation • Clean electrodes: H2O2/HNO3/H2O, UV-ozone & CV in 1M sulphuricacid • Polymerisation in 10 mMacetatewith monomer (54 ml 100 mg/ml) and 5 mMsorbitol • Deposit polymer by CV. Lowcurrentimplies the formation of a continuous MIP film. Home-made electrochemical cell with an option for surface plasmon resonance detection MIP performance by electrochemical impedance The effect of Au cleannesson MIP deposition MIP deposition • Film adhesion & MIP performance • Insufficient Au surface cleanness • Film stability • Poor sensitivity of impedance measurements → Use Imego designed microelectrodes Q [Asec/cm2] Anatol Krozer /20090121/

14. Integratedprinteddisposable biosensor – Acreo PrintedElectronics Amperometry, potentiometry or impedance On-board signal processing First demonstrator Printed biosensor Printed battery Printed circuitry Printed display Chip Final goal Current status Demonstrated with glucose sensing

15. Acreo Printed Electronics – manufacturing greenhouse • 500 m2 • 6 Printing machines screen, flexo, (2 R2R) • Equipment for test and inspection • Equipment for ink development • Offices • Meeting places • Manufacturing processes • 5 R2R single component processes • 4 sheet integrated systems processes • 1 R2R integrated system process (under development) • Activities • Prototype design • Product development • Production • Technology transfer • Workshops Collaborationwith the Linköping University

16. The end! • Impedance is by far not the only area of ourinterest! Pleasecontactme for further information aboutourotheractivities. Theseinclude: • MEMS and their signal analysis - MEMS systems • Magnetism & magneticnanoparticles • Optical sensors – fluctuations, fluorescense, FRET, etc. • Weapplytheseto: • Inertialnavigation • e-health and e-sports • Immunoassayplatforms • Waterqualitymonitoring (rawwater, industrialwaste, urban water systems, etc.) • Bacteria detection and living sensors • Agriculture and cattle • Youname it! • Weaim at cheapbutfullyautomatized systems • Wegladlywelcomeindustrial and academiacont(R)acts and collaborations, and common fundingapplications!

18. Additionalactivities

19. Zephyrmeasuringion and watercontentusingwrappedcoils • Bothinductance and capacitancechanges • It is possibletoextractconductivity ( ioncontent) and capacitance ( watercontent) Grant ENV.2012.6.3-1: ZEPHYR no: 308313

20. Urea in tapwater 6 10 -2000 -27 5 10 |Z| x104 4 -2 10 0 2,5 5 3 10 Z'' MQ 2 Tap water 2 -1000 -100 Tap water 1 MQ 3 Tap + 5% urea -50 theta 0 -1 0 1 2 3 4 5 6 0 10 10 10 10 10 10 10 10 0 2000 4000 6000 8000 Frequency (Hz) Z' Requires Differential ImpedanceAnalysis

21. Ourcollaborators in Bulgaria – differential impedanceanalysis • Water-in-oil • Oilageing • Urea • Construction of a continuous, virtually care-free and self-calibrating equipment is possible • Although we presented data only up to 1 MHz we do have experience with experiments up to few tens of GHz. The latter may allow • remote sensing • ”chemical specificity” • Use of several narrow frequency measurement intervalls decreases equipment cost and enhances specificity • Software development and signal analysis are important

22. Waste from the wastetreatment plant at Borås Beakerwith sedimented waste (after 0,5h) and electrodes

23. Monitoring fluid level Coil area: 50mm x 50mmMid openarea: 10mm x 10mmPitch = line width = 0,2mm • Probedepth≈width of the (pitch + current line) • Similarsensitivity for 3-dim coil and for coilswrappedaround the polymer chamber from the outside. • Resonancedamping (quality, Q-factor, decrease) depends on the ionicconcentration. For nakedcoil wires and ionicstrengthstypical of urine Q is low, Q  1 • Dampingdecreasesconsiderablywhen the coil is covered by thinbutdenseinsulatinglayer

24. COILS

25. Planparallella elektroder Två olika representationer av mätdata 8 Ny vätske”batch” 1 9 • Slutsatser: det går att mäta något större (?) skillnader mellan de olika skärvätskorna även för den nya batchen jämfört med skillnadetr vid högre frekvenser • Modellering behövs

26. 800 Conductivity ioncontent 600 100 Z'(Ohm @ 10 kHz) 400 80 200 60 Abs (Z) (Ohm) Value 40 102 R RC 3.1188e-8 Capacitans watercontent 20 a 0.99199 200 0 105 107 Capacitans (pF @ 3MHz) f (Hz) 100 0 0 40 80 120 Watercontent (ml)