Pipette Pressure Chamber Volume Control for Suction Precision
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Solution Overview
Problem
Existing pipettes face challenges in accurately controlling the suction amount of liquids due to variations in liquid separation timing and flow into the capillary, leading to inconsistencies in measurement precision and volume accuracy.
Innovation Solution
The pipette employs a control unit that generates specific drive signals to adjust the volume of a pressure chamber within the capillary, incorporating a brake signal to manage the suction process, ensuring precise control over the suction amount by adjusting the pressure chamber's volume and reducing liquid flow into the capillary after initial suction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the volume of the pressure chamber is increased to suction more liquid, then the suction amount increases, but the liquid flow into the capillary becomes uncontrolled and measurement precision decreases
Solution Approach 1:
The brake signal is applied in advance before the liquid separation step to suppress liquid flow into the capillary before measurement. This preliminary action prevents excessive liquid from entering the capillary, ensuring that the liquid amount remains within the accurate measurement range of the meniscus detection section, thereby resolving the contradiction between suction quantity and measurement precision.
Solution Approach 2:
The system uses meniscus detection to monitor the liquid level in the capillary and provides feedback to the control unit. Based on this feedback, the control unit adjusts the pressure chamber volume and applies brake signals to maintain the liquid level within the optimal measurement range, ensuring both adequate suction amount and high measurement precision.
2Reliability
If the suction process is extended to ensure complete liquid collection, then the liquid collection completeness improves, but the timing variation increases and consistency decreases
Solution Approach 1:
The system employs periodic pressure changes in the pressure chamber, including suction phases and brake phases, to control liquid movement. This periodic action ensures complete liquid collection while maintaining consistent timing through automated control, resolving the contradiction between collection completeness and timing consistency.
Solution Approach 2:
The control unit dynamically changes the volume of the pressure chamber during the suction process and applies brake signals at specific times. By changing the pressure chamber volume parameter and timing the brake signal application, the system ensures complete liquid collection while reducing timing variations and improving operational consistency.
3Measurement precision
If the pressure chamber volume is reduced to improve measurement accuracy, then the measurement precision improves, but the suction capability decreases
Solution Approach 1:
The liquid handling process is segmented into distinct phases: suction phase where the pressure chamber volume is increased for adequate liquid collection, and measurement phase where the volume is reduced for precise measurement. The brake signal separates these phases, allowing the system to achieve both sufficient suction capability and high measurement precision at different stages.
Solution Approach 2:
The pressure chamber volume is made dynamic rather than fixed. The control unit adjusts the volume during the suction process to ensure adequate liquid collection, then reduces it before measurement to improve precision. This dynamic adjustment resolves the contradiction between suction capability and measurement precision.
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 precision and reduces variations in suction amounts, allowing for more accurate liquid handling and improved operational consistency.
Implementation Method 1
drives a pump action device to generate a negative pressure in an internal portion of a capillary and thereby suction a liquid into the capillary
Implementation Method 2
an electrostatic actuator which configures a portion of an inner surface of the vessel. Due to flexural deformation of a portion of the inner surface of the vessel by the electrostatic actuator, the liquid is suctioned or ejected from the nozzle cap
Data Source
Figure 1
Figure 2
Figure 3A~3E
AI summary
In a capillary of a pipette, a first end and a second end forming two ends in a longitudinal direction are opened. A pressure chamber is communicated through the second end with an internal portion of the capillary. A driving part changes a volume of the pressure chamber. A control part outputs a first signal driving the driving part so that the volume of the pressure chamber increases and a liquid is suctioned from the first end. A suction signal in the first signal drives the driving part so that the volume of the pressure chamber increases from a volume before suction of the liquid by a first increase amount to become a first post-suction volume. A brake signal is output following the suction signal and drives the driving part so that the volume of the pressure chamber is reduced from the first post-suction volume by an reduction amount which is smaller in absolute value than the first increase amount.