Hydrogels are a critical component of many microfluidic devices. They have been used in cell culture applications, biosensors, gradient generators, separation microdevices, micro-actuators, and microvalves. Various techniques have been utilized to integrate hydrogels into microfluidic devices such as flow confinement and gel photopolymerization. However, in these methods, hydrogels are typically introduced in post processing steps which add complexity, cost, and extensive fabrication steps to the integration process and can be prone to user induced variations. Here, we introduce an inexpensive method to locally integrate hydrogels into microfluidic devices during the fabrication process without the need for post-processing. In this method, porous and fibrous membranes such as electrospun membranes are used as scaffolds to hold gels and they are patterned using xurography. Hydrogels in various shapes as small as 200 μm can be patterned using this method in a scalable manner. The electrospun scaffold facilitates drying and reconstitution of these gels without loss of shape or leakage that is beneficial in a number of applications. Such reconstitution is not feasible using other hydrogel integration techniques. Therefore, this method is suitable for long time storage of hydrogels in devices which is useful in point-of-care (POC) devices. This hydrogel integration method was used to demonstrate gel electrophoretic concentration and quantification of short DNA (150 bp) with different concentrations in rehydrated agarose embedded in electrospun polycaprolactone (PCL) membrane. This can be developed further to create a POC device to quantify cell-free DNA, which is a prognostic biomarker for severe sepsis patients.

1.
Ahmed
,
E. M.
, “
Hydrogel: Preparation, characterization, and applications: A review
,”
J. Adv. Res.
6
(
2
),
105
121
(
2015
).
2.
Angus
,
D. C.
,
Linde-Zwirble
,
W. T.
,
Lidicker
,
J.
,
Clermont
,
G.
,
Carcillo
,
J.
, and
Pinsky
,
M. R.
, “
Epidemiology of severe sepsis in the United States: Analysis of incidence, outcome, and associated costs of care
,”
Crit. Care Med.| Soc. Crit. Care Med.
29
(
7
),
1303
1310
(
2001
).
3.
Aymerich
,
J.
,
Márquez
,
A.
,
Terés
,
L.
,
Muñoz-Berbel
,
X.
,
Jiménez
,
C.
,
Domínguez
,
C.
,
Serra-Graells
,
F.
, and
Dei
,
M.
, “
Cost-effective smartphone-based reconfigurable electrochemical instrument for alcohol determination in whole blood samples
,”
Biosens. Bioelectron.
117
,
736
742
(
2018
).
4.
Bachmann
,
B.
,
Spitz
,
S.
,
Rothbauer
,
M.
,
Jordan
,
C.
,
Purtscher
,
M.
,
Zirath
,
H.
,
Schuller
,
P.
,
Eilenberger
,
C.
,
Ali
,
S. F.
, and
Mühleder
,
S.
, “
Engineering of three-dimensional pre-vascular networks within fibrin hydrogel constructs by microfluidic control over reciprocal cell signaling
,”
Biomicrofluidics
12
(
4
),
042216
(
2018
).
5.
Bartholomeusz
,
D. A.
,
Boutté
,
R. W.
, and
Andrade
,
J. D.
, “
Xurography: Rapid prototyping of microstructures using a cutting plotter
,”
J. Microelectromech. Syst.
14
(
6
),
1364
1374
(
2005
).
6.
Beck
,
A.
,
Obst
,
F.
,
Busek
,
M.
,
Grünzner
,
S.
,
Mehner
,
P. J.
,
Paschew
,
G.
,
Appelhans
,
D.
,
Voit
,
B.
, and
Richter
,
A.
, “
Hydrogel patterns in microfluidic devices by do-it-yourself UV-photolithography suitable for very large-scale integration
,”
Micromachines
11
(
5
),
479
(
2020
).
7.
Beebe
,
D. J.
,
Moore
,
J. S.
,
Bauer
,
J. M.
,
Yu
,
Q.
,
Liu
,
R. H.
,
Devadoss
,
C.
, and
Jo
,
B.-H.
, “
Functional hydrogel structures for autonomous flow control inside microfluidic channels
,”
Nature
404
(
6778
),
588
590
(
2000
).
8.
Cassano
,
C. L.
,
Simon
,
A. J.
,
Liu
,
W.
,
Fredrickson
,
C.
, and
Hugh Fan
,
Z.
, “
Use of vacuum bagging for fabricating thermoplastic microfluidic devices
,”
Lab Chip
15
(
1
),
62
66
(
2015
).
9.
Chen
,
L.
,
Wang
,
K. X.
, and
Doyle
,
P. S.
, “
Effect of internal architecture on microgel deformation in microfluidic constrictions
,”
Soft Matter
13
(
9
),
1920
1928
(
2017
).
10.
Chung
,
S.
,
Sudo
,
R.
