Encoding Microreactors with Droplet Chains in Microfluidics

Abstract

Droplet-based high throughput biomolecular screening and combinatorial synthesis entail a viable indexing strategy to be developed for the identification of each microreactor. Here, we propose a novel indexing scheme based on the generation of droplet sequences on demand to form unique encoding droplet chains in fluidic networks. These codes are represented by multiunit and multilevel droplets packages, with each code unit possessing several distinct signal levels, potentially allowing large encoding capacity. For proof of concept, we use magnetic nanoparticles as the encoding material and a giant magnetoresistance (GMR) sensor-based active sorting system supplemented with an optical detector to generate and decode the sequence of one exemplar sample droplet reactor and a 4-unit quaternary magnetic code. The indexing capacity offered by 4-unit multilevel codes with this indexing strategy is estimated to exceed 10, which holds great promise for large-scale droplet-based screening and synthesis.

Real-Time Tracking of Individual Droplets in Multiphase Microfluidics

“…Downstream of the verification sensor, a GMR sensor, the droplets were further polymerized using a standard alginate and Ca 2+ polymerization reaction to maintain their code for long time storage. Finally, to tackle the challenge of decoding, code spacing and interpretation, Wong et al developed a complementary system allowing precise determination of the code generation, code starting point via introduction of a fluorescent marker droplet at each code beginning and a final readout (Figure 9c) [85]. In the spirit of ultra-sensitive highthroughput detection in micro-and millifluidics, state-of-the-art biosensors based on micro-and nanomaterials lead inevitably to big amounts of data points.…”

Two Orders of Magnitude Boost in the Detection Limit of Droplet-Based Micro-Magnetofluidics with Planar Hall Effect Sensors

“… 47 , 48 Novel high-capacity indexing schemes were put forth based on multiphase microfluidic networks for large-scale screening applications. 47 , 48 These features are crucial to address the needs of modern medical research, e.g., drug discovery. 49 …”

“…47,48 Novel high-capacity indexing schemes were put forth based on multiphase microfluidic networks for large-scale screening applications. 47,48 These features are crucial to address the needs of modern medical research, e.g., drug discovery. 49 For these applications, high-performance magnetic field sensors have to be integrated in microfluidic geometries to enable real-time tracking of low concentrations of magnetic species in droplets as they flow by the sensor.…”

“…During the last decades, the combination of magnetism, micro-magnetofluidics, and microfluidics gained major interest due to its potential for novel functionalities in lab-on-a-chip approaches like sensing and actuating. , In this regard, droplet-based micro-magnetofluidics, also known as continuous-flow micro-magnetofluidics, emerged as a novel analytic tool encompassing integrated novel functionalities, e.g., analytics in a flow cytometry format, − magnetic barcoding, and sorting of magnetically encoded emulsion droplets. , Novel high-capacity indexing schemes were put forth based on multiphase microfluidic networks for large-scale screening applications. , These features are crucial to address the needs of modern medical research, e.g., drug discovery …”

Contactless mass transfer for intra-droplet extraction

“…Such droplet sorting at the outlet had been noted a decade ago 21 . However, there are few reports that practically demonstrate droplet sorting to designated outlets 22 . In this study, we show the concept of intra-slug material transfer and a simple system for the detection and sorting of slugs at the milli-reactor outlet.…”