Shrink-induced sorting using integrated nanoscale magnetic traps

Abstract

We present a plastic microfluidic device with integrated nanoscale magnetic traps (NSMTs) that separates magnetic from non-magnetic beads with high purity and throughput, and unprecedented enrichments. Numerical simulations indicate significantly higher localized magnetic field gradients than previously reported. We demonstrated >20 000-fold enrichment for 0.001% magnetic bead mixtures. Since we achieve high purity at all flow-rates tested, this is a robust, rapid, portable, and simple solution to sort target species from small volumes amenable for pointof-care applications. We used the NSMT in a 96 well format to extract DNA from small sample volumes for quantitative polymerase chain reaction (qPCR). V C 2013 American Institute of Physics.

Enhanced emission of fluorophores on shrink-induced wrinkled composite structures

“…This is important to achieve large fluorescence enhancements in other regions of the excitation wavelength spectrum. We have also recently demonstrated that our Ni structures can generate strong localized magnetic gradients to serve as effective nanotraps for capture and separation [42]. Combining this utility with the large signal enhancements demonstrated here can pave the way to create a comprehensive integrated device to readily magnetically trap and sensitively detect labeled molecules and nanoparticles.…”

“…Recently, we demonstrated that with a very thin layer of Ni, effective ferro-magnetic nanotraps that localize strong magnetic fields can be formed with these wrinkles [42]. We found that increasing the Ni thickness to 30 nm increased the size and reduced the sharpness of the nanowrinkles and as a result decreased the magnetic strength.…”

“…Moreover, such wrinkle structures have been extensively characterized and leveraged for various applications [40–42, 44, 47–54]. Recent work has even shown that the wrinkles can be somewhat deterministic [47].…”

Microchip-based detection of magnetically labeled cancer biomarkers

“…Obviating photolithography enables devices to be fabricated that are larger, three-dimensional, inexpensive, and more practical for clinical use [36–38]. One recent device used three-dimensional columns of self-assembled super-paramagnetic beads that reach into a microfluidic channel to create an efficient sorting structure [37].…”

Inkjet-Print Micromagnet Array on Glass Slides for Immunomagnetic Enrichment of Circulating Tumor Cells

“…A shrink induced magnetic trap is formed on a shape memory polymer and integrated into a microfluidic device to extract DNA samples for qPCR studies [7]. Imprinting technology is used to pattern magnetic microparticles on polymer substrates using a magnetic grid as the template.…”