Electrochemical sensor with zero calibration feature and method of calibrating

摘要

An easily calibrated analytical instrument for sensing a target analyte. The instrument includes an electrochemical sensor and a switch. The electrochemical sensor includes a sensing electrode and a counter electrode. The switch is a normally open switch effective for creating a short circuit between the sensing and counter electrodes when closed. A zero calibration reading can be taken when the switch is closed.

主权项

1. An analytical instrument, comprising:
(a) an electrochemical sensor for sensing a target analyte in a test volume, the electrochemical sensor comprising a single sensing electrode and a single counter electrode, both in contact with a common electrolyte and a common test volume, for generating an electrical current proportional to the concentration of target analyte present in the test volume, (b) a signaling module in electrical communication with the electrochemical sensor for receiving electrical current generated by the electrodes and producing an electrical output signal proportional to the electrical current, (c) a normally open switch for providing an electrical short circuit between the single sensing and single counter electrodes when closed, whereby electrical current generated by the electrodes bypasses the signaling module when the switch is closed, and (d) a microprocessor containing a span calibration value and a zero calibration value in memory, the microprocessor in electrical communication with the signaling module and the switch wherein:
(1) when the switch is open the microprocessor receives an electrical analysis signal comprised of the electrical output signal and any background signal, and either:
(A) calibrates the electrical analysis signal employing a calibration value derived from the span calibration value and the zero calibration value in memory, and correlates the calibrated electrical analysis signal to a numerical value indicating the concentration of analyte in the test volume, or(B) correlates the electrical analysis signal to a numerical value indicating the concentration of analyte in the test volume, and calibrates the numerical value of concentration employing a calibration value derived from the span calibration value and the zero calibration value in memory, and(2) when the switch is closed no electrical signal from any electrode reaches the signaling module whereby the microprocessor receives only background signal and either (A) replaces the zero calibration value in memory with the value of the received background signal, or (B) correlates the received background signal to a numerical value indicating a concentration of analyte and replaces the zero calibration value in memory with the numerical value of concentration.