Continuous-Flow Chemical Processing on a Microchip by Combining Microunit Operations and a Multiphase Flow Network

Abstract

A new design and construction methodology for integration of complicated chemical processing on a microchip was proposed. This methodology, continuous-flow chemical processing (CFCP), is based on a combination of microunit operations (MUOs) and a multiphase flow network. Chemical operations in microchannels, such as mixing, reaction, and extraction, were classified into several MUOs. The complete procedure for Co(II) wet analysis, including a chelating reaction, solvent extraction, and purification was decomposed into MUOs and reconstructed as CFCP on a microchip. Chemical reaction and molecular transport were realized in and between continuous liquid flows in a multiphase flow network, such as aqueous/aqueous, aqueous/organic, and aqueous/organic/aqueous flows. When the determination of Co(II) in an admixture of Cu(II) was carried out using this methodology, the determination limit (2sigma) was obtained as 18 nM, and the absolute amount of Co chelates detected was 0.13 zmol, that is, 78 chelates. The sample analysis time was faster than that of a conventional processing system. Moreover, troublesome operations such as phase separation and acid and alkali washing, all necessary for the conventional system, were simplified. The CFCP methodology proposed here can be applied to various on-chip applications.

Microfluidic transport based on direct electrowetting

“…Unlike the previous studies which use a droplet, we transported a liquid continuously from an injection port, because it is a common approach currently used in microfluidic systems. 14,15 Although current generation caused by redox reactions on the electrode surface might be considered a disadvantage, the much lower operating voltage in the absence of a dielectric layer provides a realistic altera͒ Author to whom all correspondence should be addressed; electronic mail: hsuzuki@ims.tsukuba.ac.jp native for the future generation lab-on-a-chip devices. When the end of a hydrophilic capillary or planar plates with a narrow gap is immersed in an aqueous solution, the solution rises.…”

Comparison of Performance Parameters of Photothermal Procedures in Homogeneous and Heterogeneous Systems

“…(3), are at the same level for aqueous, organo-aqueous, and organo-aqueous extraction systems: the average normalized LOD of the latter is only 20% lower than that of the former. This shows that an actual increase in the sensitivity of extraction procedures results from high εTL and high excitation powers in these studies, [25][26][27][28][29][30][31][32][33][34] and not from the solvent properties. On the contrary, the normalized LODs for organo-aqueous mixtures exhibit the same LOD decrease as do the extraction procedures, but with much less changes in methodology compared to aqueous solutions.…”

“…We have chosen Co and Fe determination because (i) the photometric methods for these metals are both sensitive and reliable; 24 (ii) they are based on the same reaction type, chelation; (iii) these methods cover all of the selected procedure types; and (iv) optimized TLS/TLM procedures have low practical LODs under batch and flow conditions. 3,4,[25][26][27][28][29][30][31][32][33][34][35][36] A total of 39 procedures (16 for Fe and 23 for Co) were considered.…”

Integration of Chemical and Biochemical Analysis Systems into a Glass Microchip

“…21 Since the photomask had three independent channel patterns for one microchannel, the three channels were isotropically etched independently on the glass substrate initially. The depth and width of the microchannels grew as time passed.…”

“…7. 21 The microchip consists of two different areas: the former is the reaction and extraction area and the latter is the washing, i.e. decomposition and removal, area.…”