Chemical Sensors & Biosensors

Contact Dr. Necati Kaval for information and scheduling for the Chemical Measurement Instruments. (513) 556-9201. (email)

  • Environmental Scanning Electron Microscope with EDS system for X-ray mapping
    The Scanning Electron Microscope (ESEM) and an associated X-Ray EDX system are capable of element mapping of acquired images. The FEI XL30 ESEM and EDX system are capable of normal high vacuum SEM operation as well as low vacuum ESEM mode operation with added water vapor for samples that cannot be measured at high vacuum or that need to be hydrated. In ESEM mode it is possible to look at samples that are non-conductive such as biological samples. The ESEM instrumentation is available for use from 9:00am - 5:00 PM Monday through Friday.
  • Microchip Laser Induced Fluorescence System
    The facility operates a custom-built Laser Induced Fluorescence (LIF) detection system for microchip capillary electrophoresis measurements. A Nikon TE 2000 epifluorescence microscope has been equipped with a PMT module, a CoolSnap HQ CCD camera, a low current preamplifier, and a PCI DAQ card for fluorescence detection. Four laser excitation sources are available (20 mW, 403 nm; 50 mW, 488 nm; 20 mW, 532 nm; 35 mW, 633 nm), as well as a filtered xenon arc lamp.
  • Thermogravimetric Analysis and Differential Scanning Calorimeter (TGA/DSC)
    The facility contains a NETZSCH STA 409 PC Luxx TGA/DSC instrument. This instrument runs in a temperature range of 25°C to ~1200°C under various atmospheres, typically Ar. Information pertaining to thermal stabilities, gas sorption, glass transitions and melting points of various materials can be obtained from the instrument. The TGA/DSC is available from 9:00 AM - 5:00 PM every Monday through Friday.
  • Surface Plasmon Resonance System
    The facility contains a BIACORE 2000 Surface Plasmon Resonance instrument. The instrument uses the optical phenomenon of surface plasmon resonance (SPR) to monitor the physical interactions of unaltered, active biological molecules in real time. The SPR response is correlated to optical changes on a sensor chip surface. This signal is monitored continuously so that chemical interactions between biomolecules can be studied in real time.
  • Spectroscopic Ellipsometry
    Determination of the thicknesses and optical constants (n-refractive index, k-extinction coefficient) of thin films can be obtained using the spectroscopic ellipsometer (J.A. Woollam Inc.). The practical range of thickness for non-absorbing films that can be accurately measured is approximately 10 nm to 10 μm (for optically absorbing films (semiconductors, metals, etc.) this range is reduced). Determination of the optical constants for absorbing materials is possible using the reflection spectroscopy regardless the thickness of the specimen.
  • Electrochemical Quartz Crystal Microbalance (EQCM)
    The Electrochemical Quartz Crystal Microbalance (EQCM, Stanford Research Systems) is capable of measurements of microgram-range masses deposited at the crystal surface. The instrument uses a quartz crystal with gold electrodes operating at 5 MHz. Mass adsorbed on the crystal surface changes the fundamental frequency of the crystal which is, in turn, proportional to the adsorbed mass. Electrode surface kinetics under applied potential can be studied using the combination of the mass measurement and the associated electrochemical protocol.
  • Fluorescence and UV/vis Spectrophotometers
    The facility has Cary Eclipse fluorescence and Cary 50/Bio UV/Vis absorbance spectrophotometers, both from Varian which are controlled with a single computer. The Varian Cary Eclipse fluorescence spectrophotometer offers high performance measurements in fluorescence, phosphorescence or chemi/bio luminescence modes. The light source is a xenon flash lamp which provides excellent sensitivity. The instrument collects 80 points/second which allows it to log fluorescence kinetic data. Besides the conventional single cell holder, the instrument has a temperature controlled multi-cell holder and a variable angle solid sample holder. The Cary 50 also incorporates a xenon flash lamp enabling it to offer many advantages over traditional UV-Vis spectrophotometers. The intense Xe lamp allows the use of micro cells. The Xenon lamp flashes only when acquiring a data point, so photosensitive samples are not exposed to light during idle periods of time. The instrument can measure samples up to 3 Abs units between 180 nm and 1100 nm.
  • Electrochemistry Equipment
    Electrochemistry equipment in the facility includes two BAS 100B electrochemical analyzers, two BAS Epsilon EC and several CV-27 potentiostats. BAS 100B electrochemical stations are capable of cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry/polarography, hydrodynamic techniques, rotating disc electrode operation. Epsilon EC and CV-27 are more portable instruments which can be coupled to other instruments such as spectrophotometers for experiments which require simultaneous electrochemical studies.
  • JANDEL Four-point Probe
    The instrument is dedicated to measurements of electrical resistivity of samples. The Four-Point-Probe consists of a vertically adjustable probe head mounted on a horizontal platform and a constant current source combined with a digital voltmeter. This equipment can measure the resistivity of samples such as metals, silicon wavers, conductive polymer films, etc.