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DStat: A Versatile, Open-Source Potentiostat for Electroanalysis and Integration.

Dryden MD, Wheeler AR - PLoS ONE (2015)

Bottom Line: Likewise, in head-to-head tests, DStat's potentiometric precision is similar to that of a commercial pH meter.Most importantly, the versatility of DStat was demonstrated through integration with the open-source DropBot digital microfluidics platform.In sum, we propose that DStat is a valuable contribution to the "open source" movement in analytical science, which is allowing users to adapt their tools to their experiments rather than alter their experiments to be compatible with their tools.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Toronto, Toronto, ON, Canada.

ABSTRACT
Most electroanalytical techniques require the precise control of the potentials in an electrochemical cell using a potentiostat. Commercial potentiostats function as "black boxes," giving limited information about their circuitry and behaviour which can make development of new measurement techniques and integration with other instruments challenging. Recently, a number of lab-built potentiostats have emerged with various design goals including low manufacturing cost and field-portability, but notably lacking is an accessible potentiostat designed for general lab use, focusing on measurement quality combined with ease of use and versatility. To fill this gap, we introduce DStat (http://microfluidics.utoronto.ca/dstat), an open-source, general-purpose potentiostat for use alone or integrated with other instruments. DStat offers picoampere current measurement capabilities, a compact USB-powered design, and user-friendly cross-platform software. DStat is easy and inexpensive to build, may be modified freely, and achieves good performance at low current levels not accessible to other lab-built instruments. In head-to-head tests, DStat's voltammetric measurements are much more sensitive than those of "CheapStat" (a popular open-source potentiostat described previously), and are comparable to those of a compact commercial "black box" potentiostat. Likewise, in head-to-head tests, DStat's potentiometric precision is similar to that of a commercial pH meter. Most importantly, the versatility of DStat was demonstrated through integration with the open-source DropBot digital microfluidics platform. In sum, we propose that DStat is a valuable contribution to the "open source" movement in analytical science, which is allowing users to adapt their tools to their experiments rather than alter their experiments to be compatible with their tools.

No MeSH data available.


Related in: MedlinePlus

Cell current conversion to voltage for ADC.(a) Current measurement by shunt resistor. The measurement resistor RM causes a voltage drop proportional to the cell current i by Ohm’s Law. The voltage drop is measured across the resistor but the counter electrode voltage VCE (present on both sides of the resistor) complicates measurement. (b) Current measurement using a transimpedance amplifier. The measurement resistor RM is placed in a negative feedback loop of an op amp (U3) whose inverting input is connected to the working electrode. U3’s non-inverting input is tied to ground, producing a virtual ground at the inverting input. When current i flows through the working electrode, it induces a voltage drop VR across RM, which is balanced by U3 output VO to maintain the virtual ground at its inverting input.
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pone.0140349.g003: Cell current conversion to voltage for ADC.(a) Current measurement by shunt resistor. The measurement resistor RM causes a voltage drop proportional to the cell current i by Ohm’s Law. The voltage drop is measured across the resistor but the counter electrode voltage VCE (present on both sides of the resistor) complicates measurement. (b) Current measurement using a transimpedance amplifier. The measurement resistor RM is placed in a negative feedback loop of an op amp (U3) whose inverting input is connected to the working electrode. U3’s non-inverting input is tied to ground, producing a virtual ground at the inverting input. When current i flows through the working electrode, it induces a voltage drop VR across RM, which is balanced by U3 output VO to maintain the virtual ground at its inverting input.

Mentions: The potentiostatic circuit and control signal are sufficient to maintain a desired working electrode potential, but for almost all experiments involving a potentiostat, measurement of the current passing through the working electrode is required. Because the majority of analogue to digital converters (ADC) cannot measure a current directly, the current must first be converted to voltage to obtain a digital signal suitable for recording by a computer. The simplest technique to accomplish this (used in some of the home-made potentiostats described in the literature [14, 17]) is the current shunt, shown in Fig 3(a), where the voltage drop is measured across a measurement resistor RM placed in series between the counter electrode and the control amplifier output. In practice, because ADCs cannot measure an infinitely large range of voltages, it is necessary to switch between different RMs to cover the several orders of magnitude of currents of interest in electrochemical experiments.


