POTENTIOSTAT CIRCUIT
A potentiostat circuit is described for the detection and analysis of analytes within an uncompartmented or galvanically connected pool of liquid and which permits sequential and simultaneous measurements to be performed in multiple electrochemical cells within the uncompartmented or galvanically connected pool of liquid by one or more potentiostats. Accordingly, the potentiostat circuit includes a grounded counter electrode that is configured to prevent against electrical interference when measuring analytes in a fluid sample. The grounded counter electrode can completely surround a working electrode and a reference electrode and can be held at a common potential voltage during operation. The grounded counter electrode can have a U-shape for surrounding on three sides the working electrode and the reference electrode.
1 . A potentiostat circuit comprising:
an electrochemical cell;
a reference electrode in electrical communication with a first high impedance component;
a working electrode in electrical communication with a second high impedance component; and
a counter electrode in electrical communication with a circuit ground.
2 . The potentiostat circuit as defined in claim 1 , wherein the first high impedance component is a first electrometer comprising:
a first operational amplifier which is configured to receive a reference electrode voltage at a first input terminal and generate a first output voltage based on the reference electrode voltage at a first output terminal.
3 . The potentiostat circuit as defined in claim 2 , wherein the second high impedance component is a second electrometer comprising:
a second operational amplifier which is configured to receive a working electrode voltage at a first input terminal and generate a second output voltage based on the working electrode voltage at a second output terminal.
4 . The potentiostat circuit as defined in claim 3 , the potentiostat circuit further comprising:
a third operational amplifier which includes a positive input terminal that is in electrical communication with the circuit ground and a negative input terminal that is in electrical communication with the first output terminal, and the third operational amplifier is configured to receive the first output voltage at the negative input terminal and generate a third output voltage that is based on the first output voltage.
5 . The potentiostat circuit as defined in claim 4 , the potentiostat circuit further comprising:
a fourth operational amplifier which includes a positive input terminal that is in electrical communication with a circuit ground and a negative input terminal that is in electrical communication with the third output terminal, the second output terminal and a digital to analog converter, and the fourth operational amplifier is configured to generate a fourth output voltage that is the sum of the voltages received at the positive input terminal.
6 . The potentiostat circuit as defined in claim 5 , the potentiostat circuit further comprising:
a measurement resistor in electrical communication with the working electrode; and
a fifth operational amplifier which includes a positive input terminal that is in electrical communication with the second output terminal and a negative input terminal that is in electrical communication with the fourth output terminal and the measurement resistor, and wherein the fifth operational amplifier is configured to generate a fifth output voltage indicative of an electrochemical property of a solution within the electrochemical cell.
7 . The potentiostat circuit as defined in claim 6 , wherein the working electrode is associated with a reagent composition for detecting an analyte in a fluid contacted with the working electrode.
8 . The potentiostat circuit as defined in claim 7 , wherein the counter electrode has a U-like shape that defines an electrode receiving area.
9 . The potentiostat circuit as defined in claim 8 , wherein the common counter electrode comprises an array of interconnected U-shaped sections, each U-shaped section serving as a counter electrode for a corresponding electrochemical cell, each U-shaped section defining a corresponding electrode receiving area.
10 . The potentiostat circuit as defined in claim 9 , wherein one or more of the working electrode includes a reagent composition that is an indicator for pH of a fluid contacting the working electrode.
11 . The potentiostat circuit as defined in claim 9 , wherein the reagent composition is formulated to detect an analyte found in blood.
12 . The potentiostat circuit as defined in claim 9 , wherein the reagent composition is formulated to detect an analyte comprising glucose.
13 . An apparatus for measuring analytes in a fluid comprising;
a reservoir for holding a fluid;
an electrochemical sensor including a support having a first side and a second and opposite side;
at least one electrochemical cell disposed on the first side of the support, the at least one electrochemical cell including a reference electrode having an end that is contiguous with a first side and a second side, a working electrode spaced from the reference electrode that also has an end that is contiguous with a first side and a second side, and a counter electrode, the counter electrode having a shape that defines an electrode receiving area, the electrode receiving area surrounding the first side, the second side, and the end of the reference electrode and the working electrode;
a first high impedance component in electrical communication with the reference electrode;
a second high impedance component in electrical communication with the working electrode;
a circuit ground in electrical communication with the counter electrode; and
an analyzing device that electrically connects to each of the reference electrode, working electrode and counter electrode, the analyzing device being configured to simultaneously measure different analytes loaded into the fluid reservoir.