摘要 |
An electrochemical system for determining the concentration of an analyte in a solution has a first electrode 6 for immersion in the solution 10 and transducer means 12 for oscillating the solution in a vertical direction relative to the first electrode 6. A bias voltage is applied between the first electrode 6 and a second electrode 13 which is also immersed in the solution. Phase sensitive detection means is provided and comprises a current to voltage converter coupled in series with the first and second electrodes. The output voltage provided by the converter is coupled to an input of a lock-in amplifier which also receives an input signal corresponding to an oscillating signal used to drive the transducer means 12. The lock-in amplifier provides an output signal which is proportional to the faradaic component flowing through that portion of the first electrode which is oscillating into and out of the solution. |