Multi-Channel Pipette Piston Mounting to Limit Rake Effect
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Solution Overview
Problem
Multi-channel pipettes suffer from the 'rake effect' and increased friction due to parasitic torque, leading to reduced gravimetric performance and ergonomic issues, particularly in manual, motorized, or hybrid systems.
Innovation Solution
A multi-channel pipetting system with a piston holder and guide rod design that allows pistons to pivot around an axis of rotation, using elastic return means to mitigate torque and reduce friction, incorporating flexible connections to limit the rake effect and improve sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid mechanical connection is used to mount the piston on the piston holder, then the rigidity of the connection is improved, but parasitic torque is generated causing the rake effect and increased friction
Solution Approach 1:
The patent changes the mechanical parameter from rigid connection to flexible connection. The flexible connection allows the piston to pivot relative to the piston holder, transforming the rigid mechanical link into a dynamic joint that can accommodate movement while maintaining functional integrity.
Solution Approach 2:
The patent introduces dynamic behavior to the piston mounting system. The piston is no longer fixed rigidly but can pivot dynamically around an axis, allowing it to adapt to the movement trajectory and reduce parasitic torque generation during operation.
2Stability of the object's composition
If the piston holder is rigidly constrained, then the structural stability is improved, but friction and jamming of moving elements increases
Solution Approach 1:
The patent makes the piston mounting dynamic by allowing pivoting motion. This dynamic capability enables the piston to self-adjust during movement, reducing friction between the piston holder and surrounding elements, thereby improving ease of operation while maintaining structural stability through the guide rod constraints.
3Manufacturing precision
If the piston is rigidly mounted, then the mechanical precision is improved, but the rake effect increases reducing gravimetric performance
Solution Approach 1:
The patent changes the mounting parameter from rigid to flexible, allowing the piston to pivot and follow the optimal movement path. This reduces the rake effect (volume difference between extreme channels) and improves gravimetric performance while maintaining sufficient mechanical precision through controlled pivoting around a defined axis.
4Ease of operation
If elastic return means are introduced to mitigate torque, then the ergonomics are improved, but the device complexity increases
Solution Approach 1:
The elastic return means provide self-service functionality by automatically compensating for parasitic torque and maintaining piston positioning without external intervention. The elastic element inherently absorbs torque variations and maintains the piston in its operational position, improving ergonomics while adding minimal complexity compared to active control systems.
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
Enhances gravimetric performance and ergonomics by reducing pipetting and purging forces, simplifying design, and increasing the lifespan of piston seals while maintaining sealing integrity under autoclave conditions.
Implementation Method 1
elastic return means forcing the piston head upwards against the piston holder
Data Source
AI summary
A device for a multi-channel pipetting system, comprising a piston holder, a guide rod of the piston holder, which guide rod is mounted slidably in a guide member, a plurality of pistons having a bottom end housed slidably in a suction chamber, and a piston head mounted on the piston holder by way of a mechanical connection. The mechanical connection comprises two contact points which conjointly define a piston-head rotation axis oriented orthogonally with respect to the transverse direction and to the longitudinal central axis of the pipetting system, and the device additionally comprises, associated with the piston, return spring which force the piston head upward against the piston holder, so as to establish the two contact points.