Open Circuit Delay Devices for Analyte Measurement
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Solution Overview
Problem
Conventional test meters using switches in the conductive path between electrodes and transimpedance amplifiers can experience uncompensated voltage drops during open circuit conditions, leading to inaccurate analyte measurements due to galvanic potentials and leakage currents, which corrupt the open circuit and affect measurement accuracy.
Innovation Solution
The implementation of a circuit with an operational amplifier and a shutdown control circuit, or a switch configuration that connects and disconnects the output to prevent uncompensated voltage drops, ensuring accurate test current measurement by maintaining a true open circuit and minimizing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch is used in the conductive path between electrodes and transimpedance amplifiers to create open circuit conditions, then the open circuit can be established, but uncompensated voltage drops occur leading to measurement inaccuracies
Solution Approach 1:
The patent removes the switch from the conductive path between the electrodes and transimpedance amplifier. Instead, the switch is placed in a different location that allows open circuit conditions to be established without interrupting the feedback path. This extraction of the switch from the critical measurement path eliminates the source of uncompensated voltage drops while preserving the ability to create open circuit conditions for analyte measurement.
2Measurement precision
If a switch is placed in the feedback path of the transimpedance amplifier, then uncompensated voltage drops are prevented, but the circuit complexity increases
Solution Approach 1:
The patent designs the switch to serve multiple functions: it establishes open circuit conditions for analyte measurement, maintains the feedback path integrity to prevent uncompensated voltage drops, and controls the operational amplifier's shutdown mode. By making the switch multi-functional, the patent avoids adding extra components that would increase circuit complexity, as the same switch handles multiple critical tasks in the measurement system.
3Reliability
If the operational amplifier remains active during open circuit conditions, then continuous monitoring is possible, but leakage currents corrupt the open circuit and reduce measurement accuracy
Solution Approach 1:
The patent implements periodic control of the operational amplifier's activity state. The operational amplifier is activated during measurement phases to monitor analyte concentrations and deactivated (shutdown mode) during open circuit conditions to eliminate leakage currents. This periodic on-off operation allows the system to alternate between continuous monitoring capability and high-precision open circuit measurement, with the switch coordinating these state transitions.
Data Source
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AI summary
System, circuits, and methods to reduce or eliminate uncompensated voltage drop between an electrode of an electrochemical cell usable for analyte measurement. In one example, a system is provided that includes a test strip, a reference voltage circuit, an operational amplifier connected to the reference voltage circuit to provide a pre-determined fraction of a reference voltage substantially equal to the test voltage applied to the first line, the operational amplifier having an output configured for one of a connected or disconnected state to the first line, and a processing circuit connected to the output of the operational amplifier and the first line such that, during a disconnected state between the output and the first line, the processing circuit remains in connection with the first line. In another example, a method of measuring an electrochemical reaction of an electrochemical cell is provided that includes applying a test voltage to the first electrode and connecting the second electrode to ground; uncoupling the first electrode from the output of the circuit while allowing electrical communication from the first electrode to the processor; and coupling the first electrode to the output to measure a test current generated in the electrochemical cell without an uncompensated voltage drop.