Acoustic Droplet Ejection for Single Cell Retrieval
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Solution Overview
Problem
Current methods for single cell analysis are limited by low throughput, labor intensity, and inability to integrate automation for isolation, screening, and retrieval of cells or biomolecules, particularly in digital PCR platforms that lack the capability for downstream processing of positive samples.
Innovation Solution
An automated high-throughput method using a microfluidic chip with microwell arrays and an external acoustic transducer for spatial isolation and image-based screening of single cells or biomolecules, enabling retrieval of selected cells or biomolecules for downstream processing, including digital PCR amplification products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If droplet based microfluidics is used for high throughput single cell isolation, then automation and high throughput are achieved, but sequential reagent addition after encapsulation becomes impossible
Solution Approach 1:
The device segments the microfluidic system into distinct functional zones: a first microfluidic chamber for cell encapsulation in droplets, and a second microfluidic chamber for sequential reagent addition. This spatial segmentation allows droplets to be formed and then transported to a separate location where reagents can be added sequentially without disrupting the encapsulation process
Solution Approach 2:
A bridge channel serves as an intermediary pathway connecting the first microfluidic chamber (encapsulation zone) to the second microfluidic chamber (reagent addition zone). This intermediary structure enables the transfer of encapsulated droplets while maintaining the integrity of both functional zones and allowing independent operation of each chamber
2Ease of manufacture
If microwell array platforms are used for single cell isolation, then isolation is achieved, but manual reagent addition and micropipette retrieval are required
Solution Approach 1:
The invention replaces manual micropipette operations with an automated acoustic droplet ejection system. Acoustic waves are used to non-contactly eject droplets from microwells for retrieval, eliminating the need for physical micropipette manipulation and enabling full automation of the retrieval process
Solution Approach 2:
The system uses acoustic waves (a form of mechanical energy propagation through fluid) to manipulate droplets within the microfluidic chip. The acoustic field enables contactless manipulation, ejection, and retrieval of droplets containing single cells or biomolecules, replacing traditional mechanical pipetting methods
3Productivity
If flow cytometry is used for high throughput sorting, then high throughput is achieved, but single time point analysis and large downstream volumes are required
Solution Approach 1:
The invention transitions from the continuous flow dimension of flow cytometry to a spatial array dimension with thousands of individually addressable microwells. This dimensional change allows parallel processing of many samples simultaneously while maintaining minimal downstream volumes, as each microwell contains a discrete, small volume that can be independently manipulated and retrieved
4Measurement precision
If digital PCR is performed in microwells, then precision and sensitivity are improved, but integrated retrieval capability for downstream processing is lacking
Solution Approach 1:
The microfluidic device integrates multiple functions into a single platform: cell encapsulation, digital PCR amplification, fluorescent detection, and acoustic ejection for downstream processing. This multi-functional design allows the same micrawell array to serve both as the reaction chamber for precise digital PCR and as a source for retrieving positive samples for further analysis
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 the detection and retrieval of rare cells and digital PCR products for next-generation sequencing, improving throughput and efficiency in single cell analysis and processing.
Implementation Method 1
an acoustic transducer configured to apply an acoustic beam to the microfluidic chip
Data Source
AI summary
Described here is a device comprising a microfluidic chip and an acoustic transducer external to the microfluidic chip, wherein the microfluidic chip comprises a channel in communication with a microwell having a volume less than one microliter, and wherein the acoustic transducer is coupled to the microfluidic chip via a coupling medium. Also described here is a method for analyzing a cell or a biomolecule, comprising applying a focused acoustic beam to a microfluidic chip comprising a channel in fluid communication with a microwell having a volume less than one microliter, wherein the microwell comprises an aqueous compartment comprising a cell or a biomolecule, wherein the channel comprises a non-aqueous liquid phase immiscible with the aqueous compartment which encapsulates the aqueous compartment in the microwell, and wherein the acoustic beam displaces a meniscus at an interface of the aqueous compartment and the non-aqueous liquid phase thereby ejecting the aqueous compartment from the microwell into the channel as an aqueous droplet.