,
Mack
,
P. J.
,
Wan
,
C.-R.
,
Vickerman
,
V.
, and
Kamm
,
R. D.
, “
Cell migration into scaffolds under co-culture conditions in a microfluidic platform
,”
Lab Chip
9
(
2
),
269
275
(
2009
).
11.
Duan
,
K.
,
Ghosh
,
G.
, and
Lo
,
J. F.
, “
Optimizing multiplexed detections of diabetes antibodies via quantitative microfluidic droplet array
,”
Small
13
(
46
),
1702323
(
2017
).
12.
Dwivedi
,
D. J.
,
Toltl
,
L. J.
,
Swystun
,
L. L.
,
Pogue
,
J.
,
Liaw
,
K.-L.
,
Weitz
,
J. I.
,
Cook
,
D. J.
,
Fox-Robichaud
,
A. E.
,
Liaw
,
P. C.
, and Canadian Critical Care Translational Biology Group, “
Prognostic utility and characterization of cell-free DNA in patients with severe sepsis
,”
Crit. Care
16
(
4
),
R151
(
2012
).
13.
Eker
,
B.
,
Temiz
,
Y.
, and
Delamarche
,
E.
, “
Heterogeneous integration of gels into microfluidics using a mesh carrier
,”
Biomed. Microdevices
16
(
6
),
829
835
(
2014
).
14.
Fang
,
X.
,
Wei
,
S.
, and
Kong
,
J.
, “
Based microfluidics with high resolution, cut on a glass fiber membrane for bioassays
,”
Lab Chip
14
(
5
),
911
915
(
2014
).
15.
Gao
,
D.
,
Liu
,
J.
,
Wei
,
H.-B.
,
Li
,
H.-F.
,
Guo
,
G.-S.
, and
Lin
,
J.-M.
, “
A microfluidic approach for anticancer drug analysis based on hydrogel encapsulated tumor cells
,”
Anal. Chim. Acta
665
(
1
),
7
14
(
2010
).
16.
Garcia-Schwarz
,
G.
and
Santiago
,
J. G.
, “
Integration of on-chip isotachophoresis and functionalized hydrogels for enhanced-sensitivity nucleic acid detection
,”
Anal. Chem.
84
(
15
),
6366
6369
(
2012
).
17.
Gerver
,
R. E.
and
Herr
,
A. E.
, “
Microfluidic western blotting of low-molecular-mass proteins
,”
Anal. Chem.
86
(
21
),
10625
10632
(
2014
).
18.
Glavan
,
A. C.
,
Martinez
,
R. V.
,
Maxwell
,
E. J.
,
Subramaniam
,
A. B.
,
Nunes
,
R. M.
,
Soh
,
S.
, and
Whitesides
,
G. M.
, “
Rapid fabrication of pressure-driven open-channel microfluidic devices in omniphobic RF paper
,”
Lab Chip
13
(
15
),
2922
2930
(
2013
).
19.
Goy
,
C. B.
,
Chaile
,
R. E.
, and
Madrid
,
R. E.
, “
Microfluidics and hydrogel: A powerful combination
,”
React. Funct. Polym.
145
,
104314
(
2019
).
20.
Harmon
,
M. E.
,
Tang
,
M.
, and
Frank
,
C. W.
, “
A microfluidic actuator based on thermoresponsive hydrogels
,”
Polymer
44
(
16
),
4547
4556
(
2003
).
21.
Heo
,
J.
and
Crooks
,
R. M.
, “
Microfluidic biosensor based on an array of hydrogel-entrapped enzymes
,”
Anal. Chem.
77
(
21
),
6843
6851
(
2005
).
22.
Herzog
,
C.
,
Poehler
,
E.
,
Peretzki
,
A. J.
,
Borisov
,
S. M.
,
Aigner
,
D.
,
Mayr
,
T.
, and
Nagl
,
S.
, “
Continuous on-chip fluorescence labelling, free-flow isoelectric focusing and marker-free isoelectric point determination of proteins and peptides
,”
Lab Chip
16
(
9
),
1565
1572
(
2016
).
23.
Islam
,
M.
,
Natu
,
R.
, and
Martinez-Duarte
,
R.
, “
A study on the limits and advantages of using a desktop cutter plotter to fabricate microfluidic networks
,”
Microfluid. Nanofluid.
19
(
4
),
973
985
(
2015
).
24.
Jung
,
Y. K.
,
Kim
,
J.
, and
Mathies
,
R. A.
, “
Microfluidic linear hydrogel array for multiplexed single nucleotide polymorphism (SNP) detection
,”
Anal. Chem.
87
(
6
),
3165
3170
(
2015
).
25.
Jung
,
Y. K.
,
Kim
,
J.
