个人简介
Postdoctoral Associate Massachusetts Institute of Technology, 1990-1992 Ph.D. University of Illinois at Urbana Champaign, 1990 B.S. University of Utah, 1985
研究领域
micro electro-analytical devices
Analytical and Bioanalytical Chemistry The unifying theme of our research program is the development of multifunctional, miniaturized analytical devices with integrated components on a single substrate. Such “labs-on-a-chip” have promise in revolutionizing sample preparation, chemical analysis, and chemical synthesis. A wide variety of applications are possible, including on-site analysis of environmental samples, analysis of key components in body fluids at the doctor’s office or at home, and synthesis and purification of materials on a small scale. To carry out this work, our activities are interdisciplinary in nature, often requiring scientific collaborations with other chemists, chemical engineers, electrical engineers, food scientists, and industrial partners. More specifically, we investigate chemistry in the limit of ultrasmall volumes (nanoliters to picoliters), near materials having ultrasmall features (submicron patterning), and with new approaches to moving solutions around to carry out sequential reactions in an automated way (microfluidics). In addition, we study the means of interfacing inorganic electrodes and micro/nanostructures with assemblies of organic and biologically- important molecules. Computer simulations are used as a complementary tool to further investigate these systems. Analytical instrumentation that is essential to this work includes electrochemistry, polarization-modulation Fourier transform infrared spectroscopy (PM-FTIR), surface probe microscopy (e.g. atomic force microscopy), X- ray photoelectron spectroscopy, and mass spectrometry. Several projects also involve hands-on experience with microlithographic techniques. Ultrasmall Electrochemical Devices. Essentially, smaller (both in size of device and of sample) is better, more sensitive, and provides better detection limits! A variety of procedures that were developed for silicon wafer-based, integrated circuit electronics fabrication are used to construct microscopic devices with submicron dimensions. We have also developed a simple and inexpensive fabrication method for devices on flexible substrates that are capable of self-contained electrochemistry from microliter to picoliter-sized samples. For example, cavities of various geometries can be formed into layered materials of conductor and insulator, each 100’s of angstroms to several 100’s of microns thick. This yields nanometer to micron-sized features on the walls of the cavities. Such devices provide multiple functionality both laterally (parallel to the plane of the substrate) and vertically (perpendicular to the plane of the substrate). If several of the layers are conducting, then many electrodes may reside in a very small space. The combination of the close proximity of these electrodes and the ability to analyze ultrasmall samples in the small space provides unique capabilities that are not possible with traditional electrochemical cells. We are using this basic construct to develop fast microelectrochemical immunoassays (on volumes less than 1µL) and to investigate new approaches for in vivo analysis of neurotransmitters. A New Approach to Microfluidics. We have developed a new method for stirring on a picoliter scale, moving solutions from one site to another on a chip for processing, and forcing solvent through channels to carry out separations of mixtures. It involves applying a phenomenon, magnetohydrodynamics (MHD), that is better known in the astrophysics of plasmas and liquid metal pumping than it is in analytical chemistry. MHD involves three physical fields that are at right angles to each other: electric, magnetic, and flow. Application of an electric and magnetic field in small channels or microscopic reactor or sensor vessels containing aqueous or non-aqueous solution results in controlled flow or stirring. We are investigating the fundamental properties of MHD and how MHD may be used in a wide variety of analytical chemistry applications to enhance sensitivity, detection limits, provide fast reactions, and carry out complete sample manipulation, separation, and detection on an ultrasmall volume scale. Patterning Organic Materials using Applied Potentials. Potential-dependent modification provides a means to specifically modify different submicron- and micron-sized electrodes in various geometries and locations with organic molecules so that arrays of chemical sensors may be constructed. An emphasis of this work is understanding the influence of electrochemical environment and reactions of the organic molecules with the surfaces of the electrodes under potential control. Some research in this area focuses on gold surfaces modified with self-assembled monolayers (SAMS) of organothiols. We have ongoing projects on the stability of SAMs as a function of potential, time, conditions, environment, and solvents. The products formed are being characterized, as are the surface and solution mechanisms that are responsible for any instability. Interfacing Organic Materials to Inorganic Micro and Nanostructures We are incorporating the natural selectivity of biologically-important molecules into thin films to discriminate electrochemical signals for micro and nanoscopic sensors. This involves the design and construction of a well-defined biomembrane-like layer not only on electrode surfaces, but also across microfabricated cavities, essentially encapsulating self-contained electrochemical devices inside. New sensing materials are being synthesized from thin organic films of mixed hydrophobic and hydrophilic properties that are formed by SAMs and phospholipids. These materials form the basis of biomimetic membranes and artificial biological cells.
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Sahore, V. and I. Fritsch, Microfluidic rotational flow generated by redox-magnetohydrodynamics (MHD) under laminar conditions using concentric disk and ring microelectrodes. Microfluid. Nanofluid., 2015. 18(2): p. 159-166.
