MOS Transistor Interface for Amperometric Sensor Signal Conditioning
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Solution Overview
Problem
Existing electronic devices for reading signals from electro-chemical amperometric sensors are bulky, energy-intensive, require double power supplies, and are not adaptable to different dynamic ranges of sensor operations, limiting their versatility and cost-effectiveness.
Innovation Solution
A compact electronic device using a single type of MOS transistors (either N-MOS or P-MOS) with a non-linear gain and current offset, allowing for efficient detection of a wide range of currents, adaptable to various sensors, and compatible with Organic Thin Film Transistors technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional potentiostat-galvanostat equipment is used, then accurate reading of Faraday current and constant potential maintenance are achieved, but device size and cost increase
Solution Approach 1:
The patent divides the traditional potentiostat-galvanostat functions into separate modular components: an operational amplifier for potential control, a trans-impedance amplifier for current-to-voltage conversion, and a readout circuit. This segmentation allows each component to be optimized independently and integrated into a compact form factor while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces a trans-impedance amplifier as an intermediary component between the electrochemical cell and the readout circuit. This intermediary converts the small Faraday current into a measurable voltage signal while maintaining signal integrity, enabling accurate measurement without requiring bulky traditional instrumentation.
2Measurement precision
If traditional potentiostat-galvanostat equipment is used, then accurate reading of Faraday current and constant potential maintenance are achieved, but device cost increases
Solution Approach 1:
The patent employs readily available, low-cost operational amplifiers and standard electronic components to build the potentiostat circuitry. By using commercially available off-the-shelf parts rather than specialized expensive instrumentation, the system achieves accurate measurements at a fraction of the cost of traditional equipment.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms found in traditional potentiostats with electronic control circuits. Operational amplifiers provide automatic feedback control for potential maintenance, eliminating the need for manual adjustments and reducing both cost and complexity while maintaining measurement precision.
3Reliability
If double power supply is used, then operational amplifiers can function properly, but energy consumption increases
Solution Approach 1:
The patent modifies the power supply configuration from a traditional dual-rail supply to a single-rail supply with virtual ground technique. By changing the reference potential and using capacitive coupling for AC signals, the operational amplifiers can function correctly with reduced power consumption while maintaining signal integrity and system reliability.
4Device complexity
If fixed gain circuit is used, then circuit design is simple, but adaptability to different dynamic ranges is reduced
Solution Approach 1:
The patent implements a variable gain amplifier with programmable gain settings that can be adjusted through software control. This dynamic gain adjustment allows the same circuit to adapt to different sensor types and measurement ranges, providing versatility without requiring multiple dedicated circuits for each application.
Solution Approach 2:
The patent designs a universal readout circuit that can interface with multiple types of electrochemical sensors and measurement configurations. Through programmable parameters and adjustable gain stages, a single circuit design serves multiple functions across different dynamic ranges, eliminating the need for application-specific custom designs.
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 device provides improved dynamic range, reduced energy consumption, and stability, especially for detecting small currents, while being cost-effective and versatile for different electro-chemical sensors, with adjustable gain and offset for optimal performance.
Implementation Method 1
an operational amplifier, adapted to operate in a feedback configuration to supply the constant cell electrical potential
Implementation Method 2
a first MOS transistor, having a first MOS gate terminal connected to the output of the operational amplifier, a first MOS drain terminal and a first MOS source terminal connected to the collector electrode to receive or supply a first MOS transistor channel current representative of the cell current
Implementation Method 3
a second MOS transistor, having a second MOS gate terminal connected to the output of the operational amplifier and to the first MOS gate terminal, a second MOS source terminal and a second MOS drain terminal; the value of the first resistance is lower than the cell impedance so that the second MOS transistor channel current depends on the first MOS transistor channel current through a non-linear gain
Data Source
AI summary
Electronic devices and methods for reading an output signal and controlling a three-electrode electro-chemical amperometric sensor include an operational amplifier having a non-inverting input adapted to receive a biasing electric potential and an inverting input connectable to a reference electrode of the sensor. The devices further include one or more MOS transistors connected to the operational amplifier, with a first MOS transistor connectable to the collector electrode of the sensor to receive or supply a MOS transistor channel current representative of the cell current generated in the sensor, and a second MOS transistor connectable to a reference voltage by a conductor or a resistor. The resistance is lower than the cell impedance such that the current in the second MOS transistor channel depends on the current in the first MOS transistor channel through a nonlinear gain dependent on the resistor.