Nak-Chul Choi, Simon Song School of Mechanical Engineering

Development of sensor bead according to solidifying PCDA-ME polymer microdroplet
Nak-Chul Choi, Simon Song
School of Mechanical Engineering, Hanyang University
Abstract
Surface Treatment
In this study, we address fabrication process of PCDA-ME polymer
microsensor using microfludic technique. PCDA-ME polymer has
unique optical properties that show color change and fluorescence
emission depending on temperature change, which helps PCDA-ME
sensor to be applied in detecting heat energy. However, it is difficult
to prepare an activated PCDA-ME sensor because it requires
Polyaniline
(PANI)
complicated
activation
process such as simultaneous refrigeration
and UV exposure in short time. Thus, we present a novel platform to
fabricate and activate the PCDA-ME microbead sensor using 2-D
hydrodynamic focusing technique in microfluidic chip, and then,
evaluate proper sensing performance of PCDA-ME mcirobead sensor
qualitatively by observing the visible and fluorescent images.
Polymer PCDA-ME and PDMS indicates the nature of the
hydrophobic. To create a PCDA-ME droplet, surface modification of
PDMS microchannel is an essential process. So, chemically PDMS
surface reforms hydrophilic using oxygen plasma treatment.
PCDA-ME
PCDA-ME is a type of polymer with thermal-sensitivity and it has
relatively high freezing point of about 18 ˚C. The PCDA-ME can be
activated by 254 nm UV exposure immediately after solidification
process by refrigeration under the freezing point. Through activation
process, the PCDA-ME change its transparent color to visible blue,
and then it shows visible red and fluorescence emission when it is
exposed to thermal stimulation such as IR (460~495 nm) and other
heat source. These optical properties allows PCDA-ME polymer
sensor to be widely used as a heat energy detector.
Experimental Setup

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Core fluid : liquid PCDA-ME polymer
Sheath fluid : DI-water + Glycerin (1:2wt%)
Core flow rate : 0.05~0.1mL/h
Sheath flow rate : 0.1~1mL/h
PCDA-ME Microdroplet
 Fabrication of PCDA-ME microdroplet
2-D Hydrodynamic Focusing
Technique
 Activation and fluorescence emission of PCDA-ME microbead
 2D Hydrodynamic focusing technique is that droplet is fabricated
by shear force of sheath flow acts on the sample flow.
 Hydrodynamic focusing technique can be mass production of the
same size droplet.
Objective
1) To fabricate PCDA-ME microdroplet on a microfluidic chip using
2-D hydrodynamic focusing technique.
2) To study the effects of the flow rate on the size of PCDA-ME
microdroplet.
3) To examine the effects of the temperature on the characteristics
of PCDA-ME microdroplet.
4) To examine the effects of the UV and IR on the characteristics
of PCDA-ME microbead.
Future Plans
 Fabrication of spherical activated PCDA-ME microdbead
 Fabrication a variety of size microbead
 Verify whether microbead is suitable as sensor