Microfluidic Surface Dried Reagent Volume-Free Addition
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Solution Overview
Problem
Microscale assays face challenges in volume-free reagent addition and solution exchange due to significant volume perturbations and dilution issues, which are not effectively addressed by traditional macro-scale methods.
Innovation Solution
A microfluidic device with a surface configured to repel aqueous solutions, using dried reagents that are re-dissolved by droplets of aqueous solutions, and employing paramagnetic beads manipulated by magnetic forces to perform volume-free reagent addition and exclusion-based sample preparation without significant volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reagent is added to microscale droplet, then reagent is incorporated into the assay, but the total volume of the droplet increases significantly causing dilution of original solution
Solution Approach 1:
The reagent is dried onto the surface before the assay begins. This preliminary action allows the reagent to be present in a concentrated, space-efficient form that can be incorporated into the microscale droplet without adding significant volume, thereby avoiding dilution of the original solution while still achieving complete reagent incorporation.
Solution Approach 2:
The reagent undergoes a parameter change from liquid to dried solid form. This phase change enables the reagent to occupy minimal volume on the surface, allowing it to be added to microscale droplets without significantly increasing the total volume and causing dilution, while still maintaining full functional concentration when rehydrated.
2Adaptability or versatility
If solution exchange is performed in microscale assays, then solution conditions can be changed, but residual liquid on solid surface becomes significant due to high surface to volume ratio
Solution Approach 1:
The method extracts the liquid phase from the assay by using dried reagents on the surface. Instead of exchanging liquid solutions that would leave residual volumes, the reagent is presented in a dried state that can be directly incorporated without liquid exchange, thereby eliminating the residual liquid problem while maintaining the ability to change solution conditions through controlled rehydration.
3Ease of operation
If traditional macro-scale liquid handling is used, then reagent addition is reliable and easy, but it becomes impossible or unreliable for microscale assays with very small liquid volumes
Solution Approach 1:
The method replaces traditional mechanical liquid handling systems (pipettes, syringes) with a surface-based reagent delivery system. Dried reagents on the surface are incorporated through controlled droplet placement and capillary action, eliminating the need for precise mechanical liquid manipulation while achieving reliable and reproducible reagent addition in microscale assays.
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 precise, non-dilutive, and efficient reagent addition and sample preparation in microscale assays, minimizing analyte loss and preserving molecular interactions, suitable for multi-step assays like DNA extraction and antimicrobial susceptibility testing.
Implementation Method 1
The droplet picks-up and re-dissolves the dried reagent therein so as to expose the portion of the surface
Implementation Method 2
The step of positioning the droplet of the aqueous solution on the dried reagent may include the steps of generating a magnetic force and positioning the magnetic force to interact magnetically with the paramagnetic beads within the droplet
Implementation Method 3
a microfluidic device including a reservoir defined by a surface configured to repel an aqueous solution
Implementation Method 4
The step of providing the dried reagent on the portion of the surface includes the additional steps depositing the reagent on the surface and allowing reagent to dry and physically adsorb onto surface
Data Source
AI summary
A method of sample preparation for streamlined multi-step assays is provided. The method includes the step of providing a microfluidic device including a reservoir defined by a surface configured to repel an aqueous solution. A dried reagent is provided on a portion of the surface and the reservoir is filled with an oil. A first droplet formed from the aqueous solution is positioned on the dried reagent so to pick-up and re-dissolve the dried reagent therein so as to expose the portion of the surface. In addition, a second droplet of an aqueous solution may be deposited on a hydrophilic spot patterned on the surface. A magnetic force may be configured to interact magnetically with the paramagnetic beads within the first droplet to move the droplet through the oil in the reservoir or to move the paramagnetic beads from the first droplet, through the oil, into the second droplet.