Editors' ChoiceBioengineering

Extra! Extra! Microfluidic chips go to print

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Science Translational Medicine  04 May 2016:
Vol. 8, Issue 337, pp. 337ec72
DOI: 10.1126/scitranslmed.aaf8774

Roll-to-roll (R2R) manufacturing involves continuous processing of substrates transferred between two moving rolls of material—a printing technique common to the newspaper industry. Because of its mass production capability, R2R processing is also considered a promising technology for printed electronics. With that in mind, Wang et al. applied R2R printing to develop low-cost and disposable thermoplastic microfluidic chips to sort microparticles. The authors wanted to use inertial focusing to precisely position their particles and manipulate them in microfluidic flow. Until now, inertial sorting devices comprised microchannels with heights (h) greater than widths (w). R2R chip fabrication, however, is limited to microchannels with w > h. Wang et al. devised a microfluidic device design that was compatible with R2R fabrication and allowed for inertial focusing that could separate even 10-µm from 15-µm particles in such a low-aspect-ratio straight channel. Using variously sized synthetic beads and bovine white blood cells to characterize their device, the researchers achieved continuous size-based sorting with high purity, as well as separation efficiencies of 97 to 99% at constant flow rates. A key strength of their approach lies in the ability to simply modify the input flow rate to fine-tune the cut-off size for particle sorting. This obviates the need to redesign and manufacture additional devices to accommodate particles with different size distributions. A perhaps underappreciated feature of their fluidic device is its reliable sealing through solvent-based bonding. Making closed fluidic devices with thermoplastics represents a major challenge for most fast-fabrication methods, including R2R.

Despite preclinical promise, the surface roughness and plastic properties of the microchannels could reduce performance with clinical samples. Tapping into surface chemistry engineering principles to enhance coating could help efficiency and purity. Moreover, further integration with printed electronics and sensing components (e.g., impedance sensors) could enhance the breadth and depth of downstream analyses. The study reflects how inspiration from seemingly disparate industries can propel translational efforts. And that’s news fit to print.

X. Wang et al., A disposable, roll-to-roll hot-embossed inertial microfluidic device for size-based sorting of microbeads and cells. Lab Chip 10.1039/C6LC00215C (2016). [Abstract]

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