Pore-Based Microparticle Measurement Without Pump Pulsation
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Solution Overview
Problem
Pump-induced pressure pulsation in pore-based devices degrades the accuracy of microparticle measurements by affecting the microcurrent signal, particularly in the electrical sensing zone method.
Innovation Solution
A microparticle measuring apparatus with a pressure controller that accumulates pressure in a tank prior to measurement, using the stored energy to maintain a stable pressure difference between liquid chambers, eliminating pump-induced pulsation and ensuring a constant flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pump is used to generate pressure difference for driving solution flow through the pore, then particle migration through the pore is enabled, but pump-induced pressure pulsation degrades measurement accuracy
Solution Approach 1:
The pump operates in advance to generate and store pressure in the tank before measurement begins. During measurement, the pump remains stopped and the stored pressure maintains solution flow through the pore, eliminating pump-induced pulsation while preserving particle migration capability.
Solution Approach 2:
A tank is introduced as an intermediary between the pump and the pore-based device. The tank accumulates pressure from the pump and releases it smoothly during measurement, acting as a buffer that decouples the pump's pulsating output from the measurement system, thereby eliminating pressure pulsation effects on microcurrent signals.
2Duration of action of moving object
If the pump operates continuously to maintain solution flow, then particle detection is sustained, but pressure pulsation increases noise in the current signal
Solution Approach 1:
Pressure is generated and stored in the tank before measurement begins. During the measurement period, the pump remains stopped while the stored pressure sustains solution flow and particle migration through the pore, enabling continuous detection without pump-induced noise.
Solution Approach 2:
The pump operates periodically - running before measurement to build pressure, then stopping during measurement to eliminate pulsation. This periodic operation pattern separates the pressure generation phase from the measurement phase, allowing sustained flow without continuous pump operation.
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 enhances measurement accuracy by reducing noise in the current signal, allowing for precise determination of particle size and count, even with a small number of particles.
Implementation Method 1
The pump generates pressure difference between the two liquid chambers in the pore-based device, thereby creating a flow in the solution, and causing the particles contained therein to pass through the pore
Implementation Method 2
During passage of each particle through the pore, the electrolyte solution in the pore will decrease the volume by an amount equivalent to the volume of the particle, thus increasing electric resistance of the pore. The volume (or, particle size) of the particle can therefore be determined, by measuring the electric resistance of the pore
Implementation Method 3
The transimpedance amplifier 210 is structured to convert the microcurrent Is into a voltage signal Vs
Implementation Method 4
The digitizer 230 is structured to convert the voltage signal Vs into digital data Ds
Data Source
AI summary
A pore-based device has a first liquid chamber and a second liquid chamber separated by a partition having a pore. A measuring instrument is structured to measure a current signal flowing between a first electrode provided in the first liquid chamber and a second electrode provided in the second liquid chamber. A pressure controller is structured to generate pressure difference between the first liquid chamber and the second liquid chamber. A tank is connected between a pump and the pore-based device. The pump is structured to remain stopped during the measurement.