Segmented Stepped Piston for Pipette Blowout Accuracy
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Solution Overview
Problem
Traditional air displacement pipettes have a short blowout stroke, which is insufficient to fully discharge adhering liquid from the pipette tip, leading to inaccuracies in liquid dispensing, especially in low-volume pipettes, and existing solutions either increase complexity or size.
Innovation Solution
A handheld pipette with a segmented, stepped piston and dual piston seals, where the wider proximal segment of the piston engages during the blowout stroke to increase air volume and velocity, enhancing the ability to remove adhering liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single-seal piston design is used, then the pipette structure remains simple, but the blowout stroke is insufficient to fully discharge adhering liquid
Solution Approach 1:
The piston is divided into two distinct segments: a first seal segment and a second seal segment. Each segment independently engages with the shaft to provide sealing during different phases of the stroke. This segmentation allows the blowout stroke to engage the second seal segment for enhanced liquid discharge while the first seal segment provides sealing during the main stroke, thus improving liquid discharge completeness without requiring a completely complex new structure.
Solution Approach 2:
The piston design incorporates dynamic engagement where the first and second seal segments are selectively engaged at different phases of the stroke. During the main stroke, the first seal segment is engaged, and during the blowout stroke, the second seal segment is engaged. This dynamic switching allows the system to optimize performance for different operational phases without increasing overall structural complexity.
2Quantity of substance
If the blowout stroke is extended to increase air displacement, then adhering liquid can be better discharged, but the pipette size increases
Solution Approach 1:
The piston features local quality variations with two seal segments of different sizes and sealing characteristics. The second seal segment is specifically designed with different dimensions than the first, allowing it to displace additional air volume during the blowout stroke. This localized differentiation enables increased air displacement during blowout without requiring a uniform increase in the entire piston or pipette size.
Solution Approach 2:
Instead of extending the stroke length in one dimension to increase air displacement, the invention uses a second seal segment with different radial dimensions. The second seal segment has a different diameter than the first, allowing it to displace more air volume during the blowout stroke without increasing the axial length of the piston or pipette body.
3Reliability
If a second seal segment is added to the piston, then enhanced blowout performance is achieved, but manufacturing complexity increases
Solution Approach 1:
The piston is segmented into two seal segments that can be manufactured as separate components or as distinct sections of a unified piston body. This segmentation allows for specialized manufacturing techniques to be applied to each segment independently, optimizing the sealing surfaces while maintaining overall manufacturability. The segments are designed to fit together in a standardized manner, simplifying assembly.
Solution Approach 2:
The two seal segments are designed to work together within the same piston structure, with each segment serving multiple functions. The first seal segment provides sealing during the main stroke, while the second seal segment provides enhanced sealing during the blowout stroke. Both segments share common mounting features and sealing principles, allowing for standardized manufacturing processes to be applied across both segments.
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 enhanced blowout stroke effectively discharges adhering liquid without increasing the pipette's complexity or size, improving the accuracy of liquid dispensing in low-volume pipettes.
Implementation Method 1
The seal between the piston and the shaft is generally formed with a compressed O-ring, a skirted seal, a lip seal, or a similar structure, fabricated from a material that provides satisfactory long-term performance.
Data Source
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AI summary
An air displacement pipette includes a segmented, stepped piston configured to displace additional air at a higher velocity during a blowout stroke, thereby enabling improved dispensing accuracy by more completely dislodging adhering liquid from a pipette tip following the preceding dispensing stroke.