Capillary-Assembled Microchip for Universal Integration of Various Chemical Functions onto a Single Microfluidic Device

Abstract

A novel concept for assembling various chemical functions onto a single microfluidic device is proposed. The concept, called a capillary-assembled microchip, involves embedding chemically functionalized capillaries into a lattice microchannel network fabricated on poly(dimethylsiloxane) (PDMS). The network has the same channel dimensions as the outer dimensions of the capillaries. In this paper, we focus on square capillaries to be embedded into a PDMS microchannel network having a square cross section. The combination of hard glass square capillary and soft square PDMS channel allows successful fabrication of a microfluidic device without any solution leakage, and which can use diffusion-based two-solution mixing. Two different types of chemically modified capillaries, an ion-sensing capillary and a pH-sensing capillary, are prepared by coating a hydrophobic plasticized poly(vinyl chloride) membrane and a hydrophilic poly(ethyleneglycol) membrane containing functional molecules onto the inner surface of capillaries. Then, they are cut into appropriate lengths and arranged on a single microchip to prepare a dual-analyte sensing system. The concept proposed here offers advantages inherent to using a planar microfluidic device and of chemical functionality of immobilized molecules. Therefore, we expect to fabricate various types of chemically functionalized microfluidic devices soon.

Advancements in Capillary-Assembled Microchip (CAs-CHIP) Development for Multiple Analyte Sensing and Microchip Electrophoresis

“…34 Figure 1(a) depicts the general fabrication of the first-generation CAs-CHIP. The lattice PDMS microchannel network is fabricated with the commonly used soft lithographic technique.…”

“Drop-and-Sip” Fluid Handling Technique for the Reagent-Release Capillary (RRC)-based Capillary-Assembled Microchip (CAs-CHIP): Sample Delivery Optimization and Reagent Release Behavior in RRC

“…The fabrication procedure of the lattice microchannel on a PDMS plate has already been reported elsewhere. 10 Briefly, a glass mold with a lattice structure was prepared by cutting a 300-mm depth with a 1-mm pitch using a dicing saw possessing an edge of 300-μm width. Then, conventional PDMS molding processes with a glass mold were carried out to prepare a PDMS mold.…”

“…1). 10 Our group have demonstrated various applications of CAs-CHIP in terms of multiple chemical and biochemical function integration like simultaneous multi-ion and enzymatic sensing, 11 valving and enzyme-activity sensing, 12 multi-ion sensing, 13 microchipelectrophoresis with protein pretreatment element, 14 ELISArelated technique, 15,16 and electrochemical glucose sensing. 17 In addition, the "drop-and-sip" fluid handling technique operates by dropping a few microliters of sample solution on the inlet hole of the CAs-CHIP; then a negative pressure was applied on the opposite hole (outlet hole) using either a syringe pump or a micropipette.…”

Fast and Single-step Fluorescence-based Competitive Bioassay Microdevice Combined PDMS Microchannel Arrays Separately Immobilizing Graphene Oxide-Analyte Conjugates and Fluorescently-labelled Receptor Proteins

“…[5][6][7][8] However, simultaneously solving these problems is still challenging. Recently, we proposed designing "singlestep" microdevices based on square glass capillaries [9][10][11][12][13] or polymer capillaries. [14][15][16] For these approaches, the inner capillary wall is functionalized by physical adsorption or covalent bonding of analytical reagents or by coating the wall with reagent-containing films.…”