Electrochemical Cell Impedance Measurement via Chirp Deconvolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrochemical impedance measurements in sensors are limited by low signal-to-noise ratio (SNR) due to the inherent non-linearity of electrochemical cells, which is exacerbated by the need for battery-powered devices to minimize power consumption.
Innovation Solution
The use of a chirp signal to separate linear and non-linear components of the output signal through deconvolution, allowing for increased stimulus amplitude without increasing power consumption, by employing drive circuitry to apply a stimulus and measurement circuitry to measure and separate the output signal into linear and non-linear components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amplitude of stimulus is increased to improve signal-to-noise ratio, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The output signal is segmented into linear and non-linear components through deconvolution with the chirp stimulus. This allows the system to extract the linear impedance response (which contains the measurement information) while rejecting non-linear artifacts, thereby improving measurement precision without requiring increased stimulus amplitude and power consumption.
Solution Approach 2:
The patent changes the temporal characteristics of the stimulus from a traditional sinusoidal wave to a chirp signal with time-varying frequency. This parameter change enables the stimulus to excite a broader frequency spectrum, improving the signal-to-noise ratio for impedance measurements without increasing the amplitude and thus without increasing power consumption.
2Measurement precision
If acquisition time is extended to improve signal-to-noise ratio, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The chirp stimulus is applied as a periodic signal with specific frequency modulation characteristics. This periodic action allows the system to achieve frequency spectrum coverage equivalent to extended acquisition times, but within a shorter measurement window, thereby improving both signal-to-noise ratio and measurement speed.
Solution Approach 2:
The chirp stimulus pre-excites the electrochemical cell across a broad frequency spectrum before the measurement is completed. This preliminary excitation ensures that all frequency components of interest are already activated, allowing rapid acquisition of impedance data without requiring extended measurement times.
3Volume of moving object
If device size is reduced for battery-powered applications, then portability is improved, but measurement precision deteriorates
Solution Approach 1:
By changing the stimulus from a single-frequency sinusoid to a time-varying chirp signal, the system achieves broader frequency excitation with the same hardware amplitude limits. This parameter change improves signal-to-noise ratio without requiring larger devices, enabling portable battery-powered operation with maintained measurement precision.
Data Source
AI summary
Circuitry for determining an impedance of an electrochemical cell comprising at least one first electrode and a second electrode, the circuitry comprising: drive circuitry configured to apply a stimulus to the electrochemical cell, the stimulus having a stimulation frequency and a stimulation amplitude; and measurement circuitry configured to: measure an output of the electrochemical cell to generate an output signal; separate the output signal into a linear component and a non-linear component; and determine the impedance of the cell based on the linear component of the response.