Nanopore Current Measurement Calibration for Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional microparticle measurement systems using the electrical sensing zone method face challenges in achieving a broad bandwidth for accurate measurement of particle shape due to parasitic capacitance, which results in unstable output waveforms and limited ability to extract detailed characteristic information.
Innovation Solution
A measurement apparatus with a transimpedance amplifier and voltage source that can switch between normal and calibration modes, allowing for calibration of circuit constants to optimize bandwidth and stability, using a calibration voltage with an AC component to correct for parasitic capacitance and improve waveform accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transimpedance amplifier is used to measure microscopic current through the nanopore, then measurement sensitivity is improved, but bandwidth is reduced due to parasitic capacitance
Solution Approach 1:
The patent applies a calibration voltage with AC component to deliberately excite the parasitic capacitance, measuring its effect and then compensating for it. The harmful parasitic capacitance is converted into a measurable signal that can be corrected through calibration, transforming the problem into a solvable measurement task.
Solution Approach 2:
The patent changes the operating parameters by applying different voltages (DC bias voltage for normal operation, calibration voltage with AC component for calibration) to the nanopore device. This allows separate measurement of the parasitic capacitance effect and the actual particle signal, enabling compensation and optimization of both bandwidth and measurement precision.
2Productivity
If the nanopore device operates at high speed to capture particle information, then productivity is improved, but waveform distortion increases due to parasitic capacitance
Solution Approach 1:
The calibration process deliberately excites the parasitic capacitance with AC component to measure and compensate its distorting effect. This transforms the harmful waveform distortion into a quantifiable and correctable parameter, allowing high-speed operation without sacrificing waveform accuracy.
Solution Approach 2:
The system uses feedback by measuring the effect of parasitic capacitance through calibration and applying compensation to correct the measured signals. This feedback mechanism enables the system to maintain waveform accuracy even at high measurement speeds where distortion would normally occur.
3Ease of operation
If standard particles are used for calibration, then measurement procedure is simplified, but detailed particle shape information is lost
Solution Approach 1:
The patent turns the limitation of standard particle calibration into an opportunity by adding AC component calibration that specifically targets parasitic capacitance measurement. This additional calibration step, while more complex than standard methods, enables the system to preserve detailed particle shape information that would otherwise be lost in conventional approaches.
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 system achieves reduced waveform distortion, enabling accurate measurement of particle shape and diameter distribution, and is capable of compensating for variations in nanopore devices and reagents, supporting high-speed operation with stability and wide bandwidth.
Implementation Method 1
a transimpedance amplifier configured to convert the current signal into a voltage signal
Implementation Method 2
The voltage source 220 generates an electric potential difference Vb between the electrode pair 106 and 108. The electric potential difference Vb functions as a driving source of the electrophoresis
Implementation Method 3
the particles 4 migrate by electrophoresis from a given space to the other space via the aperture 104
Implementation Method 4
by measuring the electrical resistance of the aperture, this arrangement is capable of measuring the volume of the particle that passes through the aperture
Data Source
AI summary
A nanopore device measures a current signal Is that flows through the nanopore device, which has an aperture and an electrode pair. A transimpedance amplifier converts the current signal Is into a voltage signal Vs. A voltage source is configured to apply a DC bias voltage Vb across the electrode pair in a normal measurement mode, and to apply a calibration voltage Vcal across the electrode pair in a calibration mode. In the calibration mode, at least one circuit constant of a measurement apparatus is calibrated based on the output signal Vs of the transimpedance amplifier and the calibration voltage Vcal.