Abstract: In an improved amperometric gas sensor, the structure, composition, and electrode potential are adjusted so as to prevent or minimize any unwanted reactivity at the counter and/or reference electrode of any analyte or interfering component of the matrix that may cross over thereto. The sensor is preferably structured so that the product of the analyte reaction at a first working electrode can be reconverted to the original analyte at a counter electrode or at a second working electrode and then reacted again at the first working electrode, with such back-and-forth reactions repeating many times, so as to yield an amplification of the analyte signal.

Abstract: In an improved amperometric gas sensor, the structure, composition, and electrode potential are adjusted so as to prevent or minimize any unwanted reactivity at the counter and/or reference electrode of any analyte or interfering component of the matrix that may cross over thereto. The sensor is preferably structured so that the product of the analyte reaction at a first working electrode can be reconverted to the original analyte at a counter electrode or at a second working electrode and then reacted again at the first working electrode, with such back-and-forth reactions repeating many times, so as to yield an amplification of the analyte signal.

Abstract: A unique imaging sensor consists of a two-dimensional array of impedance electrode elements separated from chemical or biological samples contained in or containing fluids by a fluid-impervious layer which prevents electrode fouling. It can serve for various chemical and biological sensing applications, ranging from diagnosing cancer to monitoring metabolic changes in real time or the progress of cryosurgery. The imaging can be applied to single cells in a manner that allows only specific cell lines to attach [using selective derivatization of the layer surface], then monitors their viability, type, and status with impedance, and further measures their size and shape by use the two-dimensionality of the electrodes array.