HPLC Pump Pressure Control via Removable Head Strain Gauge
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Solution Overview
Problem
High performance liquid chromatography (HPLC) systems face challenges in delivering reliable pressure control due to varying pressure profiles across different pump barrels, making it difficult to identify and control fluid pressure accurately, especially when dealing with nanoliter-sized volumes.
Innovation Solution
A pump design featuring a pump main body and a removable pump head with a strain gauge that transmits pressure data through electrical connectors, allowing for precise pressure measurement and control, and a memory device for calibration, enabling reliable pressure output and portability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional HPLC pumps are used, then flow rates measured in cubic centimeters per minute are delivered, but pressure control reliability deteriorates due to varying pressure profiles across different pump barrels
Solution Approach 1:
The system performs preliminary calibration for each pump head to establish its unique pressure profile before use. The microprocessor stores calibration data and uses it to compensate for barrel variations, ensuring reliable pressure control from the start of operation without requiring manual adjustment during operation.
Solution Approach 2:
A pressure sensor provides real-time feedback on the actual pressure within the barrel. The microprocessor continuously monitors this feedback and adjusts the plunger position and speed to maintain the desired pressure profile, compensating for variations between different pump barrels and ensuring consistent performance.
2Adaptability or versatility
If pump barrels vary from pump to pump, then each has a unique pressure profile, but this prevents a common profile from being accurate
Solution Approach 1:
Each pump head undergoes preliminary calibration to map its unique pressure profile. The system stores these individual calibration characteristics and uses them to accurately interpret pressure sensor readings, transforming the problem of variability into a solvable calibration issue.
Solution Approach 2:
The system changes the parameter of pressure profile by applying unique calibration factors to each pump head. The microprocessor uses these calibration parameters to adjust and normalize pressure readings from different barrels, enabling accurate pressure measurement despite physical variations between pump heads.
3Productivity
If HPLC systems use large sample volumes and mobile phase volumes, then analysis can be performed, but fluid consumption increases
Solution Approach 1:
The patent replaces conventional large-scale mechanical HPLC pumping with a microfluidic pump system. This substitution enables the same analytical function to be performed with nanoliter volumes, dramatically reducing fluid consumption while maintaining analysis capability through precise pressure control at the microscale.
4Measurement precision
If pressure sensor is placed within the cylinder, then pressure can be measured, but the system requires electrical connections that may complicate the design
Solution Approach 1:
The patent uses a flexible printed circuit board as an intermediary to connect the pressure sensor and other electronic components within the pump head to the external control system. This flexible circuit board simplifies the electrical connection architecture, allowing sensors to be positioned optimally for measurement while maintaining electrical connectivity without rigid wiring constraints.
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 solution provides a lightweight, robust flow system capable of delivering precise pressure control and efficient operation with minimal fluid consumption, suitable for field-portable HPLC units, allowing for reliable pressure output and efficient operation with nanoliter volumes.
Implementation Method 1
a strain gauge affixed to the pump head adjacent the pump head first side of the pump head body at the measurement surface and adapted to transmit a signal indicative of the deflection
Implementation Method 2
a seal separated from the main body face by a spring
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A pump for high-pressure and/or nano-scale volumes permits identification of the internal pressure of the pump.