Pulsed Pipetting Device Pressure Control
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Solution Overview
Problem
Existing pipetting devices face challenges in achieving high precision and hygiene when dispensing small volumes of liquids, particularly due to contamination risks and inaccuracies in delivering sub-microliter amounts, as well as issues with surface tension and viscosity affecting droplet formation.
Innovation Solution
A pipetting device utilizing a pressure-variable working gas with a pipetting piston and control system that generates precise pressure pulses to aspirate or dispense liquids, minimizing contact with the liquid and employing a magnetic piston for dynamic movement, ensuring accurate and repeatable dispensing of volumes less than 2 µl without contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piezo actuator is used to directly deliver physical impact to the meniscus, then droplet flinging can be achieved, but contamination risk increases due to contact with dosing fluid
Solution Approach 1:
The patent introduces a working gas (air or inert gas) as an intermediary medium between the piston and the dosing liquid. The piston acts on the working gas, which then transmits the pressure impulse to the liquid through the pipetting tip, eliminating direct contact between the piston and liquid while maintaining the droplet flinging effect
Solution Approach 2:
The patent employs pneumatic principles by using compressible working gas to transmit mechanical energy from the piston to the dosing liquid. The pressure pulse generated in the gas phase creates the necessary impulse force without requiring direct mechanical contact with the liquid, thus preventing contamination
2Reliability
If conventional pipetting methods are used for small volumes, then hygiene can be maintained, but accuracy deteriorates due to leakage effects and surface tension
Solution Approach 1:
The patent employs pulsed pressure application instead of continuous pressure control. By applying pressure in short pulses (5-50 ms), the system overcomes surface tension and viscosity effects that dominate in continuous flow, enabling accurate dispensing of sub-microliter volumes while maintaining hygiene through non-contact operation
Solution Approach 2:
The patent changes the pressure application parameters from continuous to pulsed mode, with pulse widths optimized for different liquid viscosities and volumes. This parameter change allows the system to overcome surface tension and leakage effects that interfere with accuracy in conventional continuous pipetting methods
3Speed
If pressure pulses shorter than 40 ms are used, then pipetting speed increases, but control difficulty worsens due to leakage effects
Solution Approach 1:
The patent implements a feedback control system that monitors the actual pressure pulse and adjusts the piston movement accordingly. The control unit receives signals from pressure sensors and position sensors, comparing actual values with target values to compensate for leakage effects and achieve precise pressure control even in short pulse durations
Solution Approach 2:
The patent replaces purely mechanical pressure control with an electronically controlled system that uses sensors and feedback algorithms. This substitution enables precise control of short pressure pulses by measuring actual pressure and position parameters and adjusting the drive mechanism accordingly, reducing the complexity of achieving accurate control
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 highly precise and hygienic pipetting of small volumes with high repeatability, preventing contamination and accurately dispensing sub-microliter amounts by controlling pressure pulses and piston movement, effectively overcoming issues related to surface tension and viscosity.
Implementation Method 1
a pressure sensor for detecting the pressure of the working gas and for outputting a pressure signal indicating the pressure of the working gas to the control device
Implementation Method 2
a pipetting piston movably mounted along the pipetting channel for changing the pressure of the working gas
Implementation Method 3
the amount of metering liquid taken up in the receiving chamber can be changed by changing the pressure of the working gas in the receiving chamber through the pipetting orifice
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3c
AI summary
The invention relates to pipetting device (10) for the pulsed pipetting of dosing liquids in small dose volumes of less than 2 μΙ, wherein the pipetting device (10) comprises: a pipetting channel (11) at least partially filled with working gas (34), a pipetting tip (26), which is accessible through a pipetting opening (30), such that the volume of dosing liquid drawn into the receiving chamber through the pipetting opening (30) can be varied by means of a change in the pressure of the working gas in the receiving chamber, a pipetting piston (14) for changing the pressure of the working gas (34) and accommodated in the pipetting channel so as to be capable of movement along the pipetting channel (11), a motion drive (20) to drive the pipetting piston (14) for movement along the pipetting channel (11), a control device (24) for controlling the motion drive (20), and a pressure sensor (38) for determining the pressure of the working gas, wherein the control device (24) is designed to control the motion drive (20) in order to generate a pressure pulse in the pipetting channel (11) with a pulse duration of no longer than 40 ms on the basis of the pressure signal output by the pressure sensor (38) in such a manner that the pressure of the working gas (34) during the pulse follows a predefined working gas target pressure pulse characteristic.