Non-contact Printing System Gentle Mixing via Pressure Gradient
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Solution Overview
Problem
Current non-contact liquid printing systems face challenges in maintaining stable cell concentration and preventing cell damage due to sedimentation and clumping, especially in low liquid volumes, and existing mixing methods like recirculation circuits and stirrers can cause shear stress and are not suitable for all cell types.
Innovation Solution
A non-contact printing system that uses aspiration and dispensing of liquid in the reservoir to mix biological samples, employing a piston or inflatable element to create gentle agitation, preventing sedimentation and cell clumping without inducing mechanical stress, with a frequency of about two to three minutes to maintain cell integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If recirculation circuits with pumps are used to mix cells, then mixing effectiveness is improved, but mechanical shear stress increases causing cell damage
Solution Approach 1:
The patent replaces the mechanical pump-based recirculation system with a pressure-driven flow system. A pressure source (e.g., compressed gas) applies pressure to the liquid surface in the reservoir, creating gentle convection currents that mix cells without the high shear stresses generated by mechanical pumps and recirculation circuits.
Solution Approach 2:
The patent uses pneumatic pressure applied to the liquid surface to drive mixing. A gas pressure source creates pressure-driven flow patterns within the reservoir that gently agitate the cell suspension, achieving mixing effectiveness while avoiding the mechanical shear damage associated with traditional pump-based systems.
2Stability of the object's composition
If rotating stirrers are used within the reservoir, then mixing is improved, but device complexity and shear stress increase
Solution Approach 1:
The patent removes the rotating stirrer from inside the reservoir entirely. Instead of placing a mechanical mixing device within the cell suspension, the invention applies pressure to the liquid surface from above, allowing pressure-driven convection to perform the mixing function without introducing complex mechanical components into the reservoir.
Solution Approach 2:
The patent replaces the mechanical rotating stirrer with a pressure-driven flow system. By applying gas pressure to the liquid surface, the system creates gentle convection currents that mix cells without requiring complex mechanical stirring devices within the reservoir, thereby reducing device complexity and mechanical shear stress.
3Stability of the object's composition
If frequent mixing is performed to prevent sedimentation, then cell concentration stability is improved, but cell damage risk increases
Solution Approach 1:
The patent implements periodic mixing cycles where gas pressure is applied intermittently rather than continuously. The pressure source is activated at scheduled intervals to create gentle convection currents that prevent sedimentation, then deactivated to allow the system to settle, providing adequate mixing frequency while avoiding over-handling damage to cells.
Solution Approach 2:
The patent controls the pressure parameters (magnitude and duration) to optimize mixing effectiveness while minimizing cell stress. By adjusting the gas pressure levels and application timing, the system achieves sufficient mixing to prevent sedimentation while keeping individual mixing events gentle enough to avoid cell damage from over-handling.
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 ensures stable cell concentration at the printer nozzle over time, preventing cell damage and maintaining reagent quality by effectively mixing and re-suspending cells without the need for large volumes or shear-inducing methods.
Implementation Method 1
fluid is brought by capillary feed 5 to the rear face 9a of a perforate membrane 9
Implementation Method 2
A vibration means or actuator 13 is operable by an electronic circuit 15 which derives electrical power from a power supply 17 to vibrate the perforate membrane 9, producing droplets of fluid 19
Implementation Method 3
The actuator 13 comprises a piezoelectric and/or electrostrictive actuator
Implementation Method 4
The actuator 13 comprises a piezoelectric and/or electrostrictive actuator
Implementation Method 5
Liquid mixing is achieved through aspiration and subsequent dispense of a volume of liquid in the printing liquid reservoir
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A non-contact printing system comprising: a printing liquid reservoir configured to contain in use a printing liquid defining a first printing liquid surface; an expansion chamber in fluid communication with the printing liquid, the expansion chamber including a bore; and an aspirator element in fluid communication with the expansion chamber, the aspirator element including a piston arranged to reciprocate in the bore, wherein in use: the piston is movable from a first position to a second position to reduce a pressure of a gas in the expansion chamber such that a pressure head of the printing liquid moves the printing liquid from the printing liquid reservoir to the expansion chamber to cause a second printing liquid surface defined by the expansion chamber to rise in the expansion chamber from a first level to a second level; and the piston is movable from the second position to the first position to restore the pressure of the gas in the expansion chamber such that the pressure head of the printing liquid moves the printing liquid from the expansion chamber to the printing liquid reservoir returning the second printing liquid surface from the second level to the first level, so as to cause mixing of the printing liquid in the printing liquid reservoir.