This document discusses the simulation of biofilm formation under flow conditions using multi-well microplates. Shear strain values up to 150 s-1 were obtained in 96-well microplates shaken at frequencies between 50-200 rpm and diameters of 25-100 mm. These values are within the range found in arteries, veins and the oral cavity. Shear stresses from 0.008-0.07 Pa and shear strain rates of 5-42 s-1 were obtained in 12-well microplates shaken at frequencies from 40-180 rpm. The 12-well format allows testing of various materials for biomedical applications by placing coupons on the bottom wells under relevant flow conditions.

1. Gomes L.C.1*, Miranda J.M.2, Mergulhão F.J.1
1 LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal
2 CEFT - Transport Phenomena Research Center, Faculty of Engineering, University of Porto, Porto, Portugal
* luciana.gomes@fe.up.pt
COSTAMiCIWorkshop,7March2019,Riga,Latvia
ABSTRACT
Biofilms are problematic in the health sector since
they are responsible for 65% of the hospital acquired
infections associated with medical devices.
Hydrodynamics have a very strong influence in the
process of biofilm formation.
Flow behavior in 96-well microtiter plates (MTPs)
was simulated for shaking frequencies between 50
and 200 rpm and diameters from 25 to 100 mm.
Shear strain values up to 150 s-1 were obtained.
These values are within the range of those found in
arteries and veins, and also in the oral cavity.
Using 12-well microplates is advantageous due to
the relatively high shear forces that can be obtained
with this format. Large coupons can be placed on the
bottom of the wells, thus several antimicrobial
materials for biomedical applications can be tested.
Microplates for simulating biofilms formed in medical devices
REFERENCES
(a) Gomes LC, Moreira JMR, Teodósio JS, Araújo JDP, Miranda JM, Simões M, Melo LF, Mergulhão FJ.
2014. 96-well microtiter plates for biofouling simulation in biomedical settings. Biofouling. 30:535-546.
(b) Gomes LC, Moreira JMR, Simões M, Melo LF, Mergulhão FJ. 2014. Biofilm localization in the vertical
wall of shaking 96-well plates. Scientifica. 231083:13.
(c) Gomes LC, Miranda JM, Mergulhão FJ. 2019. Operation of Biofilm Reactors for the Food Industry
using CFD. In: Computational Fluid Dynamics in Food Processing, 2nd Edition (Sun D-W, ed), pp 559-
588, CRC Press.
This work was financially supported by: project UID/EQU/00511/2019 - Laboratory for Process Engineering, Environment,
Biotechnology and Energy – LEPABE funded by national funds through FCT/MCTES (PIDDAC), and project “LEPABE-2-ECO-
INNOVATION” – NORTE‐01‐0145‐FEDER‐000005, funded by Norte Portugal Regional Operational Programme (NORTE 2020),
under PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Support from the EU
COST Action AMiCI (CA15114) is acknowledged.
ACKNOWLEDGMENTS:
CONCLUSIONS
 The 96-well MTP is a powerful platform to reproduce the hydrodynamic forces found in
some medical scenarios and to be used, for instance, to screen antibiofilm compounds;
 The range of shear rate values that can be obtained on the bottom of 12-well
microplates is interesting to test antimicrobial surfaces for biomedical applications.
RESULTS
METHODS
Shear strain values up to
150 s-1 can be obtained in
96-well MTPs.
Figure 1: Time averaged shear strain rates on a 96-well
MTP at different shaking frequencies and diameters.
The wall shear strain rate is not uniform,
being much higher in the air-liquid interface.
The average wall shear strain rate
increases with the shaking frequency
and orbital diameter.
Shaking frequency
96-well MTP (a)
Shakingdiameter
• shear strain rate magnitudes
for several shaking frequencies
(50 – 200 rpm) and diameters
(25 – 100 mm)
• liquid volume of 200 µL
• temperature of 30 °C
Biofilm formation was different in different well locations (b):
SEM micrographs
shaking diameter of 50 mm;
150 rpm
These values are in the range
of those found in blood
circulation in arteries and
veins, and in the oral cavity.
Figure 2: Shear strain rate as a function of shaking frequency
for different shaking diameters. The grey shading includes
some shear strain rates values of medical scenarios.
Figure 3: Shear stress magnitudes (Pa) on the bottom of 12-well microplates shaken with an orbital diameter of 25 mm.
12-well microplate (c)
40 rpm 100 rpm 140 rpm 180 rpm
Shear stress: 0.008 – 0.07 Pa
Shear strain rate: 5 – 42 s-1
Coupons can be placed on the
bottom of the wells, so that
different materials for biomedical
applications can be tested.
The flow behavior inside the wells of 96- and 12-well microplates was
numerical simulated using ANSYS Fluent™ and the volume of fluid
(VOF) methodology.
• shear strain rate and shear
stress magnitudes on the
bottom for a shaking
diameter of 25 mm and
several frequencies (40,
100, 140 and 180 rpm)
• liquid volume of 3 mL
• temperature of 25 °C
96-well MTP
orbital incubator
12-well microplates
Computational fluid dynamics (CFD)