Polydimethylsiloxane (PDMS) is extensively used in clinical flexible electronics, due to its biocompatibility and stability. When it is employed in a stretchable epidermal sensor for long-term monitoring, PDMS must have open pores within it to assure the sweat penetration. In the present paper, we focus on the mechanical properties of porous PDMS with different volume porosities at different temperatures. The emulsion polymerization technique is applied to fabricate porous PDMS. By controlling the ratio of water to PDMS prepolymer, different porosities of PDMS were obtained, and elastic moduli of such porous PDMS were measured in experiment. Results indicate that the elastic modulus increases nonlinearly as its temperature rises from 0 °C to 40 °C (a temperature range frequently encountered in clinical applications). Meanwhile, an asymptotic homogenization method (AHM) is employed to theoretically predict the elastic modulus and Poisson's ratio of porous PDMS, whose reliability is testified by comparing the results with experimentally measured data. Further theoretical discussions on mechanical properties are carried out, and results show that the pore size of porous PDMS has almost no effect on the elastic modulus and Poisson's ratio for certain porosities. Porosity of porous PDMS, however, has significant effect on both of these two mechanical parameters. Two fitted nonlinear formulas are then proposed to estimate the elastic modulus and Poisson's ratio of porous PDMS for any volume porosity less than 50%. All the results in the present paper are essential for mechanical design and optimization of clinical flexible electronics based on porous PDMS.

References

References
1.
Kirstie
,
P.
,
Evans
,
P.
, and
Harrison
,
D.
,
2005
, “
The Origins and Evolution of the PCB: A Review
,”
Circuit World
,
31
(
1
), pp.
41
45
.
2.
Ko
,
H. C.
,
Stoykovich
,
M. P.
,
Song
,
J. Z.
,
Malyarchuk
,
V.
,
Choi
,
W. M.
,
Chang
,
J. Y.
,
Geddes
,
J.
,
Xiao
,
J. L.
,
Wang
,
S. D.
,
Huang
,
Y.
, and
Rogers
,
J. A.
,
2008
, “
A Hemispherical Electronic Eye Camera Based on Compressible Silicon Optoelectronics
,”
Nature
,
454
(
7205
), pp.
748
753
.
3.
,
C.
,
Li
,
M.
,
Xiao
,
J.
,
Jung
,
I.
,
Wu
,
J.
,
Huang
,
Y.
,
Hwang
,
K. C.
, and
Rogers
,
J. A.
,
2013
, “
Mechanics of Tunable Hemispherical Electronic Eye Camera Systems That Combine Rigid Device Elements With Soft Elastomers
,”
ASME J. Appl. Mech.
,
80
(
6
), p.
061022
.
4.
Park
,
S. I.
,
Xiong
,
Y.
,
Kim
,
R. H.
,
Elvikis
,
P.
,
Meitl
,
M.
,
Kim
,
D. H.
,
Wu
,
J.
,
Yoon
,
J.
,
Yu
,
C. J.
,
Liu
,
Z.
,
Huang
,
Y.
,
Hwang
,
K. C.
,
Ferreira
,
P.
,
Li
,
X.
,
Choquette
,
K.
, and
Rogers
,
J. A.
,
2009
, “
Printed Assemblies of Inorganic Light-Emitting Diodes for Deformable and Semitransparent Displays
,”
Science
,
325
(
5943
), pp.
977
981
.
5.
Yeo
,
W. H.
,
Kim
,
Y. S.
,
Lee
,
J.
,
Ameen
,
A.
,
Shi
,
L.
,
Li
,
M.
,
Wang
,
S.
,
Ma
,
R.
,
Jin
,
S. H.
,
Kang
,
Z.
,
Huang
,
Y.
, and
Rogers
,
J. A.
,
2013
, “
Multifunctional Epidermal Electronics Printed Directly Onto the Skin
,”
Adv. Mater.
,
25
(
20
), pp.
2773
2778
.
6.
Li
,
Y. H.
,
Zhang
,
J. P.
,
Xing
,
Y. F.
, and
Song
,
J. Z.
,
2017
, “
Thermo-Mechanical Analysis of Epidermal Electronic Devices Integrated With Human Skin
,”
ASME J. Appl. Mech.
,
84
(
11
), p.
111004
.
7.
Xu
,
W.
, and
Lu
,
T. J.
,
2008
, “
Flexible Electronics System and Their Mechanical Properties
,”
Adv. Mech.
,
38
(
2
), pp.
137
150
(in Chinese).
8.
Meng
,
X. H.
,
Liu
,
B. Y.
,
Wang
,
Y.
,
Zhang
,
T. H.
, and
Xiao
,
J. L.
,
2016
, “
Third-Order Polynomials Model for Analyzing Multilayer Hard/Soft Materials in Flexible Electronics
,”
ASME J. Appl. Mech.
,
83
(
8
), p.
081011
.
9.
Yuan
,
J. H.
,
Pharr
,
M.
,
Feng
,
X.
,
Rogers
,
J. A.
, and
Huang
,
Y.
,
2016
, “
Design of Stretchable Electronics Against Impact
,”
ASME J. Appl. Mech.
