Current-to-Frequency Converter for Baseline Sensor Current Subtraction
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Solution Overview
Problem
Conventional electrochemical sensors face challenges in subtracting baseline output signals from measured signals in power and space-constrained environments, such as contact lenses, due to the need for separate readout circuits for primary and reference sensors.
Innovation Solution
A linear relaxation oscillator-based current-to-frequency converter circuit is used to subtract output current primary signals from reference signals in the current domain, producing a frequency output signal indicative of the difference between the two, eliminating the need for separate readout circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate readout circuits are employed for primary and reference electrochemical sensors to subtract baseline signals, then signal processing accuracy is improved, but device complexity and physical space requirements increase
Solution Approach 1:
The patent combines the readout functions of both primary and reference sensors into a single shared readout circuit. The circuit alternates between measuring the primary sensor signal and the reference sensor signal, performing baseline subtraction through sequential measurement and digital processing rather than requiring separate simultaneous readout circuits. This merging approach maintains measurement precision while reducing device complexity and physical space requirements.
Solution Approach 2:
The readout circuit employs periodic switching between measuring the primary sensor and the reference sensor. The circuit alternates between these two measurement modes in a periodic fashion, allowing a single circuit to perform the function of what would traditionally require two separate circuits. This periodic action enables baseline subtraction while using shared hardware resources.
2Measurement precision
If separate readout circuits are employed for primary and reference electrochemical sensors, then signal processing capability is improved, but power consumption increases
Solution Approach 1:
The patent merges the readout functionality into a single power-consuming circuit that serves both sensors. By consolidating the readout operations, the total power consumption is reduced compared to running two separate readout circuits simultaneously. The shared circuit is activated periodically to measure each sensor in turn, optimizing power efficiency.
Solution Approach 2:
The readout circuit uses periodic measurement cycles to alternate between the primary and reference sensors. Instead of continuously powering both readout circuits, the single shared circuit is activated in periodic intervals to measure each sensor sequentially. This periodic operation significantly reduces average power consumption while maintaining the ability to perform baseline subtraction for accurate signal processing.
Data Source
AI summary
This disclosure relates to systems and/or methods for subtracting in the current domain an output current primary signal from a primary sensor from an output current reference signal from a reference sensor to produce a frequency output signal indicative of the difference between the output current primary signal and the output current reference signal.