Magnetofluidic platform for multidimensional magnetic and optical barcoding of droplets

Abstract

We present a concept of multidimensional magnetic and optical barcoding of droplets based on a magnetofluidic platform. The platform comprises multiple functional areas, such as an encoding area, an encoded droplet pool and a magnetic decoding area with integrated giant magnetoresistive (GMR) sensors. To prove this concept, penicillin functionalized with fluorescent dyes is coencapsulated with magnetic nanoparticles into droplets. While fluorescent dyes are used as conventional optical barcodes which are decoded with an optical decoding setup, an additional dimensionality of barcodes is created by using magnetic nanoparticles as magnetic barcodes for individual droplets and integrated micro-patterned GMR sensors as the corresponding magnetic decoding devices. The strategy of incorporating a magnetic encoding scheme provides a dynamic range of ~40 dB in addition to that of the optical method. When combined with magnetic barcodes, the encoding capacity can be increased by more than 1 order of magnitude compared with using only optical barcodes, that is, the magnetic platform provides more than 10 unique magnetic codes in addition to each optical barcode. Besides being a unique magnetic functional element for droplet microfluidics, the platform is capable of on-demand facile magnetic encoding and real-time decoding of droplets which paves the way for the development of novel non-optical encoding schemes for highly multiplexed droplet-based biological assays.

Magnetic Suspension Array Technology: Controlled Synthesis and Screening in Microfluidic Networks

“…These produced magnetic alginate droplets are detected by the sensor‐1, as the real‐time data are featured with isolated detection peaks ( Figure a). Hence, the scattered signal amplitude reflects a deviation in the distribution of encapsulated magnetic particles while the varied median/mean values of the scattered plots evidence the variations of the dominant concentrations of encapsulated magnetic content produced by different flow parameters (Figure b). This provides information on the magnetic properties and their distribution in a batch.…”

Encoding Microreactors with Droplet Chains in Microfluidics

“…The time scale of indexing with the current system is limited by the frequency of elementary droplet bits produced from upstream and the switching rate of electromagnetic valves (about 25 ms) used to isolate the droplets. The time scale could be improved by producing the elementary droplets initially at a high rate (> 100 Hz), 19 which potentially allows to reduce the time scale for generating a 4-unit droplet code below 1 s.…”

Discovery in Droplets

“…79 However, the spectral resolution of fluorescent dyes as well as the sensitivity and dynamic range of the decoding optics limit the number of possible barcodes << 10 5 . A magnetic nanoparticle encoding strategy coupled to optical encoding increased coding capacity 10-fold, 80 suggesting that multiplexing numerous orthogonal coding systems is a viable option moving forward. Likewise, a route to DNA-encoded combinatorial solid-phase libraries 81 is compatible with bead screening in droplets (Figure 10).…”