Hu, M. and I. Fritsch, Redox Cycling Behavior of Individual and Binary Mixtures of Catecholamines at Gold Microband Electrode Arrays. Anal. Chem. (Washington, DC, U. S.), 2015: p. Ahead of Print.
Sahore, V. and I. Fritsch, Redox-Magnetohydrodynamics, Flat Flow Profile-Guided Enzyme Assay Detection: Toward Multiple, Parallel Analyses.Anal. Chem. (Washington, DC, U. S.), 2014. 86(19): p. 9405-9411.
Scrape, P.G., et al., Redox-magnetohydrodynamics for microfluidic control: remote from active electrodes and their diffusion layers. J. Electrochem. Soc., 2013. 160(6): p. H338-H343.
Sahore, V. and I. Fritsch, Flat Flow Profiles Achieved with Microfluidics Generated by Redox-Magnetohydrodynamics. Anal. Chem. (Washington, DC, U. S.), 2013. 85(24): p. 11809-11816.
Gao, F., et al., 3D Imaging of Flow Patterns in an Internally-Pumped Microfluidic Device: Redox Magnetohydrodynamics and Electrochemically-Generated Density Gradients. Anal. Chem. (Washington, DC, U. S.), 2013. 85(9): p. 4414-4422.
Aggarwal, A., M. Hu, and I. Fritsch, Detection of dopamine in the presence of excess ascorbic acid at physiological concentrations through redox cycling at an unmodified microelectrode array. Anal. Bioanal. Chem., 2013. 405(11): p. 3859-3869.
Weston, M.C., et al., Maximizing Flow Velocities in Redox-Magnetohydrodynamic Microfluidics Using the Transient Faradaic Current. Anal. Chem. (Washington, DC, U. S.), 2012. 84(21): p. 9402-9409.
Weston, M.C. and I. Fritsch, Manipulating fluid flow on a chip through controlled-current redox magnetohydrodynamics. Sens. Actuators, B, 2012. 173: p. 935-944.
Ensafi, A.A., Z. Nazari, and I. Fritsch, Redox magnetohydrodynamics enhancement of stripping voltammetry of lead(II), cadmium(II) and zinc(II) ions using 1,4-benzoquinone as an alternative pumping species. Analyst (Cambridge, U. K.), 2012. 137(2): p. 424-431.
Cheah, L.T., et al., Evaluation of heart tissue viability under redox-magnetohydrodynamics conditions: Toward fine-tuning flow in biological microfluidics applications. Biotechnol. Bioeng., 2012. 109(7): p. 1827-1834.
Sen, D., et al.,Investigation of transient redox electrochemical MHD using numerical simulations. Int. J. Heat Mass Transfer, 2011. 54(25-26): p. 5368-5378.
Williams, C.R. and I. Fritsch, Automated printing of electrochemical immunoassay microarrays: studies of conditions affecting alkaline phosphatase enzyme label activity. ECS Trans., 2010. 28(21, Student Posters (General)--217th ECS Meeting, 2010): p. 19-33.
Weston, M.C., C.K. Nash, and I. Fritsch, Redox-Magnetohydrodynamic Microfluidics Without Channels and Compatible with Electrochemical Detection Under Immunoassay Conditions. Anal. Chem. (Washington, DC, U. S.), 2010. 82(17): p. 7068-7072.
Weston, M.C., M.D. Gerner, and I. Fritsch, Magnetic Fields for Fluid Motion.Anal. Chem. (Washington, DC, U. S.), 2010. 82(9): p. 3411-3418.
Lewis, P.M., et al., Signal Amplification in a Microchannel from Redox Cycling with Varied Electroactive Configurations of an Individually Addressable Microband Electrode Array. Anal. Chem. (Washington, DC, U. S.), 2010. 82(5): p. 1659-1668.
Fakunle, E.S. and I. Fritsch, Low-temperature co-fired ceramic microchannels with individually addressable screen-printed gold electrodes on four walls for self-contained electrochemical immunoassays. Anal. Bioanal. Chem., 2010. 398(6): p. 2605-2615.
Ensafi, A.A., A.C. Ring, and I. Fritsch, Highly Sensitive Voltammetric Speciation and Determination of Inorganic Arsenic in Water and Alloy Samples Using Ammonium 2-Amino-1-Cyclopentene-1-Dithiocarboxylate. Electroanalysis, 2010. 22(11): p. 1175-1185.
Ensafi, A.A., Z. Nazari, and I. Fritsch, Highly sensitive differential pulse voltammetric determination of Cd, Zn and Pb ions in water samples using stable carbon-based mercury thin-film electrode. Electroanalysis, 2010. 22(21): p. 2551-2557.
Anderson, E.C., M.C. Weston, and I. Fritsch, Investigations of Redox Magnetohydrodynamic Fluid Flow At Microelectrode Arrays Using Microbeads. Anal. Chem. (Washington, DC, U. S.), 2010. 82(7): p. 2643-2651.
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