Capacitance Detection in Biosensor Test Cell Using Phase Angle Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrochemical analyte detection methods in biosensors are prone to inefficiencies and errors due to temperature variations and partial filling of test strips, which affect capacitance measurements and lead to inaccurate results.
Innovation Solution
A method that calculates capacitance in biosensor test strips by applying an oscillating signal, determining a phase angle, and using a microcontroller to adjust sampling intervals, allowing for accurate capacitance measurement without requiring resistance determination, using the equation C=|iT sin(Φ+ΦCOMP)|/2πfV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance measurement is performed using conventional sampling methods, then measurement speed is maintained, but measurement accuracy deteriorates due to parallel strip resistance effects and phase shifts
Solution Approach 1:
The patent applies preliminary action by performing resistance measurement and phase shift compensation before the capacitance measurement. The system pre-determines the parallel strip resistance value and uses it to compensate for phase shifts in the capacitance measurement circuit, thereby eliminating measurement errors before they occur.
Solution Approach 2:
The patent introduces an intermediary approach by using a known resistance value as a reference to compensate for the unknown parallel strip resistance effects. The system measures or estimates the resistance component separately and uses it as an intermediary parameter to correct the capacitance measurement, isolating the capacitance determination from resistance interference.
2Measurement precision
If conventional capacitance measurement is used, then device complexity is low, but measurement accuracy deteriorates due to temperature variations and partial filling effects
Solution Approach 1:
The patent applies universality by designing a measurement system that can perform both resistance measurement and capacitance measurement using the same hardware circuitry. The single measurement system is configured to alternatively measure different electrical parameters, eliminating the need for separate dedicated circuits for each measurement type.
Solution Approach 2:
The patent utilizes parameter changes by switching between different measurement modes (resistance mode and capacitance mode) using the same hardware. The system changes the electrical parameters being measured by reconfiguring the measurement circuit timing and signal application, rather than using physically different measurement paths.
3Measurement precision
If sampling is performed at standard intervals, then processing speed is maintained, but measurement accuracy deteriorates due to phase shift uncertainties
Solution Approach 1:
The patent applies periodic action by using synchronized sampling that occurs at specific phases of the excitation signal cycle. The measurement system samples the response signal at predetermined time intervals that are synchronized with the periodic excitation signal, ensuring consistent phase relationship measurements.
Solution Approach 2:
The patent replaces mechanical timing adjustments with electronic phase shift compensation. Instead of physically adjusting sampling timing to account for phase shifts, the system uses electronic calculation to determine and compensate for phase differences based on measured signal characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the accuracy and reliability of analyte measurements by accounting for phase shifts and parasitic resistance, reducing errors caused by temperature and partial filling, and providing more precise capacitance calculations.
Implementation Method 1
calculating a capacitance of the chamber from the phase angle
Implementation Method 2
determining a phase angle between an output signal and the oscillating input signal
Data Source
AI summary
A method and a system are provided to determine fill sufficiency of an electrochemical biosensor test cell by determining capacitance of the electrochemical test cell. In particular, the system samples an output signal from the chamber at a second sampling-time interval different than a first sampling-time interval such that a magnitude of each sampled output signal is measured at each succession of the second sampling-time interval instead of at the first time interval. The system determines a phase angle between an output signal and the oscillating input signal from the chamber based on the sampled output signal of the sampling step. The system calculates a capacitance of the chamber from the phase angle. A method is also provided to perform similar functionalities of the system.