,
83
(
10
), p.
101009
.
10.
Jin
,
C. R.
, and
Qiao
,
Q. C.
,
2016
, “
Deformation of Pyramidal PDMS Stamps During Microcontact Printing
,”
ASME J. Appl. Mech.
,
83
(
7
), p.
071011
.
11.
Gao
,
Y. Y.
,
Li
,
Y. H.
,
Li
,
R.
, and
Song
,
J. Z.
,
2017
, “
An Accurate Thermomechanical Model for Laser-Driven Microtransfer Printing
,”
ASME J. Appl. Mech.
,
84
(
6
), p.
064501
.
12.
Wang
,
H. Y.
,
Kobayashi
,
T.
,
Saitoh
,
H.
, and
Fujii
,
N.
,
1996
, “
Porous Polydimethylsiloxane Membranes for Enzyme Immobilization
,”
J. Appl. Polym. Sci.
,
60
(
13
), pp.
2339
2346
.
13.
Dufaud
,
O.
,
Favre
,
E.
, and
Sadtler
,
V.
,
2010
, “
Porous Elastomeric Beads From Crosslinked Emulsions
,”
J. Appl. Polym. Sci.
,
83
(
5
), pp.
967
971
.
14.
Juchniewicz
,
M.
,
Stadnik
,
D.
,
Biesiada
,
K.
,
Olszyna
,
K.
,
Chudy
,
M.
,
Brzózka
,
Z.
, and
Dybko
,
A.
,
2007
, “
Porous Crosslinked PDMS-Microchannel Coatings
,”
Sens. Actuators, B
,
126
(
1
), pp.
68
72
.
15.
Lantada
,
A. D.
,
Iniesta
,
H. A.
,
Sánchez
,
B. P.
, and
García-Ruíz
,
J. P.
,
2014
, “
Free-Form Rapid Prototyped Porous PDMS Scaffolds Incorporating Growth Factors Promote Chondrogenesis
,”
Adv. Mater. Sci. Eng.
,
2014
, p.
612976
.
16.
Yuen
,
P. K.
,
Su
,
H.
,
Goral
,
V. N.
, and
Fink
,
K. A.
,
2011
, “
Three-Dimensional Interconnected Microporous Poly(Dimethylsiloxane) Microfluidic Devices
,”
Lab Chip
,
11
(
8
), pp.
1541
1544
.
17.
Khanafer
,
K.
,
Duprey
,
A.
,
Schlicht
,
M.
, and
Berguer
,
R.
,
2009
, “
Effects of Strain Rate, Mixing Ratio, and Stress-Strain Definition on the Mechanical Behavior of the Polydimethylsiloxane (PDMS) Material as Related to Its Biological Applications
,”
Biomed. Microdevices
,
11
(
2
), pp.
503
508
.
18.
Liu
,
M.
,
Sun
,
J. R.
,
Sun
,
Y.
,
Bock
,
C.
, and
Chen
,
Q. F.
,
2009
, “
Thickness-Dependent Mechanical Properties of Polydimethylsiloxane Membranes
,”
J. Micromech. Microeng.
,
19
(
3
), p.
035028
.
19.
Liu
,
M.
,
Sun
,
J. R.
, and
Chen
,
Q. F.
,
2009
, “
Influences of Heating Temperature on Mechanical Properties of Polydimethylsiloxane
,”
Sens. Actuators, A
,
151
(
1
), pp.
42
45
.
20.
Schneider
,
F.
,
Fellner
,
T.
,
Wilde
,
J.
, and
Wallrabe
,
U.
,
2008
, “
Mechanical Properties of Silicones for MEMS
,”
J. Micromech. Microeng.
,
18
(
6
), p.
065008
.
21.
Johnston
,
I. D.
,
Mccluskey
,
D. K.
,
Tan
,
C. K. L.
, and
Tracey
,
M. C.
,
2014
, “
Mechanical Characterization of Bulk Sylgard 184 for Microfluidics and Microengineering
,”
J. Micromech. Microeng.
,
24
(
3
), p.
035017
.
22.
Hassani
,
B.
, and
Hinton
,
E.
,
1998
, “
A Review of Homogenization and Topology Optimization I-Homogenization Theory for Media With Periodic Structure
,”
Comput. Struct.
,
69
(
6
), pp.
707
717
.
23.
Cheng
,
G. D.
,
Cai
,
Y. W.
, and
Xu
,
L.
,
2013
, “
Novel Implementation of Homogenization Method to Predict Effective Properties of Periodic Materials
,”
Acta Mech. Sin.
,
29
(
4
), pp.
550
556
.
24.
Hassani
,
B.
, and
Hinton
,
E.
,
1998
, “
A Review of Homogenization and Topology Optimization II-Analytical and Numerical Solution of Homogenization Equations
,”
Comput. Struct.
,
69
(
6
), pp.
719
738
.
25.
Yeh
,
C. N.
,
2009
, “PDMS Ferroelectrets for Transducers,” Master dissertation, National Tsing Hua University, Taiwan, China.
You do not currently have access to this content.