Imsung Yoo

A Thermoresponsive Fluorogenic Conjugated Polymer for a Temperature Sensor in Microfluidic Devices

A new, microfluidic temperature sensor system, based on a thermoresponsive conjugated polymer supramolecule, has been developed. By generating blue-phase polydiacetylene (PDA) sensor droplets using hydrodynamic instability, we were able to monitor the variation of fluorescent intensity of the droplets with respect to the flow temperature.

Size-controlled fabrication of polydiacetylene-embedded microfibers on a microfluidic chip.

A microfluidic technique was employed to fabricate polydiacetylene (PDA)-embedded hydrogel microfibers. By taking advantage of calcium ion-induced insoluble hydrogel formation, supramolecularly assembled diacetylene (DA)-surfactant complexes were successfully immobilized in the calcium alginate fibers. Thus, instantaneous microfiber formation was observed when the core flow of DA supramolecules-containing alginate solution met the sheath flow of calcium ions. UV irradiation of the resulting fibers afforded blue colored PDAs, and the formation of a conjugated polymer was confirmed by heat-induced phase transition and by Raman spectroscopy. By adjusting the core and sheath flow rates, PDA-embedded hydrogel fibers of various sizes were obtained.

Size-Controlled Fabrication of Polyaniline Microfibers Based on 3D Hydrodynamic Focusing Approach.

Owing to the relatively high conductivity and unique redox behavior, polyaniline (PANI) has been one of the most technologically promising conducting polymers. Although various methodologies have been developed, fabrication of PANI microfibers has been a challenging task owing to the poor solubility in most organic solvents. By taking advantage of a microfluidic technology and organic soluble acid labile t-Boc-protected PANI (t-Boc-PANI) as the conducting polymer precursor, fabrication of PANI microfibers in a size-controlled manner is possible. Introduction of a THF solution containing t-Boc-PANI, and dodecylbenzenesulfonic acid (DBSA) as a core flow, and water as a sheath flow into a microfluidic channel with a 3D hydrodynamic focusing effect results in crystallization of the polymer fiber. By changing the flow rate, linear PANI microfibers that range from 16.2 to 39.4 μm in diameter are readily obtained.

Microfluidic Fabrication of Conjugated Polymer Sensor Fibers

We propose a fabrication method for polydiacetylene (PDA)-embedded hydrogel microfibers on a microfluidic chip. These fibers can be applied to the detection of cyclodextrines (CDs), which are a family of sugar and aluminum ions. PDA, a family of conjugated polymers, has unique characteristics when used for a sensor, because it undergoes a blue-to-red color transition and nonfluorescence-to-fluorescence transition in response to environmental stimulation. PDAs have different sensing characteristics depending on the head group of PCDA. By taking advantage of ionic crosslinking-induced hydrogel formation and the 3D hydrodynamic focusing effect on a microfluidic chip, PCDA-EDEA-derived diacetylene (DA) monomer-embedded microfibers were successfully fabricated. UV irradiation of the fibers afforded blue-colored PDA, and the resulting blue PDA fibers underwent a phase transition to red and emitted red fluorescence upon exposure to CDs and aluminum ions. Their fluorescence intensity varied depending on the CDs and aluminum ion concentrations. This phase transition was also observed when the fibers were dried. † Corresponding Author, simonsong@hanyang.ac.kr C 2014 The Korean Society of Mechanical Engineers

Development of Polydiacetylene-Embedded Microfibers Using 3-D Hydrodynamic Focusing Technique

Polydiacetylene (PDA), conjugated polymer, is an attractive sensor material that has a unique optical property to transform its color from visible blue to fluorescent red upon environmental perturbations like heat, pH, specific metal ions, and etc. In this study, we propose a novel method to detect metal ions by using polydiacetylene (PDA)-embedded sensor microfibers fabricated with a 3-D hydrodynamic focusing technique using alginate and calcium solutions. Moreover, by changing the head groups of PDA, we successfully detected Al3+ and Zn2+ ions up to 1mM using PDA micro fibers.Copyright