Microplate Washer Waste Container Fill Detection via Pressure Equalization
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Solution Overview
Problem
Existing methods for determining the fill level in waste containers of microplate washing devices are prone to errors due to exposure to biological samples, which can cause float-based sensors to malfunction, leading to potential overflow and improper disposal of infectious materials.
Innovation Solution
A method using a microplate washing device with a pressure sensor and pump to measure the time it takes for air pressure in the waste container to equalize within a predetermined range, allowing for reliable determination of fillability without the need for additional sensors or complex modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If float-based sensors are used to determine fill level in waste containers, then the fill level can be directly monitored, but the sensors are exposed to biological samples and can malfunction
Solution Approach 1:
The patent introduces an intermediary system consisting of a pump, pressure sensor, and control unit that indirectly measures fill level by monitoring pressure changes in the waste container. Instead of placing a sensor directly in the waste container where it would contact biological samples, the system uses a pressure sensor connected through a line to monitor pressure variations caused by liquid volume changes, thereby eliminating direct exposure while maintaining measurement capability
Solution Approach 2:
The patent replaces the mechanical float-based sensor system with a pneumatic pressure measurement system. Instead of using a mechanical float that physically contacts the liquid, the system uses a pump to generate negative pressure and a pressure sensor to detect pressure changes, substituting mechanical direct-contact measurement with pneumatic indirect measurement
2Measurement precision
If additional sensors are added to waste containers to improve fill level monitoring, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent makes the pump serve multiple functions: it is used both for the primary function of aspirating liquids from samples and for the secondary function of generating negative pressure to enable fill level measurement. The pressure sensor similarly serves dual purposes by monitoring both waste container pressure for fill level determination and potentially detecting leaks. This multi-functionality eliminates the need for separate dedicated measurement components
Solution Approach 2:
The system uses the existing infrastructure of the microplate washing device (pump, lines, pressure sensor) to perform the fill level measurement function. The pump's aspiration mechanism and pressure sensor, already present for liquid handling, are utilized to indirectly measure fill level by monitoring pressure changes, allowing the system to self-determine fill status without external or additional specialized sensors
3Reliability
If waste containers are made airtight to enable pressure-based measurement, then measurement reliability improves, but the risk of overflow due to pressure buildup increases
Solution Approach 1:
The patent implements dynamic pressure control by continuously monitoring pressure levels and adjusting the pump operation accordingly. The system maintains negative pressure within a safe range by activating the pump only when needed and stopping before dangerous vacuum levels are reached. The control unit dynamically adjusts the aspiration process based on real-time pressure feedback, preventing both overflow and excessive vacuum conditions
Solution Approach 2:
The system employs feedback control by using the pressure sensor to continuously monitor the pressure in the waste container and feeding this information back to the control unit. Based on this feedback, the control unit adjusts the pump operation to maintain pressure within safe limits, preventing overflow while enabling accurate fill level measurement through pressure changes
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 method provides a reliable and easy-to-implement solution for determining the remaining volume in waste containers, reducing the risk of overflow and ensuring safe disposal of biological waste by using standard components of the microplate washer.
Implementation Method 1
a pump (3) for generating a negative pressure in the waste container (1)
Implementation Method 2
the pressure sensor (4) being operatively connected to the waste container (1) for determining an air pressure in the waste container (1)
Implementation Method 3
measuring a time for an equalization of the air pressure in the waste container (1)
Data Source
Figure 1~3
Figure 4~5
Figure 6
AI summary
This relates to a method for determining the fillability of a waste container from a microplate washer. The microplate washer comprises at least one washing needle for aspirating liquids, a substantially airtight waste container for collecting the aspirated liquids, a pump for generating a vacuum in the waste container and for determining the atmospheric pressure in this waste container, a pressure sensor connected to it, and a sensor controller. The pump and the washing needle are each connected to the waste container via at least one line. The microplate washer includes a valve on the line between the washing needle and the waste container for shutting off this line.The inventive method is characterized by the following steps: a) closing the valve between the washing needle and the waste container and generating a vacuum in a predetermined vacuum test area below ambient pressure, b) closing a further valve between the waste container and the pump, c) opening the valve between the washing needle and the waste container and triggering a vacuum release in the waste container, d) measuring a test time for the vacuum release in the vacuum test area, e) comparing the test time with a threshold time defined before the measurement, and f) deciding that the waste container cannot be filled if the test time is less than this threshold time, or that the waste container can be filled if the test time is equal to or greater than the threshold time.