title: Attofarad resolution potentiostat for electrochemical measurements on nanoscale biomolecular interfacial systems.
abstract: We present an instrument that enables electrochemical measurements (cyclic voltammetry, impedance tracking, and impedance spectroscopy) on submicrometric samples. The system features a frequency range from dc to 1 MHz and a current resolution of 10 fA for a measurement time of 1 s, giving a sensitivity of few attofarads in terms of measurable capacitance with an applied voltage of only 100 mV. These performances are obtained using a low-noise wide-bandwidth integrator/differentiator stage to sense the input current and a modular approach to minimize the effect of input stray capacitances. A digitally implemented lock-in filter optimally extracts the impedance of the sample, providing time tracking and spectroscopy operating modes. This computer-based and flexible instrument is well suited for characterizing and tracking the electrical properties of biomolecules kept in the physiological solution down to the nanoscale.
authors.affiliation: Dipartimento di Elettronica e Informazione, Unità IIT Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Carminati
authors.forename: Giorgio
authors.initials: G
authors.lastname: Ferrari
authors.forename: Marco
authors.initials: M
authors.lastname: Sampietro
mesh_terms: D000465:Algorithms; D000669:Amplifiers, Electronic; D003201:Computers; D004058:Diffusion; D025802:Electric Capacitance; D017097:Electric Impedance; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004573:Electrolytes / Q000737:chemistry; D004867:Equipment Design; D008839:Microelectrodes; D036103:Nanotechnology / Q000295:instrumentation*; D012984:Software; D013057:Spectrum Analysis / Q000295:instrumentation; D013997:Time Factors
chemical_list: D004573:Electrolytes