Flattened Droplet Single Cell Detection via Overlay Liquid
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Solution Overview
Problem
Traditional microtiter plates face challenges in reliably detecting single cells due to the 'edge-effect' caused by solid walls, which interferes with optical measurements and requires additional processing steps like spinning and fluorescent labeling, making the process time-consuming and complex.
Innovation Solution
A method and apparatus that form a test body of liquid on a substrate with a contact angle lower than the equilibrium contact angle, allowing for optical imaging to determine the presence of a single cell quickly and reliably, by flattening the droplet shape to reduce curvature and facilitate faster cell settlement, and optionally overlaying with an immiscible liquid to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional microtiter plates are used for single cell detection, then cells can be cultured in standardized wells, but optical measurements are interfered with by edge-effects from solid walls
Solution Approach 1:
The patent introduces an overlay liquid (immiscible with the test liquid) as an intermediary layer between the curved upper interface of the test body and the imaging system. This overlay liquid with refractive index closer to that of the test body reduces refraction at the interface, eliminating edge-effects and enabling reliable optical detection of single cells throughout the entire test body including regions near the boundaries.
Solution Approach 2:
The patent changes the refractive index parameter of the imaging environment by introducing an overlay liquid with a specific refractive index (e.g., 1.46) that is closer to the test body's refractive index (e.g., 1.33) than air's refractive index (1.00). This parameter change reduces light refraction at the curved interface, eliminating edge-effects and improving measurement reliability.
2Object-affected harmful factors
If cells are deposited in small drops to avoid edge-effects, then optical detection is improved, but image quality is reduced by curvature at the upper interface
Solution Approach 1:
The overlay liquid acts as an optical intermediary that matches the refractive index of the test body more closely than air does. This reduces refraction at the curved upper interface, eliminating dark regions and improving image quality across the entire field of view including edge regions, while maintaining the benefit of avoiding solid wall edge-effects.
3Stability of the object's composition
If traditional equilibrium droplets are used, then liquid stability is maintained, but cell settlement time is increased and detection is delayed
Solution Approach 1:
The patent changes the contact angle parameter from the equilibrium value to a lower value, creating a flattened test body with reduced height. This parameter change reduces the distance cells must travel to settle on the substrate, decreasing settlement time from minutes to seconds, while the overlay liquid provides sufficient structural stability for imaging.
Solution Approach 2:
The patent performs preliminary flattening of the test body before cell deposition by creating a test body with contact angle lower than equilibrium. This preliminary action reduces the height and prepares the system for rapid cell settlement, allowing cells to reach the substrate quickly and enabling immediate imaging without waiting for prolonged settlement periods.
4Speed
If contact angle is reduced to flatten the droplet, then cell settlement speed is improved, but droplet shape control becomes more difficult
Solution Approach 1:
The overlay liquid serves as a mediator that allows the system to achieve flattened droplet shapes with low contact angles while maintaining sufficient structural integrity. The overlay liquid provides external support that compensates for the reduced internal stability from the flattened shape, making the process easier to control and reproduce.
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 reliable and efficient detection of single cells with reduced processing time and complexity, avoiding the edge-effect and enabling high-quality optical imaging without the need for expensive equipment.
Implementation Method 1
forming on a substrate surface a test body of liquid, wherein a contact angle between the test body of liquid and the substrate surface is lower than an equilibrium contact angle
Implementation Method 2
light is made to pass through the drops and is then imaged
Implementation Method 3
reduces the time required for a cell to settle onto the substrate surface
Data Source
AI summary
Methods and apparatus for providing an isolated single cell are provided. In one disclosed arrangement, a test body of liquid is formed on a substrate surface. A contact angle between the test body of liquid and the substrate surface is lower than an equilibrium contact angle. An optical image of the test body of liquid is analysed to determine whether one and only one cell is present in the test body of liquid.