Biosensor Reference Terminal Eliminates Line Resistance Errors
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Solution Overview
Problem
Conventional biosensor devices face errors in blood glucose level measurements due to line resistance in conductive lines, which increases with miniaturization, and are costly due to the use of noble metals like platinum, gold, or silver.
Innovation Solution
A biosensor design with a working electrode, counter electrode, and a reference terminal, where the reference terminal is connected to either the working electrode or counter electrode, allowing assays without being influenced by line resistance, using inexpensive metals like aluminum or copper for conductive lines and optimizing electrode configurations for high precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If noble metals like platinum, gold, or silver are used for conductive lines to reduce line resistance, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies the disposable principle by designing a biosensor that uses inexpensive conductive lines made of aluminum or copper instead of noble metals. The entire biosensor including the conductive lines is designed as a disposable single-use device, eliminating the need for expensive noble metals while maintaining measurement precision through the four-terminal configuration that compensates for line resistance effects.
2Productivity
If biosensor size is reduced for miniaturization, then device portability and productivity are improved, but line resistance increases causing measurement errors
Solution Approach 1:
The patent applies segmentation by dividing the electrical connection into two separate paths: one for current flow (working electrode to counter electrode) and another for voltage reference (reference terminal to counter electrode). This four-terminal configuration separates the measurement function from the current carrying function, allowing miniaturization without increasing line resistance errors since the voltage reference path does not carry current.
Solution Approach 2:
The reference terminal acts as an intermediary that provides a voltage reference point without carrying measurement current. By introducing this intermediate element, the patent enables accurate voltage measurement despite the presence of line resistance in miniaturized conductive lines, thus maintaining measurement precision while enabling device miniaturization.
3Device complexity
If conventional two-terminal configuration is used to simplify device structure, then device complexity is reduced, but measurement precision deteriorates due to line resistance errors
Solution Approach 1:
The patent segments the electrical connection into distinct functional paths by introducing a reference terminal. The current path (working electrode to counter electrode) is separated from the voltage reference path (reference terminal to counter electrode), allowing independent optimization of each function and eliminating the coupling between current flow and voltage measurement that causes errors in two-terminal configurations.
Solution Approach 2:
The counter electrode serves multiple functions: it acts as both the counter electrode for current flow and as part of the voltage reference path through the reference terminal. This multi-functionality reduces the need for additional components while maintaining the precision benefits of the four-terminal configuration.
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
The biosensor achieves high-precision glucose level measurements without line resistance errors, reducing manufacturing costs and enabling further miniaturization without compromising assay precision.
Implementation Method 1
a reference terminal connected to one or both of the working electrode and the counter electrode, through which substantially no current flows during an assay
Implementation Method 2
a working electrode to be in contact with an assayed fluid during an assay; a counter electrode to be in contact with the assayed fluid during an assay
Data Source
AI summary
A biosensor includes a working electrode 101, a counter electrode 102 opposing the working electrode 101, a working electrode terminal 103 and a working electrode reference terminal 10 connected to the working electrode 101 by wires, and a counter electrode terminal 104 connected to the counter electrode 102 by a wire. By employing a structure with at least three electrodes, it is possible to assay a target substance without being influenced by the line resistance on the working electrode side.