Virtual instruments are computer programs that interact with real world objects by means of sensors and actuators and implement functions of real or imaginary instruments. The sensor is usually a simple hardware that acquires data from the object, transforms it into electric signals and transmits to the computer for further processing. Simple virtual measuring instruments just acquire and analyse data, but more complex virtual instruments communicate with objects in both directions. The outgoing signals execute probing and control by actuators.
Real world signals are of analogue nature, while a computer is a digital instrument; therefore the computer needs also interpreters – analogue-to-digital and digital-to-analogue converters for communication with the object under investigation. ADC and DAC boards that implement this function in inexpensive systems are usually placed inside the computer. Compact external ADC/DAC converters with USB interface are also becoming popular.
Both the input and output signals in electrochemistry are of electric origin, so the sensors and actuators in principle may be omitted. However, a potentiostat is a common instrument available in every electrochemical laboratory and there is no absolute necessity to simulate its functions. We use a potentiostat as the only hardware component of the virtual impedance spectrometer, besides a computer with its ADC/DAC interface. The potentiostat also adjusts power consumption in the electrochemical experiment (the power of a common DAC board is sufficient to control electrochemical reaction just on microelectrode). While the virtual spectrometer controls the electrode potential by a potentiostat with low load on the CPU, the major part of the computer resources is consumed to implement probing, data acquisition, signal processing and visualisation of impedance spectra variation immediately in the potential scan in the real-time mode.
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Physico-Chemical Research Institute Belarusian State University  |
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