Dispensing Assembly Cleaning via Pressurized Gas Purge and Pulse Flow
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Solution Overview
Problem
Current dispensing systems for small liquid volumes face challenges in minimizing carryover, which is the residual contamination of sample liquids, especially when switching between different samples, leading to reduced productivity due to lengthy washing cycles.
Innovation Solution
A method and system that uses pressurized gas to purge and then cleaning liquid to flush the dispensing assembly, incorporating pulse flow to effectively scour and remove contaminants, allowing for reduced washing time and enhanced productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional washing cycles are used to reduce carryover, then cleaning effectiveness is improved, but productivity deteriorates due to lengthy washing time
Solution Approach 1:
The patent applies pneumatic pressure to force cleaning solution through the dispensing assembly at high velocity, creating a hydraulic flushing action that removes contaminants more effectively and quickly than gravity-based washing, thereby reducing carryover while shortening cleaning time
Solution Approach 2:
The cleaning process uses periodic pulsing of cleaning solution followed by periodic purging with gas, creating alternating cycles of wet cleaning and dry purging that efficiently remove contaminants without requiring continuous washing, thus reducing overall cleaning time while maintaining effectiveness
2Reliability
If multiple cleaning cycles are performed to ensure low carryover, then cleaning effectiveness is improved, but loss of time increases
Solution Approach 1:
By using pressurized gas to force cleaning solution through the system at high velocity, the patent achieves more effective cleaning in fewer cycles, reducing the total time required while maintaining low carryover levels
Solution Approach 2:
The cleaning process maintains continuous useful action by immediately following the cleaning pulse with a purging pulse, ensuring that cleaning solution is constantly moving through the system and contaminants are continuously removed without idle time between cleaning cycles
3Productivity
If pulse flow is used to scour contaminants, then cleaning efficiency is improved, but device complexity increases
Solution Approach 1:
The pulse flow is achieved through simple periodic switching between cleaning solution delivery and gas purging, using basic temporal control rather than complex flow regulation mechanisms, thereby maintaining simplicity while improving cleaning efficiency
Solution Approach 2:
The system uses pneumatic pressure pulses to create the scouring action, leveraging the simplicity of pressure-based flow control rather than complex mechanical or electronic flow regulation, thus improving efficiency without significantly increasing device complexity
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
Significantly reduces carryover contamination, enhancing the productivity of dispensing systems by minimizing the time required for washing cycles while maintaining effective cleaning of dispensing tips.
Implementation Method 1
delivering pressurised gas through the contaminable portion of the dispenser to expel liquid and fill with the purging gas
Implementation Method 2
delivering pressurised cleaning liquid through the contaminable portion to flush it
Data Source
AI summary
There is provided a method of cleaning a dispensing assembly for small liquid droplets less than 50 μl and even as low as 10 nl. A purging step with pressurized gas followed by a cleaning step using a suitable cleaning liquid is carried out a number of times.