Biosensor Capillary Diffusion Control for Temperature-Compensated Analyte Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing biosensor systems inaccurately measure analyte concentrations due to temperature discrepancies between the internal device temperature and the blood sample temperature, leading to measurement errors.
Innovation Solution
A biosensor system with a sensor chip featuring a capillary that limits the diffusion distance of electron-transfer mediators and analytes, and a voltage application method where a second voltage is applied before a first voltage to minimize temperature's effect on measurement results, using a reagent layer with a redox enzyme and electron-transfer mediator to measure analyte concentration based on current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the internal temperature of the measurement device is measured with a temperature sensor, then the temperature can be monitored, but the measured temperature does not accurately reflect the temperature of the blood sample, leading to measurement errors
Solution Approach 1:
The patent introduces a mediator substance (ferrocene or ferricenium ion) that transfers electrons between the electrode and the enzyme reaction system. This mediator enables the electrode to detect the enzymatic reaction products indirectly, allowing temperature compensation through voltage application without requiring direct thermal contact between the sensor and blood sample, thus resolving the temperature measurement accuracy issue while maintaining concentration measurement precision
2Measurement precision
If a second voltage is applied to the electrodes prior to the first voltage, then the effect of liquid sample temperature on measurement results is diminished, but the measurement process becomes more complex
Solution Approach 1:
The patent applies a second voltage (open circuit voltage or low voltage) to the electrodes before applying the first voltage (measurement voltage). This preliminary voltage application prepares the mediator system and establishes a baseline that compensates for temperature effects. The sequence is: (1) apply second voltage to equilibrate the system, (2) then apply first voltage for measurement. This preliminary action reduces temperature sensitivity without requiring complex hardware modifications
3Measurement precision
If the capillary height is limited to less than the maximum diffusion distance sum, then temperature-induced diffusion variance is reduced, but the measurement volume is constrained
Solution Approach 1:
The patent changes the capillary height parameter to be less than the maximum value of the sum of diffusion distances of the electron-transfer mediator and the analyte at the upper limit measurement guaranteed temperature. This parameter optimization ensures that diffusion processes complete within the capillary before temperature variations cause significant variance, while the mediator system compensates for the reduced sample volume to maintain measurement sensitivity
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 reduces variance in measurement results caused by temperature fluctuations, providing more accurate analyte concentration measurements across a wide range of temperatures using a single calibration curve.
Implementation Method 1
a capillary into which a liquid sample is introduced, whose height is less than the maximum value of the sum of the diffusion distance of the electron-transfer mediator and the diffusion distance of the analyte
Implementation Method 2
The concentration of the analyte is calculated on the basis of the amount of oxidized product and reduced product produced by an enzyme cycling reaction via a redox enzyme in which the analyte serves as the substrate
Implementation Method 3
a concentration measurement section that measures the concentration of the analyte on the basis of the value of the current flowing through the liquid sample during the first voltage application
Data Source
AI summary
A biosensor system can comprise a sensor chip and a measurement device. The sensor chip comprises a capillary and electrodes disposed within the capillary. The height of the capillary is set to be less than the maximum value of the sum of the diffusion distance of an electron-transfer mediator and the diffusion distance of an analyte at the upper limit of the measurement guaranteed temperature of the biosensor system. The measurement device applies an open circuit voltage, a voltage that is lower than during concentration measurement, or the like to the electrodes of the sensor chip.