Apparatus and process for improved measurements of a monitoring device
Methods and devices for improving measurements of test meter, and in particular for detecting a presence of an electrochemical sensor or strip in the test meter and a start time of an electrochemical reaction, are provided. In one exemplary embodiment of an electrochemical system includes an electrochemical sensor , a test meter, and a circuit. The circuit is configured to form an electrical connection with the electrochemical sensor such that the circuit can detect three distinct voltage ranges. The voltage ranges can be indicative of an absence of the electrochemical sensor, a presence of the sensor that is devoid of a sample, and a presence of the sensor with a sample. Test meters, methods for detecting when a sample starts to fill an electrochemical sensor for establishing when a reaction starts, and circuits for use with electrochemical strips, are also provided.
1. An electrochemical system, comprising:
an electrochemical sensor having an electrode;
a test meter configured to receive the electrochemical sensor; and
a high impedance circuit within the test meter, the high impedance circuit including a common electrical connector configured to form an electrical connection with the electrode of the electrochemical sensor when the sensor is disposed in the test meter, the circuit further being configured to detect a first voltage of the common electrical connector indicating that no electrochemical sensor is disposed in the test meter, a second voltage of the common electrical connector, distinct from the first voltage, indicating that the electrochemical sensor that is devoid of a bodily fluid sample is disposed in the test meter, and a third voltage of the common electrical connector, distinct from the first and second voltages, indicating that the electrochemical sensor is disposed in the test meter and a bodily fluid sample has been applied to the electrochemical sensor and wherein the test meter further comprises a sensor port connector including first and second electrical connectors, the circuit being configured such that the presence of an electrochemical sensor in the test meter results in a low impedance connection between the first and second electrical connectors.
2. The electrochemical system of claim 1 , wherein an absolute value of the second voltage is less than an absolute value of the first voltage and an absolute value of the third voltage is less than the absolute value of the second voltage.
3. The electrochemical system of claim 1 , wherein the sensor port connector is further configured such that the presence of a sample in an electrochemical sensor in the test meter results in an electrical connection between the common electrical connector and at least one of the first and second electrical connectors.
4. The electrochemical system of claim 3 , wherein the amount of a sample that is present in the electrochemical sensor is a minimum volume of sample to form an electrical connection between the common electrical connector and at least one of the first and second electrical connectors.
5. The electrochemical system of claim 3 , wherein the high impedance circuit further comprises:
a sense resistor in electrical communication with the second electrical connector;
a detection component electrically connected to the sense resistor and the second electrical connector, the detection component being configured to determine the presence of an electrochemical sensor in the test meter and the presence of a sample in an electrochemical sensor in the test meter;
a voltage reference point electrically connected to the common electrical connector; and
a wetting supply electrically connected to the first electrical connector, the wetting supply being configured to supply a voltage and electrochemically connected to the common electrical connector as a result of the presence of the amount of the sample in the sensor in the test meter.
6. The electrochemical system of claim 5 , further comprising a waveform generator electrically connected to the wetting supply and said other of the first and second electrical connectors, the waveform generator being configured to apply voltage to react the sample disposed in the electrochemical sensor.
7. The electrochemical system of claim 6 , wherein the detection component further comprises an effectively low gain amplifier configured to reduce an effect of current leakage caused by a voltage measurement component in electrical communication with the circuit.
8. The electrochemical system of claim 5 , wherein the voltage reference point further comprises a transimpedance amplifier.
9. The electrochemical system of claim 5 , wherein a resistance ratio between the wetting supply and the sense resistor is approximately 3:2.
10. A method for detecting when a sample starts to fill an electrochemical sensor having an electrode, the method comprising:
providing a test meter having a high impedance circuit, said high impedance circuit comprising:
a detection component;
a sense resistor in electrical communication with the detection component;
a voltage reference point configured to be in electrical connection with an electrode of an electrochemical test strip in contact with the at least one electrical connector; and
a wetting supply configured for supplying a voltage;
measuring, with the test meter, a first voltage of the electrode indicative of absence of the electrochemical sensor;
introducing the electrochemical sensor to the test meter;
measuring, with the test meter, a dry strip voltage of the electrode, the dry strip voltage being distinct from the first voltage, and being indicative of the presence of the electrochemical sensor that is devoid of a sample;
introducing a sample into the electrochemical sensor;
measuring, with the test meter, a wet strip voltage of the electrode, the wet strip voltage being distinct from the dry strip voltage and from the first voltage, and being indicative of the presence of an amount in the sample in the electrochemical sensor disposed in the meter; and
determining when the sample starts to fill the electrochemical sensor based on the measurement of the wet strip voltage.
11. The method of claim 10 , further comprising:
measuring a base voltage prior to introducing an electrochemical sensor to the test meter, the base voltage being indicative of a test meter devoid of an electrochemical sensor, wherein an absolute value of the base voltage is distinct from an absolute value of the dry strip voltage and an absolute value of the wet strip voltage, the absolute value of the wet strip voltage is less than the absolute value of the dry strip voltage, and the absolute value of the dry strip voltage is less than the absolute value of the base voltage.
12. The method of claim 10 , further comprising initiating an electrochemical test upon determining when the sample starts to fill the electrochemical sensor.
13. The method of claim 12 , further comprising operating an effectively low gain amplifier to reduce an effect of current leakage caused by a voltage measurement component in electrical communication with the circuit.