Test liquids for flow testing of medical devices
When testing a new device it is best to use the liquid intended for the application i.e. blood, saliva etc. However, blood and other biological samples can be hard to source, and may require approval before testing is permitted. Worst of all is that blood etc. are to be treated as biohazardous and potentially infected with pathogens.
For this reason it is convenient to replace the biological sample for the initial testing of the flow properties of a device, with a harmless test liquid with the same fluidic properties.
For flow testing we have developed 4 test liquids:
TL1 - High visibility flow test liquid - Flows like water but with an intense
blue color for flow and leak visualization.
Formulation freely available in the public domain
TL2 - Blood plasma flow equivalent - Flows like normal blood plasma.
TL2 Datasheet - MSDS
TL3 - Whole blood flow equivalent - Flows like normal whole blood with 45% hematocrit.
TL3 Datasheet - MSDS
TL4 - Whole blood flow equivalent - Flows like normal whole blood with 70% hematocrit.
TL4 Datasheet - MSDS
TL2 and TL4 can be mixed to form any equivalent hematocrit between 0% and 70%.
These test liquids are flow equivalents. This mean that the test liquids have flow
properties; viscosity, density and surface tension similar to that of water, blood plasma
and whole blood, respectively.
The Non-Newtonian properties of blood (a shear thinning liquid, whose viscosity
decreases with the rate of shear) is matched in the whole blood test liquids.
The temperature sensitivity of surface tension, density and most importantly viscosity
are matched in the test liquids.
Whole blood and plasma are highly variable liquids. Natural variations in blood
hematocrit can give ±20% in whole blood viscosity. Natural variations in protein
concentration in plasma can give ±20% in plasma viscosity. The test liquids are
matched to the center of the normal range for viscosity, density and surface tension
of whole blood and blood plasma, respectively.
A safe and pure chemical solution
These test liquids are pure chemical solutions, and thus does not contain blood cells,
fibrinogen, proteins, antibodies, virus etc. It will therefore not perform any biological
function such as oxygen transport or clotting etc. It is not biohazardous and thus does
not require approval or strict procedures for its use.
These test liquids are water based and only contain approved food additives. Therefore they are safe and does not require special handling or procedures. Actually, it is safe to drink the test liquids, but of course we don't recommend doing so.
No cells - Since the whole blood test liquid does not contain blood cells it cannot accurately emulate whole blood in fluidic structures comparable in size to red blood cells (10 µm). We don't recommend using the whole blood test liquid for fluidic structures with diameters smaller than 20 µm.
Color - The yellow and red color of the blood equivalents are intended to signal the identity of the test liquid. The color and other optical properties of the test liquids does not, and is not intended to, match whole blood and plasma.
Our main activity is Medical Device development, with a focus on liquid handling devices. We work on client product development projects on a consultancy basis.
0% 45% 70%