Micro-Well Chemical Sensor Circuits for Low-Noise Impedance Detection
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Solution Overview
Problem
Large-scale sensor arrays face challenges in accurately detecting chemical and biological processes due to susceptibility to noise, which affects the accuracy of signal processing and is exacerbated by the rapid decay or reaction of byproducts.
Innovation Solution
The implementation of chemical sensors using AC excitation and synchronous detection techniques, combined with current/voltage converter circuits and narrowband filtering, to reduce noise and enhance signal discrimination, allowing for the measurement of complex impedance and resistance changes in micro-wells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large-scale sensor arrays are used to monitor chemical reactions, then the detection capability and coverage are improved, but the susceptibility to noise and signal processing accuracy deteriorate
Solution Approach 1:
The patent applies AC excitation with specific frequencies (e.g., 1 kHz, 10 kHz, 100 kHz) to the sensor electrodes, creating periodic electrical signals that interact with ionic species in the reaction medium. This periodic action enables frequency-based signal discrimination, where the sensor response at the excitation frequency can be distinguished from noise at other frequencies, thereby maintaining measurement precision in large-scale arrays
Solution Approach 2:
The patent introduces synchronous detection as an intermediary signal processing technique between the sensor output and the final measurement. This intermediary process correlates the sensor signal with a reference signal at the excitation frequency, effectively filtering out uncorrelated noise while preserving the desired signal, thus resolving the contradiction between array scale and signal accuracy
2Adaptability or versatility
If sensor arrays detect chemical byproducts, then the monitoring comprehensiveness is improved, but the detection accuracy deteriorates due to rapid decay or reaction of byproducts
Solution Approach 1:
The patent applies AC excitation continuously to maintain ionic species in an active state before they can decay or react. By establishing the excitation field in advance, the sensor captures signals from ionic species at the moment of their presence in the reaction, enabling comprehensive monitoring without losing accuracy due to byproduct decay
Solution Approach 2:
The periodic AC excitation creates repeated measurement cycles that capture transient ionic species multiple times during their brief existence. This periodic sampling increases the probability of detecting decaying byproducts while maintaining measurement precision through frequency-specific signal extraction
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 significantly reduces noise, achieving an SNR of approximately 10 and enabling accurate detection of 1% impedance variations, thereby improving the accuracy of chemical and biological process analysis.
Implementation Method 1
A change in dielectric or electrical property of the sensor may be measured, for example, by one or more of a change in electrical impedance, capacitance, inductance, conductance or resistance
Implementation Method 2
A change in dielectric or electrical property of the sensor may be measured, for example, by one or more of a change in electrical impedance
Implementation Method 3
The implementation of chemical sensors using AC excitation and synchronous detection techniques, combined with current/voltage converter circuits and narrowband filtering, to reduce noise and enhance signal discrimination
Data Source
AI summary
A chemical sensor for analyte solutions utilizes AC excitation of a sample distributed in one or more micro-wells of a measurement device. The sensors utilize narrowband filtering of the measured signal(s), resulting in a large reduction in noise. Synchronous detection is utilized to provide high discrimination of the desired signal from noise or interfering sources. Conductance and by extension impedance is measured by applying a constant alternating current (AC) voltage across the electrodes of each micro-well and measuring the resulting current.