, and
Mathies
,
R. A.
, “
Microfluidic hydrogel arrays for direct genotyping of clinical samples
,”
Biosens. Bioelectron.
79
,
371
378
(
2016
).
26.
Koh
,
W.-G.
,
Itle
,
L. J.
, and
Pishko
,
M. V.
, “
Molding of hydrogel microstructures to create multiphenotype cell microarrays
,”
Anal. Chem.
75
(
21
),
5783
5789
(
2003
).
27.
Koh
,
W.-G.
and
Pishko
,
M.
, “
Immobilization of multi-enzyme microreactors inside microfluidic devices
,”
Sens. Actuators, B
106
(
1
),
335
342
(
2005
).
28.
Lin
,
R.-Z.
,
Hatch
,
A.
,
Antontsev
,
V. G.
,
Murthy
,
S. K.
, and
Melero-Martin
,
J. M.
, “
Microfluidic capture of endothelial colony-forming cells from human adult peripheral blood: Phenotypic and functional validation in vivo
,”
Tissue Eng. Part C: Methods
21
(
3
),
274
283
(
2015
).
29.
Liu
,
J.
,
Gao
,
D.
,
Li
,
H.-F.
, and
Lin
,
J.-M.
, “
Controlled photopolymerization of hydrogel microstructures inside microchannels for bioassays
,”
Lab Chip
9
(
9
),
1301
1305
(
2009
).
30.
Liu
,
Z.-B.
,
Zhang
,
Y.
,
Yu
,
J.-J.
,
Mak
,
A. F.-T.
,
Li
,
Y.
, and
Yang
,
M.
, “
A microfluidic chip with poly (ethylene glycol) hydrogel microarray on nanoporous alumina membrane for cell patterning and drug testing
,”
Sens. Actuators, B
143
(
2
),
776
783
(
2010
).
31.
Luo
,
X.
,
Shen
,
K.
,
Luo
,
C.
,
Ji
,
H.
,
Ouyang
,
Q.
, and
Chen
,
Y.
, “
An automatic microturbidostat for bacterial culture at constant density
,”
Biomed. Microdevices
12
(
3
),
499
503
(
2010
).
32.
Matharu
,
Z.
,
Enomoto
,
J.
, and
Revzin
,
A.
, “
Miniature enzyme-based electrodes for detection of hydrogen peroxide release from alcohol-injured hepatocytes
,”
Anal. Chem.
85
(
2
),
932
939
(
2013
).
33.
Mochane
,
M. J.
,
Motsoeneng
,
T. S.
,
Sadiku
,
E. R.
,
Mokhena
,
T. C.
, and
Sefadi
,
J. S.
, “
Morphology and properties of electrospun PCL and its composites for medical applications: A mini review
,”
Appl. Sci.
9
(
11
),
2205
(
2019
).
34.
Mohamadi
,
R. M.
,
Svobodova
,
Z.
,
Bilkova
,
Z.
,
Otto
,
M.
,
Taverna
,
M.
,
Descroix
,
S.
, and
Viovy
,
J.-L.
, “
An integrated microfluidic chip for immunocapture, preconcentration and separation of β-amyloid peptides
,”
Biomicrofluidics
9
(
5
),
054117
(
2015
).
35.
Mohammadzadeh
,
A.
,
Fox-Robichaud
,
A. E.
, and
Selvaganapathy
,
P. R.
, “
Rapid and inexpensive method for fabrication of multi-material multi-layer microfluidic devices
,”
J. Micromech. Microeng.
29
(
1
),
015013
(
2018
).
36.
Mohammadzadeh
,
A.
,
Robichaud
,
A. E. F.
, and
Selvaganapathy
,
P. R.
, “
Rapid and inexpensive method for fabrication and integration of electrodes in microfluidic devices
,”
J. Microelectromech. Syst.
28
(
4
),
597
605
(
2019
).
37.
Nash
,
A. T.
,
Foster
,
D. A.
,
Thompson
,
S. I.
,
Han
,
S.
,
Fernandez
,
M. K.
, and
Hwang
,
D. K.
, “
A new rapid microfluidic detection platform utilizing hydrogel-membrane under cross-flow
,”
Adv. Mater. Technol.
7
,
2101396
(
2022
).
38.
Nguyen
,
H.-T.
,
Massino
,
M.
,
Keita
,
C.
, and
Salmon
,
J.-B.
, “
Microfluidic dialysis using photo-patterned hydrogel membranes in PDMS chips
,”
Lab Chip
20
(
13
),
2383
2393
(
2020
).
39.
Nie
,
J.
,
Fu
,
J.
, and
He
,
Y.
, “
Hydrogels: The next generation body materials for microfluidic chips?
,”
Small
16
(
46
),
2003797
(
2020
).
40.
Pandey
,
C. M.
,
Augustine
,
S.
,
Kumar
,
S.
