WT brochure spr - Metrohm

THE TECHNIQUE- Maximum flexibility -THE SPR PRINCIPLESurface plasmon resonance occurswhen p-polarized light hits a gold layerat a certain angle under conditions oftotal internal reflection. An evanescentwave is generated and the energy isabsorbed by the free electrons in the goldlayer, generating resonance plasmonsand causing a reduction in the intensityof the reflected laser light.Since molecules are immobilizedon the gold surface, the refractive indexchanges, altering the angle at which theplasmon effect occurs.Optical unitThe Autolab SPR instruments usea scanning mirror to alter the angle ofincidence of the laser light. The mirrorscans 4 degrees at a certain offset angle,with a frequency of 76 Hz.The minimum in reflectionintensity, known as SPR dip, is detectedautomatically and plotted as a relativeSPR angle in the software. The offsetangle can be manually controlled witha spindle, providing a large dynamicrange.The high scan frequency results inlow noise measurements. The laser spothas an area of 2 mm 2 on the sensorsurface. Measured data will be anaverage of all events in that area.This has the advantage that anyinhomogeneity in, or defects of any ofthe additional layers on top of the goldsurface will be eliminated.SubstratesEco Chemie provides standardsensor disks: bare gold substrates madeof BK-7 glass with 48 nm of golddeposited on a thin layer of titanium.The low cost sensor disks areplaced on a retractable slider with ahemicylinder (also BK-7). To increasecompatibility, a special slider formeasurements on Biacore sensorchipsis available.The range in refractive indices ofthe sample solution under study canbe extended by using different types ofglass hemicylinders and substrates.CuvetteExcept for the diameter of thecuvette and the geometry of the needle,the following parameters can becontrolled by the user:● Mixing volume● Speed or frequency of mixing● Distance of the pipette tip/needle tothe sensor surface● Volume of the solution in the cuvette● Viscosity of the solution● Temperature of the solutionThis makes the instrument verysuitable for fundamental research. It isalso possible to use custom-builtcuvettes and/or cuvettes of differentmaterials.The ESPRIT and SPRINGLE havea unique electrochemical cuvette thatallows measurements on a 3-electrodesystem;● Fixed contact point tothe gold layer of thesensor disk (workingelectrode)● Reference electrode,which is replaceable● Counter electrode isa fixedPlatinumelectrodeLiquid handling unitSample handling can be donemanually, semi-automatic or fully automatic.In the Autolab ESPRIT, the twochannels of the cuvette use independentsyringe pumps to assure reproducibleexperimental conditions.Fully automaticThe autosampler is controlled bythe liquid handling tool in the software.Samples are taken from the microliterplate and injected in the cuvette. Theautomatic control allows the user to runmeasurements continuously.The software has predefined rackcodesfor different kinds of microliterplates, but it is also possible to definecustom-made sample holders.Semi-automatic controlThe sample is aspirated in theneedle/pipette tip or pipetted in thecuvette manually.Other liquid handling functionalitylike dispensing, draining, washing,mixing of sample and measurement isperformed automatically.Manual controlAfter the sample is pipetted intothe cuvette, all following steps likemixing, draining, washing, starting ofmeasurement, rinsing etc. are controlledmanually from the software with asimple mouse click.Autolab SpincoaterThe Autolab Spincoater is anaffordable tabletop spin coating systemthat can be used to coat uniform layersof for example polymers or metal oxideson a substrate.The system has a bowl with adiameter of 13.5 cm. Rotation speed canbe controlled manually from 100 - 10,000rpm with an accuracy of 2 rpm in stepsof 100 rpm.SPECIFICATIONS AUTOLAB SPINCOATER● Standard sample size● Motor speed range● Manual speed setting● Acceleration/deceleration25 mm ∅ disk100 - 10,000 RPM100 - 10,000 RPM in 100 RPM steps4,000 RPM/sPAGE 5