Sealed Microwell Assay Bead Geometry
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Solution Overview
Problem
Microwell-based assays for single cell analysis face issues such as cross-contamination, dilution of biomolecules, and variability in bead-cell pairing, leading to compromised accuracy and efficiency.
Innovation Solution
A novel geometric pairing of microwells and beads, where the bead width is greater than the microwell bottom width, forming a sealed analytical space that prevents cross-contamination and reduces the sample volume, ensuring consistent bead-cell proximity and high ligand binding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If microwells are left unsealed to simplify the assay procedure, then the device complexity is reduced, but cross-contamination occurs between microwells compromising analysis accuracy
Solution Approach 1:
The bead itself performs the sealing function by forming an interface with the microwell wall, eliminating the need for separate sealing components or steps. The bead's geometry and positioning automatically create the seal that prevents cross-contamination while maintaining assay simplicity.
Solution Approach 2:
The bead serves multiple functions simultaneously: it acts as a carrier for ligands, a physical seal to prevent cross-contamination, and a positioning element for consistent cell-bead proximity. This multi-functionality resolves the contradiction by achieving sealing without adding device complexity.
2Device complexity
If a large volume of medium is used to accommodate both cell and bead in microwell, then the microwell configuration is simpler, but biomolecule concentration decreases due to dilution reducing binding efficiency
Solution Approach 1:
The bead acts as an intermediary that defines the functional reaction volume. By positioning the bead to contact the micrawell wall and creating a sealed space, the effective volume for biomolecule interaction is reduced to the region between the bead and micrawell bottom, increasing concentration without requiring complex volume control mechanisms.
3Ease of operation
If bead and cell are placed next to each other on micrawell bottom to simplify loading, then the ease of operation is improved, but pairing variability increases leading to inconsistent binding efficiency
Solution Approach 1:
The micrawell employs an asymmetric geometry where the bottom has a smaller diameter than the opening. This asymmetric design naturally guides the bead to a specific position where it contacts the micrawell wall, creating a consistent geometric relationship between bead and cell that ensures uniform pairing across all micrawells while maintaining simple loading procedures.
4Reliability
If bead width is made greater than micrawell bottom width to form sealed space, then cross-contamination is prevented and binding efficiency increases, but the difficulty of detecting and measuring increases
Solution Approach 1:
The sealing mechanism transitions from a two-dimensional planar seal to a three-dimensional geometric seal formed by the bead's curvature contacting the micrawell wall. This dimensional change creates an effective seal that prevents cross-contamination while maintaining optical transparency for detection, as the seal is formed by the bead's position rather than an opaque barrier.
Data Source
AI summary
The present invention provides methods, systems and kits for performing microwell analysis in sealed small volumes. The microwells of the invention are sealed through the pairing of microwell and bead geometry wherein the diameter of the beads is greater than the diameter of the bottom of the microwells. Loading the beads into the microwells seals samples within an analytical space between the bottom of a nested bead and the bottom of the subject microwell.