,
Kumar
,
S.
,
Nara
,
S.
,
Srivastava
,
S.
, and
Malhotra
,
B. D.
, “
Microfluidics based point-of-care diagnostics
,”
Biotechnol. J.
13
(
1
),
1700047
(
2018
).
41.
Paustian
,
J. S.
,
Azevedo
,
R. N.
,
Lundin
,
S.-T. B.
,
Gilkey
,
M. J.
, and
Squires
,
T. M.
, “
Microfluidic microdialysis: Spatiotemporal control over solution microenvironments using integrated hydrogel membrane microwindows
,”
Phys. Rev. X
3
(
4
),
041010
(
2013
).
42.
Poehler
,
E.
,
Herzog
,
C.
,
Lotter
,
C.
,
Pfeiffer
,
S. A.
,
Aigner
,
D.
,
Mayr
,
T.
, and
Nagl
,
S.
, “
Label-free microfluidic free-flow isoelectric focusing, pH gradient sensing and near real-time isoelectric point determination of biomolecules and blood plasma fractions
,”
Analyst
140
(
22
),
7496
7502
(
2015
).
43.
Puchberger-Enengl
,
D.
,
Krutzler
,
C.
,
Keplinger
,
F.
, and
Vellekoop
,
M. J.
, “
Single-step design of hydrogel-based microfluidic assays for rapid diagnostics
,”
Lab Chip
14
(
2
),
378
383
(
2014
).
44.
Samae
,
M.
,
Ritmetee
,
P.
,
Chirasatitsin
,
S.
,
Kojić
,
S.
,
Kojić
,
T.
,
Jevremov
,
J.
,
Stojanović
,
G.
, and
Al Salami
,
H.
, “
Precise manufacturing and performance validation of paper-based passive microfluidic micromixers
,”
Int. J. Precision Eng. Manuf.
21
(
3
),
499
508
(
2020
).
45.
Samprovalaki
,
K.
,
Robbins
,
P.
, and
Fryer
,
P.
, “
Investigation of the diffusion of dyes in agar gels
,”
J. Food Eng.
111
(
4
),
537
545
(
2012
).
46.
Shah
,
K. G.
and
Yager
,
P.
, “
Wavelengths and lifetimes of paper autofluorescence: A simple substrate screening process to enhance the sensitivity of fluorescence-based assays in paper
,”
Anal. Chem.
89
(
22
),
12023
12029
(
2017
).
47.
Stojanović
,
G.
,
Paroški
,
M.
,
Samardžić
,
N.
,
Radovanović
,
M.
, and
Krstić
,
D.
, “
Microfluidics-based four fundamental electronic circuit elements resistor, inductor, capacitor and memristor
,”
Electronics
8
(
9
),
960
(
2019
).
48.
Upadhyaya
,
S.
and
Selvaganapathy
,
P. R.
, “
Microfluidic devices for cell based high throughput screening
,”
Lab Chip
10
(
3
),
341
348
(
2010
).
49.
Whitesides
,
G. M.
, “
The origins and the future of microfluidics
,”
Nature
442
(
7101
),
368
373
(
2006
).
50.
Wu
,
X.
,
Newbold
,
M. A.
, and
Haynes
,
C. L.
, “
Recapitulation of in vivo-like neutrophil transendothelial migration using a microfluidic platform
,”
Analyst
140
(
15
),
5055
5064
(
2015
).
51.
Yang
,
J.
,
Selvaganapathy
,
P. R.
,
Gould
,
T. J.
,
Dwivedi
,
D. J.
,
Liu
,
D.
,
Fox-Robichaud
,
A. E.
, and
Liaw
,
P. C.
, “
A microfluidic device for rapid quantification of cell-free DNA in patients with severe sepsis
,”
Lab Chip
15
(
19
),
3925
3933
(
2015
).
52.
Yoon
,
D.
,
Kim
,
H.
,
Lee
,
E.
,
Park
,
M. H.
,
Chung
,
S.
,
Jeon
,
H.
,
Ahn
,
C.-H.
, and
Lee
,
K.
, “
Study on chemotaxis and chemokinesis of bone marrow-derived mesenchymal stem cells in hydrogel-based 3D microfluidic devices
,”
Biomater. Res.
20
(
1
),
1
8
(
2016
).
53.
Yuen
,
P. K.
and
Goral
,
V. N.
, “
Low-cost rapid prototyping of flexible microfluidic devices using a desktop digital craft cutter
,”
Lab Chip
10
(
3
),
384
387
(
2010
).
54.
Zhang
,
X.
,
Li
,
L.
, and
Luo
,
C.
, “
Gel integration for microfluidic applications
,”
Lab Chip
16
(
10
),
1757
1776
(
2016
).

Supplementary Material

You do not currently have access to this content.