Pipette Stirring via Dynamic Tip Positioning
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Solution Overview
Problem
Existing stirring methods for specimens in detection apparatuses, such as those using pipettes, fail to achieve satisfactory stirring, especially when the specimen volume and pipette tip volume differ significantly, leading to inaccurate analyte detection due to air incorporation and uneven concentration distributions.
Innovation Solution
A detection apparatus and method that employs a pipette with a detachable tip, a moving section, and a control system to stir the specimen by drawing and discharging it within the container, ensuring effective mixing by positioning the pipette tip at specific locations to prevent air incorporation and maintain uniform concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pipette with large volume is used to stir a small amount of specimen, then stirring effect is improved, but air bubbles are incorporated and apparatus size increases
Solution Approach 1:
The pipette tip position is dynamically adjusted between two states: positioned at the bottom of the container during specimen drawing to maximize stirring effect, and positioned above the liquid surface during discharge to prevent air bubble incorporation. This dynamic positioning resolves the contradiction between achieving good stirring and avoiding air bubbles.
Solution Approach 2:
The stirring process is segmented into two distinct phases: drawing phase where the pipette tip is at the bottom for effective mixing, and discharge phase where the pipette tip is elevated to avoid air incorporation. This segmentation allows each phase to optimize for its specific function without compromising the other.
2Reliability
If the leading end of the pipette tip is fixed near the bottom surface during drawing and discharging, then stirring effect is improved, but air bubbles are incorporated during discharging
Solution Approach 1:
The system dynamically changes the pipette tip position based on the operation phase: at the bottom during drawing for stirring, and elevated during discharge to prevent air bubble incorporation that would affect quantitative accuracy. This resolves the contradiction between stirring effectiveness and measurement precision.
3Stability of the object's composition
If blood cells are allowed to precipitate before detection, then settling occurs, but hematocrit fluctuates and analyte detection accuracy decreases
Solution Approach 1:
The system performs periodic stirring by repeatedly drawing and discharging the specimen at controlled time intervals before detection. This periodic action prevents blood cell precipitation and maintains stable hematocrit levels, ensuring accurate analyte detection throughout the detection window.
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 allows for accurate detection of analytes by ensuring thorough stirring and uniform concentration distribution, even with varying specimen and pipette tip volumes, thereby improving the quantitative performance of specimen collection.
Implementation Method 1
These methods exploit the phenomenon of surface plasmon resonance (SPR) occurring upon irradiation of a metal film with light under predetermined conditions
Implementation Method 2
when the metal film is irradiated with excitation light, the fluorophore that labels the analyte is excited with SPR-enhanced electric fields, thereby emitting fluorescence
Data Source
AI summary
A detection device for detecting a substance to be detected contained in a specimen has a pipette that has a detachable pipette tip and that suctions or discharges a specimen in a container, a pipette-moving unit for moving the pipette, and a control unit for controlling the pipette and pipette-moving unit. The control unit controls the pipette and the pipette-moving unit so that the pipette suctions a portion of specimen in the container with the pipette-moving unit having moved the distal end of the pipette tip to a position (a) in the lower side of the container, and thereafter discharges in the container the specimen suctioned by the pipette to stir the specimen with the pipette-moving unit having moved the distal end of the pipette tip to a position (b) above the position (a).