DStat: A Versatile, Open-Source Potentiostat for Electroanalysis and Integration.

Dryden MD, Wheeler AR - PLoS ONE (2015)

Cell current conversion to voltage for ADC.(a) Current measurement by shunt resistor. The measurement resistor RM causes a voltage drop proportional to the cell current i by Ohm’s Law. The voltage drop is measured across the resistor but the counter electrode voltage VCE (present on both sides of the resistor) complicates measurement. (b) Current measurement using a transimpedance amplifier. The measurement resistor RM is placed in a negative feedback loop of an op amp (U3) whose inverting input is connected to the working electrode. U3’s non-inverting input is tied to ground, producing a virtual ground at the inverting input. When current i flows through the working electrode, it induces a voltage drop VR across RM, which is balanced by U3 output VO to maintain the virtual ground at its inverting input.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4624907&req=5

pone.0140349.g003: Cell current conversion to voltage for ADC.(a) Current measurement by shunt resistor. The measurement resistor RM causes a voltage drop proportional to the cell current i by Ohm’s Law. The voltage drop is measured across the resistor but the counter electrode voltage VCE (present on both sides of the resistor) complicates measurement. (b) Current measurement using a transimpedance amplifier. The measurement resistor RM is placed in a negative feedback loop of an op amp (U3) whose inverting input is connected to the working electrode. U3’s non-inverting input is tied to ground, producing a virtual ground at the inverting input. When current i flows through the working electrode, it induces a voltage drop VR across RM, which is balanced by U3 output VO to maintain the virtual ground at its inverting input.
Mentions: The potentiostatic circuit and control signal are sufficient to maintain a desired working electrode potential, but for almost all experiments involving a potentiostat, measurement of the current passing through the working electrode is required. Because the majority of analogue to digital converters (ADC) cannot measure a current directly, the current must first be converted to voltage to obtain a digital signal suitable for recording by a computer. The simplest technique to accomplish this (used in some of the home-made potentiostats described in the literature [14, 17]) is the current shunt, shown in Fig 3(a), where the voltage drop is measured across a measurement resistor RM placed in series between the counter electrode and the control amplifier output. In practice, because ADCs cannot measure an infinitely large range of voltages, it is necessary to switch between different RMs to cover the several orders of magnitude of currents of interest in electrochemical experiments.

Bottom Line: Likewise, in head-to-head tests, DStat's potentiometric precision is similar to that of a commercial pH meter.Most importantly, the versatility of DStat was demonstrated through integration with the open-source DropBot digital microfluidics platform.In sum, we propose that DStat is a valuable contribution to the "open source" movement in analytical science, which is allowing users to adapt their tools to their experiments rather than alter their experiments to be compatible with their tools.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Toronto, Toronto, ON, Canada.

ABSTRACT
Most electroanalytical techniques require the precise control of the potentials in an electrochemical cell using a potentiostat. Commercial potentiostats function as "black boxes," giving limited information about their circuitry and behaviour which can make development of new measurement techniques and integration with other instruments challenging. Recently, a number of lab-built potentiostats have emerged with various design goals including low manufacturing cost and field-portability, but notably lacking is an accessible potentiostat designed for general lab use, focusing on measurement quality combined with ease of use and versatility. To fill this gap, we introduce DStat (http://microfluidics.utoronto.ca/dstat), an open-source, general-purpose potentiostat for use alone or integrated with other instruments. DStat offers picoampere current measurement capabilities, a compact USB-powered design, and user-friendly cross-platform software. DStat is easy and inexpensive to build, may be modified freely, and achieves good performance at low current levels not accessible to other lab-built instruments. In head-to-head tests, DStat's voltammetric measurements are much more sensitive than those of "CheapStat" (a popular open-source potentiostat described previously), and are comparable to those of a compact commercial "black box" potentiostat. Likewise, in head-to-head tests, DStat's potentiometric precision is similar to that of a commercial pH meter. Most importantly, the versatility of DStat was demonstrated through integration with the open-source DropBot digital microfluidics platform. In sum, we propose that DStat is a valuable contribution to the "open source" movement in analytical science, which is allowing users to adapt their tools to their experiments rather than alter their experiments to be compatible with their tools.

No MeSH data available.


Related in: MedlinePlus