The escalating research interests in porous media microfluidics, such as microfluidic paper-based analytical devices (μPADs), have fostered a new spectrum of microfluidic devices for point-of-care diagnosis and biosensing. In this paper, we report diatomite microfluidic devices, which consist of multi-scale hierarchically porous photonic crystal biosilica channels, as an innovative lab-on-a-chip platform to detect hazardous chemicals. The diatomite microfluidic devices in this work are fabricated by simple spin-coating and tape-stripping diatomaceous earth on regular glass slides with cross section of 400×30μm2. As the most unique feature, our diatomite microfluidic devices can simultaneously perform on-chip chromatography to separate small molecules from complex samples and acquire the surface-enhanced Raman scattering spectra of the target chemicals with high specificity. Owing to the ultra-small dimension of the diatomite microfluidic channels and the photonic crystal effect from the fossilized diatom frustules, we demonstrate unprecedented sensitivity down to ppb-level when detecting pyrene (1ppb) from mixed sample with Raman dye and cocaine (10ppb) from human plasma. This pioneering work proves the exclusive advantage of diatomite microfluidic devices as emerging microfluidic devices for chemical and biomedical sensing.
Xianming Kong, Kenneth Squire, Xinyuan Chong, and Alan X. Wang, "Ultra-sensitive diatomite microfluidic devices for hazardous chemical sensing (Conference Presentation)," Proc. SPIE 10491, Microfluidics, BioMEMS, and Medical Microsystems XVI, 104910E (Presented at SPIE BiOS: January 28, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2292291.5751458226001.
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