ibidi Pump System
8.4
Viscosity
The viscosity influences the system in two ways: the relationship between pressure and flow rate,
and the dependence of shear stress on flow rate (Figure
). For an exact calculation of the shear
stress that the cells are being exposed to, the viscosity of the perfusion medium must be known. This
information can be obtained from the supplier or by measuring the medium with a viscometer.
The viscosity of water is 1 mPa s at 20°C; however, it is only 0.69 mPa s at 37°C (30% difference!). The
viscosity of water in relation to temperature is shown in Figure
(1 mPa s = 0.01 dyn s/cm
2
).
Figure 51: Viscosity of water as a function of temperature.
8.5
Shear Stress Calculations in ibidi Channel Slides
The wall shear stress in a µ-Slide depends on the flow rate and the viscosity of the perfusion medium.
Use the following calculations to determine the flow rates for the corresponding shear stress.
Detailed information is provided in
Application Note 11 “Shear Stress and Shear Rates”
Φ
=
flow rate
ml
min
,
τ
=
shear stress
dyn
cm
2
,
η
=
viscosity
dyn
·
s
cm
2
µ-Slide I
0.2
Luer
τ
=
η
·
512.9
·
Φ
µ-Slide I
0.2
Luer Glass Bottom
τ
=
η
·
330.4
·
Φ
µ-Slide I
0.4
Luer
τ
=
η
·
131.6
·
Φ
Instruction Manual
65
Version 2.6 (May 12, 2022)
