Dosing Device Liquid Level Detection Using Inductive Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dosing devices in laboratory settings face challenges in accurately determining the liquid level without specialized cannulas or aspirator tips, leading to increased costs and cleaning issues due to immersion of optical components in liquids.
Innovation Solution
A method and dosing device that uses a cannula with an optical sensor between the cannula and sampling container to measure optical parameters of aspirated fluid, allowing for precise determination of liquid level without specialized cannulas, and avoiding immersion of sensors in liquids, using a control unit to calculate the cannula's position based on speed, volumetric flow, and cannula volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cannula is moved deeper into the liquid to ensure proper immersion, then the liquid level detection is more reliable, but liquid remains attached to the outer wall of the cannula and may drip off, distorting the dosed volume or contaminating other liquids
Solution Approach 1:
The patent replaces capacitive or optical sensors that require direct contact with the liquid with an inductive sensor that detects the liquid level through non-contact means. The inductive sensor detects changes in inductance caused by the proximity of the liquid to the cannula tip without requiring the sensor itself to be immersed, thus avoiding liquid attachment and contamination while maintaining reliable detection.
2Measurement precision
If capacitive measurement is used to detect liquid immersion, then the filling level can be determined, but the liquid must be conductive for the measurement to work
Solution Approach 1:
The patent substitutes capacitive sensing with inductive sensing. The inductive sensor generates an electromagnetic field that interacts with the liquid regardless of its electrical conductivity properties. This allows the system to detect liquid levels in both conductive and non-conductive liquids, significantly expanding the versatility of the dosing device while maintaining precise measurement capability.
3Measurement precision
If optical systems with fiber-optic sensors are integrated into the cannula, then phase transitions can be detected, but special cannulas are required which greatly increases operating costs
Solution Approach 1:
The patent extracts the sensor from the cannula structure itself and positions it externally near the cannula tip. The inductive sensor is mounted on the dosing device body rather than being integrated into the cannula, allowing the use of standard, inexpensive cannulas while maintaining the ability to detect liquid levels and phase transitions through electromagnetic field interactions.
Solution Approach 2:
The patent uses the electromagnetic field as an intermediary between the sensor and the liquid. Instead of requiring direct contact between the sensor and liquid (which would necessitate specialized cannulas), the electromagnetic field mediates the detection process, allowing standard cannulas to be used while still achieving precise liquid level and phase transition detection.
4Measurement precision
If optical components are immersed in the liquid for detection, then liquid level can be measured, but cleaning becomes problematic
Solution Approach 1:
The patent replaces optical components that require immersion with an inductive sensor that operates through non-contact electromagnetic field detection. The sensor remains outside the liquid, eliminating the need for cleaning while maintaining accurate liquid level measurement capability.
Solution Approach 2:
The patent extracts the detection function from the liquid environment by positioning the inductive sensor externally. The sensor is taken out of the liquid and instead detects liquid level through electromagnetic field interactions, thereby eliminating contamination and cleaning requirements while preserving measurement precision.
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
Enables accurate liquid level determination in laboratory vessels without the need for special cannulas or complex cleaning, using standard cannulas and minimizing sensor exposure to liquids, thus reducing costs and improving operational efficiency.
Implementation Method 1
At least one optical sensor measures at least one optical parameter of the aspirated fluid, wherein the at least one sensor is arranged between the cannula and the sampling container
Data Source
AI summary
A method for operating a dosing device comprising a control unit, a dosing unit with a cannula of a first volume, and a sampling container connected to the cannula. The method comprises moving the dosing unit in a first direction along an axis to move the cannula into a vessel containing a liquid; constantly aspirating fluid through the cannula with a predetermined volumetric flow; measuring at least one optical parameter of the aspirated fluid; when a change of the optical parameter is detected, storing a first position of the dosing unit on the axis and interrupting the movement of the dosing unit; and calculating a second position of the dosing unit on the axis at which the tip of the cannula has penetrated a first phase boundary upon immersion into the liquid. The calculation is performed on the basis of the first position, the predetermined speed, the first volume and the predetermined volumetric flow.