(723a) Spatial Confined Capillary Flow and Precisely Controlled Crystallization Via 3D Printed Platform: A Comprehensive View

Spatial Confined Capillary Flow
and Precisely Controlled Crystallization via 3D Printed Platform: A
Comprehensive View

Mingguang Han, Gaohong He, Xiaobin Jiang*

State Key Laboratory of Fine Chemicals, Research
and Development Center of Membrane Science and Technology, School of Chemical Engineering,
Dalian University of Technology, Dalian, P. R. China

*Corresponding author: Email: xbjiang@dlut.edu.cn

Abstract

Precision crystallization control is crucial problem
for crystallization progress design and industrial crystallization optimization
in crystallizer designing, which was widely applied in pharmacy. Pacing the
development of high precision manufacture method, micro-level or even nano
level microfluidic chip and stable microwell array chip was developed and
applied in recent state of the art crystallization processing research^1-4. This chips-based
crystallizer provides manageable environment control and repeatable crystal
formation or nucleation results rapidly and accurately.

Here, we developed material-free micro pillar array
chip as crystallizer utilizing high precise 3D printer (Digital Light Process
(DLP)) with systematic dripping module (shown in Fig. 1) and dripped crystal
solution drops onto the chip with different drop volume and different position
in mild evaporation surrounding condition. We also found diversified initial
contact angles when dripping different volume of drops, which possess different
liquid-air interface initially and influence capillary flow inside system impactful
for crystal formation (shown in Fig. 2).

For sessile drop, to understand evaporation condition
and crystal formed position, concentration gradient, evaporation time and
distance between formation and pillar center was encountered as variables to
measure concentration change, vapor diffusion flux and nucleation energy
barrier, and indicated the relationship of crystal form and capillary micro
flow (shown in Fig. 3); For cover drops, we raised inside capillary micro flow
by coffee ring inspiration to explain coffee-ring disappearance and guide the
stable diffusion crystal formation in concave structure with observation of
crystal form (shown in Fig. 3); For sitting drops and missing drip, some
irregular and unexpected crystal form appeared without explanation, which need
to be avoided. This method was well popularized in commercial crystal compounds
with facile management and modification for high throughout crystal production.
Meanwhile, lower concentration or even, polymorph system was probably suitable
in crystallization process.

Fig 1: (a) The
closed-up review of tunnel concave structure and (b) lattice concave structure
of designed crystallizer. (a-1) SEM image of the cross section of (a). (b-1)
SEM image of lattice concave from (b) (scale of the bar, 500 ¦Ìm). (c) The process
of dripping drop system.

Fig 2: (d-1): The
hydrophilic property of commercial 3D material shown in 50¡ãintrinsic angle.
(d-2)~(d-6):  gradient contact angle
results when dripping numerous volume liquid drops on concave structure

Fig 3: The
relationship of crystal form and capillary micro flow in sessile drop condition
and cover drop condition

Acknowledgment

We acknowledge financial
contribution from National Natural Science Foundation of China (Grant No.
21527812, 21676043, U1663223, 21606035), Changjiang Scholars Program
(T2012049), the Fundamental Research Funds for the Central Universities
(DUT16TD19, DUT17ZD203) and Education Department of the Liaoning Province of
China (No. LT2015007).

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