ISFET Solution Detection Circuit with Direct Threshold Voltage Readout
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Solution Overview
Problem
Ion-sensitive field-effect transistors (ISFETs) cannot directly read their threshold voltage due to device structure and circuit limitations, hindering efficient solution detection speed.
Innovation Solution
A solution detection circuit and method that includes an ion-sensitive field-effect transistor, a first reset switch subunit, a synchronous buck switch subunit, a storage capacitor, and an output switch subunit, allowing for direct reading of the threshold voltage by resetting and discharging the gate and drain voltages to the threshold voltage for accurate pH or ion concentration detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pH detection or ion concentration detection through ISFET threshold voltage testing is used, then solution detection can be achieved, but the threshold voltage cannot be directly read due to device structure and circuit characteristics limitations, resulting in reduced detection speed
Solution Approach 1:
The patent introduces an intermediary circuit system comprising a first reset switch subunit, synchronous buck switch subunit, storage capacitor, and output switch subunit. This intermediary circuit acts as a mediator between the ISFET and the reading system, enabling the threshold voltage to be extracted and read directly by controlling the switching operations and capacitor charging/discharging processes, thereby resolving the limitation of indirect measurement
Solution Approach 2:
The patent changes the operational parameters of the ISFET by controlling the gate and drain voltages through the switching subunits. By adjusting the voltage parameters and timing sequences of the switches, the system transforms the ISFET operation to a state where the threshold voltage can be directly observed at the output, converting an indirectly measurable parameter into a directly readable one
2Productivity
If conventional ISFET threshold voltage testing is used, then solution detection can be performed, but the detection speed is reduced due to inability to directly read threshold voltage
Solution Approach 1:
The patent performs preliminary actions by pre-charging the storage capacitor to a known voltage and pre-positioning the switching elements in specific states before the actual measurement. This preliminary setup enables the threshold voltage to be directly captured and read in a single operation cycle, eliminating multi-step measurement procedures and significantly improving detection speed
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
Enables direct and accurate reading of the threshold voltage, improving solution detection speed and accuracy by ensuring the ion-sensitive field-effect transistor turns on and off at the correct voltage levels, thereby enhancing pH or ion concentration detection efficiency.
Implementation Method 1
An ion-sensitive field-effect transistor (ISFET) is a microelectronic ion-selective sensitive element having dual characteristics of electrochemistry and a transistor. At present, the pH detection or the ion concentration detection of a solution can be achieved through a test of a threshold voltage of the ISFET.
Implementation Method 2
The first reset switch subunit is turned on to reset a gate voltage and a drain voltage of the ion-sensitive field-effect transistor to the reference voltage
Implementation Method 3
The first reset switch subunit is turned off, and the synchronous buck switch subunit is turned on, so that the gate voltage and the drain voltage of the ion-sensitive field-effect transistor drop to the threshold voltage of the ion-sensitive field-effect transistor
Implementation Method 4
A first plate of the storage capacitor is connected to the gate of the ion-sensitive field-effect transistor, and a second plate of the storage capacitor is connected to the ground
Data Source
AI summary
Provided are a solution detection circuit and apparatus, a driving method and a solution detection method. The solution detection circuit includes at least one detection unit, the detection unit includes an ion-sensitive field-effect transistor, a first reset switch subunit, a synchronous buck switch subunit, a storage capacitor and an output switch subunit. A threshold voltage of the ion-sensitive field-effect transistor can be directly read.