Capacitive Proximity Sensing for Fluid Transfer Probe Tip Detection
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Solution Overview
Problem
Automated fluid transfer systems in diagnostic analyzers face challenges in accurately detecting fluid levels and confirming the presence or absence of protective tips on fluid transfer probes, particularly due to the complexity and vulnerability of optical detectors used in existing systems.
Innovation Solution
A capacitive proximity sensing system is employed to detect fluid levels and confirm the presence or absence of protective tips on fluid transfer probes, utilizing a capacitive voltage divider and magnetic separation wash stations to ensure accurate and reliable fluid transfer operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical detectors are used to detect the presence or absence of protective tips and fluid levels, then detection capability is provided, but device complexity increases and reliability decreases due to vulnerability to dust and spillage
Solution Approach 1:
The patent replaces optical detection systems with capacitive sensing technology. The capacitive sensor detects changes in capacitance caused by the presence or absence of protective tips and fluid levels, eliminating the need for optical components such as emitters and detectors that are vulnerable to dust and spillage. This substitution of mechanical/electrical sensing for optical sensing resolves the contradiction by improving reliability while reducing device complexity.
Solution Approach 2:
The patent changes the detection parameter from optical properties (light transmission/blockage) to electrical properties (capacitance). By measuring capacitance changes in the fluid transfer probe assembly, the system can detect tip presence and fluid levels without using vulnerable optical components. This parameter change enables more reliable detection with simpler hardware.
2Reliability
If optical detectors are used for tip detection, then presence confirmation is achieved, but the system becomes vulnerable to performance degradation from dust and spillage
Solution Approach 1:
The patent substitutes capacitive sensing for optical detection, replacing light-based measurement with electrical field-based measurement. The capacitive sensor measures changes in electrical capacitance caused by the dielectric properties of the protective tip and fluid, making the detection immune to dust and spillage that plague optical systems. This resolves the contradiction by eliminating susceptibility to environmental contaminants.
Solution Approach 2:
The patent uses the electrical field as an intermediary between the sensor and the target objects (protective tips and fluid). The capacitive sensor detects changes in the electrical field caused by the presence of these objects, without requiring direct line-of-sight or physical contact. This intermediary approach makes the detection process robust against dust and spillage that would interfere with optical paths.
3Measurement precision
If capacitive proximity sensing is used to detect fluid levels and tip presence, then measurement precision is improved and system vulnerability is reduced, but additional sensing components are required
Solution Approach 1:
The patent makes the fluid transfer probe assembly itself serve dual functions: both fluid transfer and capacitive sensing. The probe's conductive structure acts as both the fluid transfer conduit and the capacitive sensor, eliminating the need for separate sensing components. This multi-functionality achieves precise measurement of fluid levels and tip presence without adding device complexity.
Solution Approach 2:
The patent enables the fluid transfer probe to sense its own state (presence of protective tip, fluid level) through capacitive measurements taken during normal operation. The probe's own electrical characteristics are used to detect its operational state, eliminating the need for external sensing components. This self-service approach improves measurement precision without 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
The capacitive sensing system provides precise detection of fluid levels and tip presence, reducing the risk of cross-contamination and improving the accuracy of fluid transfer processes in automated analyzers, while simplifying the system and reducing the vulnerability to environmental factors.
Implementation Method 1
capacitive level sensing systems... When the probe contacts a fluid level surface within the receptacle, a measurable change of the capacitance occurs, so that contact with the fluid level surface can be detected
Implementation Method 2
the optical detector may comprise an emitter component and a detector component, and the fluid transfer probe can be moved into the optical path so as to place the protective tip between the emitter component and the detector component. If the tip is present, the optical path is blocked
Data Source
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AI summary
A fluid transfer apparatus includes a fluid transfer probe, a fluid level detection system, and a tip detection system. The fluid level detection system is configured to detect contact by the fluid transfer probe with a fluid surface within a receptacle from a signal based on the capacitance of the fluid transfer probe. The tip detection system is configured to detect the presence or absence of a tip at a distal end of the fluid transfer probe from a signal based on the capacitance of the fluid transfer probe.