Outer Piston Pipetting Apparatus for Expanded Fluid Volume
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Solution Overview
Problem
Pipetting apparatuses have limited metering fluid capacity due to small work space volume changes caused by the relative motion of piston and cylinder, and the installation of pressure sensors further reduces this capacity by occupying valuable space.
Innovation Solution
Designing the piston as an outer piston that surrounds the cylinder in the longitudinal end region, allowing for a larger change in work space volume under the same lift, and integrating pressure sensors on the piston to avoid interference with the metering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sensors are installed on each pipette channel laterally, then quality monitoring of the metering process is enabled, but the installation space is taken from the piston-cylinder system which decreases the largest possible change of the work volume
Solution Approach 1:
The pressure sensor is integrated into the piston structure, specifically arranged in the region of the piston head or forming part of it. This nesting approach allows the sensor to be housed within the existing piston volume without requiring additional lateral space, thereby maintaining the full work volume change capacity while enabling quality monitoring through pressure measurement of the work fluid
Solution Approach 2:
The pressure sensor functionality is merged with the piston structure by providing the sensor in the region of the piston head or forming part of it. This combination eliminates the need for separate lateral sensor mounting and allows both the metering function and quality monitoring function to coexist within the same spatial envelope
2Volume of moving object
If the piston is designed as an inner piston guided in the interior of the cylinder, then the structure is compact, but the change in work space volume under the same lift is limited
Solution Approach 1:
Instead of the conventional inner piston design where the piston is guided inside the cylinder, the patent inverts the configuration by designing the piston as an outer piston that surrounds the cylinder. This inversion allows the piston to have a larger cross-sectional area relative to the cylinder, thereby increasing the work volume change capacity (volume of cylinder wall cross-section multiplied by lift) while maintaining structural integrity through the cylinder being received in the hollow of the piston
Data Source
AI summary
For aspiration and dispensation of a metering fluid, a pipetting apparatus comprises a work fluid which differs from the former, the work fluid being accommodated in a work space with a variable volume which extends along a channel axis and, with reference to the latter, is formed by a piston-cylinder system at least along an axial section of the channel axis, having a cylinder which delimits the work space along a cylinder section in the radial direction and a piston which delimits the work space in a first axial direction, the cylinder and the piston being arranged so that they can move with respect to each other such that the piston-cylinder system has an axial longitudinal end region for metering, which is open for aspiration and dispensation, and an axial longitudinal end region for work which is closed by the piston, the piston being designed as an outer piston and surrounding the cylinder on the outside in the longitudinal end region for work of the piston-cylinder system.