Single-Choice Kapitel 1

Thermal transducers react on the variation of electro-magnetic radiation, whereas optical transducers are based on calorimetric effects.

Potentiometry belongs to the techniques without current flow.

Amperometry, coulometry and voltammetry require full analyte conversion.

Negligble analyte conversion can be found in field-effect sensors.

In potentiometry Nikolsky equation can be “simplified” as Nernst equation for a low selectivity coefficient.

In potentiometry Nikolsky equation can be “simplified” as Nernst equation for a high selectivity coefficient.

In potentiometry the charge transfer resistance must be as high as possible for pH glass electrodes.

In potentiometry the electrochemical double layer exists up to around a few μm distant from the electrode surface.

In potentiometry the three-electrode setup consits of a working electrode (ISE), counter electrode and a reference electrode.

In potentiometry a combination glass electrode houses two silver/silver chloride internal reference elements.

In potentiometry the diaphragm potential should be as small as possible.

In amperometry the ion concentration linearly depends on the diffusion-limiting current.

In amperometry the ion concentration logarithmically depends on the diffusion-limiting current.

In amperometry the concentration of redox-active species linearly depends on the diffusion-limiting current.

In amperometry the concentration of redox-active species logarithmically depends on the diffusion-limiting current.

In amperometry a defined voltage step is applied to determine the Faradaic current induced by the electrochemical conversion of the analyte.

In amperometry the electrode size has influence on the overall sensor signal, macreoelectrodes deliver higher currents.

In amperometry solutions are often stirred in comparison to voltammetry, where quiescent solutions are preferred.

In amperometry the reference electrode should be polarizable to guarantee a stable potential of the two-electrode setup.

In sensor signals drift is the ability of the sensor to discriminate one measured variable in the presence of others.

In sensor signals drift means the output of the sensor signal when a zero measurement value is applied.

In sensor signals hysteresis is the maximum difference in the output signal within the measurement range when the value is approached in increasing / decreasing order.

In sensor signals the upper detection limit is the lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value) within a stated confidence level.

In sensor signals operating time is the maximum length of sensor operation without changing its performance beyond defined tolerances.

Typical blood glucose concentrations are in the micromolar level.

For cyclic voltammetry, typically a triangular waveform is applied with start and end potential.

For cyclic voltammetry, typically a rectangular waveform is applied with start and end potential.

Amperometric measurements have to consider both the Faradaic and charging current; the latter is due to unwanted physical side-effects.

The charging current in amperometry leads to the formation of an electrical double layer.

Glucose biosensing by glucose oxidase either consumes H2O2 as electron acceptor or produces O2.

For potentiometric sensors, the sensor signal is temperature-dependent.

Potentiometric biosensors have a typical S-shaped calibration curve (see alkaline / acidic error; pH glass electrode) in contrast to amperometric biosensors.