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Defining The Value Of Injection Current And Effective Electrical Contact Area For Egain-Based Molecular Tunneling Junctions, Felice C. Simeone, Hyo Jae Yoon, Martin M. Thuo, Jabulani R. Barber, Barbara Smith, George M. Whitesides Nov 2013

Defining The Value Of Injection Current And Effective Electrical Contact Area For Egain-Based Molecular Tunneling Junctions, Felice C. Simeone, Hyo Jae Yoon, Martin M. Thuo, Jabulani R. Barber, Barbara Smith, George M. Whitesides

Martin M. Thuo

Analysis of rates of tunneling across self-assembled monolayers (SAMs) of n-alkanethiolates SCn (with n = number of carbon atoms) incorporated in junctions having structure AgTS-SAM//Ga2O3/EGaIn leads to a value for the injection tunnel current density J0 (i.e., the current flowing through an ideal junction with n = 0) of 103.6±0.3 A·cm–2 (V = +0.5 V). This estimation of J0 does not involve an extrapolation in length, because it was possible to measure current densities across SAMs over the range of lengths n = 1–18. This value of J0 is estimated under the assumption that values of the geometrical contact area …


A Microfluidic Paper-Based Electrochemical Biosensor Array For Multiplexed Detection Of Metabolic Biomarkers, Chen Zhao, Martin M. Thuo, Xinyu Liu Oct 2013

A Microfluidic Paper-Based Electrochemical Biosensor Array For Multiplexed Detection Of Metabolic Biomarkers, Chen Zhao, Martin M. Thuo, Xinyu Liu

Martin M. Thuo

Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat) for signal readout. The biosensor array can detect several analytes in a sample solution and produce multiple measurements for each analyte from a single run. Using the device, we demonstrate simultaneous detection of glucose, lactate and uric acid in urine, with analytical performance comparable to …


Paramagnetic Ionic Liquids For Measurements Of Density Using Magnetic Levitation, David K. Bwambok, Martin M. Thuo, Manza B.J. Atkinson, Katherine A. Mirica, Nathan D. Shapiro, George M. Whitesides Aug 2013

Paramagnetic Ionic Liquids For Measurements Of Density Using Magnetic Levitation, David K. Bwambok, Martin M. Thuo, Manza B.J. Atkinson, Katherine A. Mirica, Nathan D. Shapiro, George M. Whitesides

Martin M. Thuo

Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic object can be determined by measuring its position in the magnetic field along the vertical axis (levitation height, h), either as an absolute value or relative to internal standards of known density. For density measurements by MagLev, PILs have three advantages over solutions of paramagnetic salts in aqueous …