You can use UL adapter for low viscosity in digital viscometer for spindle of large area and high rpm.

You could consider microfluidic techniques such as the mVROC by RheoSense (European distributor: Malvern Instruments). However, microchannels are not suitable, of course, if you have micrometer-size (or larger) particles since it will block the channels, so I would say it's limited to plasma or even serum, see link.

http://blog.rheosense.com/news/applications-serum-blood-viscosity

U (glass capillary)-viscometer is ideal for measuring the viscosity of the plasma in the minimum volume of the sample. For measuring the viscosity of the blood, I would recommend the cone/plate device produced by Brookfield. 

https://www.cannoninstrument.com/glassviscometers.htm

http://www.brookfieldengineering.com/Products/viscometers/laboratory-wb-coneplate.asp

Hi Kamil,

Gregory's suggestion of a capillary viscometer or the Brookfield cone and plate viscometer is a good one.

But I would recommend a slightly different approach for rheology: The challenge with your sample is that it's low viscosity approaches the effective range of most rheometers. But you can extend this range by using a rheometer geometry with a large surface area, typically, this is the concentric cylinder geometry or cup-and-bob geometry. You can even get a double concentric cylinder for some models.

I recommended geometry - cone /plate, based on the fact that this geometry, usually requires the smallest volume of the sample.

Gregory's suggestion of a capillary viscometer or the Brookfield cone and plate viscometer is a good one.

In the first instance can be measured easily, inexpensively and fairly accurately the viscosity of such samples using capillary viscometers by gravity.

Undoubtedly, the most suitable are rotational viscometers, allowing us to obtain flow curves, which are like rheological"fingerprint" of the tested sample

Hello all,

Sorry for delay and thanks everybody for replay! Actually, I passed through all viscometers/rheometers that you have just proposed. Actually, even if the range of viscosity seems to be good (what is written in the leaflets) they are not suitable for the shear range. I would like to measure as close as possible to 0 [1/s] to 1000 [1/s]. All those measurements, can but only for higher shear rates more than 500 [1/s], let say...Then, I loose data for the range of shear rates that is quite important for me. It seems that I need to switch either to very sensitive low torque rheometer with air/magnetic bearings or something like a rolling ball viscometer. Both are quite expensive...It seems it is very hard to find a viscometr/rheometer for low viscosity...

Hi Kamil,

You are right about the high shear rates required for the Brookfield type instruments to generate sufficient torque to give a good signal to noise ratio. They are limited by the sensitivity of the bearings on the lower end. In my opinion, either the capillary route of a rheometer with an air bearing would be your best bet. However, the capillary route would not give you the required shear rate range. That leaves you with a rheometer with an air bearing. You would need to use a double gap couette geometry to get to the low shear rates. I have measured viscosity of chloroform, which has a viscosity of about 0.5 cP at room temperature down to about 35 1/s shear rate. So, if the instrument is calibrated for the right range, you should be able to get shear rates for blood (I am guessing the viscosity of blood is the 2 - 3 cP range) down to about 5 - 10 1/s shear rates (maybe lower).

If you are looking to acquire such an instrument, let me know and I can hook you up with one. 

The problem is still price it started something like 30k euros which we do not have...anyway thanks fir answering.

Kamil, I hope by now you have found what you are looking for or even built one yourself. I am new to this site, so I hope I am not breaking any rules with my answer. Having read the comments, I might have a solution for you. Contact your nearest Anton Paar and ask them about the Lovis2000 application report (see attached here). As for the cost, you could either purchase outright, or hire it for a limited period. If you happen to work with a UK institute, I will be happy to arrange this for you. Hope this helps.

Hello,

Thank you for answering. I had contacted Anton Paar company. I had tried this viscometer. However, it takes time to measure. If I would like to measure viscosity from almost 01/s to 1000 1/s it would take almost the whole day. The measurement system seems to be  very accurate however not for fast applications. Anyway thank you again for your post.

Hi Kamil,

I don't what equipment you are using, but have you tried a double gap geometry in the couette? Depending on the size of the gap between the walls, you should be able to get reasonable torques even in the low shear rate region even for the low viscosity fluids. However, no guarantees even with this geometry if you can get to almost zero shear rate. If you have a reasonably good rheometer, you should be able to get close though. I have used this method for a number of low viscosity non-Newtonian fluids, so I know it works. If you do not have a "rheometer", you might not be able to get very low shear rates because less sophisticated viscometers do not have the sensitivity at the lower end of the torque spectrum.

Hope this helps.

Feel free to let me know if you have any other questions and if you do try this, let me know if it worked for you.

Good luck!

You might want to consider microfluidic approaches like the mVROC by RheoSense Inc. which is suitable for low-viscosity, small-volume, high shear-rate applications.

Benson Viscometers Ltd of the UK, design, manufacture and supply clinical viscometers. they have been supplying the NHS laboratories in UK for 20 years and have analysers in Europe and USA. They have 2 types of analyser a large automated and a smaller semi automated, all with full calibration and reagent/calibration traceability.

Their website is https://www.bensonviscometers.com

you must use a rheometer, for example Anton Paar, since these are non-Newtonian fluids

Ana,

Plasma and serum act as newtonian fluids. Whole blood is non-newtonian. Therefore capillary viscometers are best for plasma/serum analsysis. Whole blood viscosity requires analysis at multiple shear values to take account of red cell aggregation

Hi Kamil

I worked as a Haematology scientist in the NHS for 40 years, and worked with several viscometers during that period. The capillary systems are much easier to use and the new generation give exceptional results in the UKs National External Quality Assesment Scheme. They cost about half the price you mentioned earlier.

The topic is quite old but as it was run again I will add two words here. I have been using few types of viscometers and rheometers. So far I could not find any which was able to measure low viscosity blood for low shear rates. It is almost impossible to get the yield stresses and especially the dynamism of the blood behaviour, etc. Fast change of the shear rates.

Since this old thread woke up, I'll add my 2 cents. As a certified grumpy old man, I can say that for blood rheology, the Contraves LS30 has never been beaten. It had a long, fine suspension wire for the bob and a rotating outer cup. This remark is totally unhelpful, unless you can find one lying around in some university's cellar. Some startup should start selling modern copies.

Kamil: For low viscosities now, my best tip is: don't try to do constant shear rate measurements. Instead, use stress-controlled instruments to measure at constant shear stress. This strategy avoids the feedback loop, which makes accurate viscosity measurements impossible at low viscosities and low shear rates, in my experience. But, there is no free lunch. You are then faced with the problems of inertia correction and the very long relaxation times to equilibrium. To save time, I used a two step protocol, giving the instrument an initial kick at above target stress to "wind it up" and then a second step at the target stress when the bob was already moving at roughly its equilibrium shear rate. I used this to make very accurate measurements of dilute sugar solutions at close to 1mPas.

To understand inertia corrections in shear stress, I think all you need is the papers by my dear departed friends Christophe Baravian and Daniel Quemada. If you are interested in thixotropy too, then you can look at the paper that the three of us published together in the obscure "Journal of Texture studies". Ask me for this one. Christophe & Daniel's work is easy to find on Google Scholar.

A final word about Daniel Quemada: before becoming a blood rheologist, he wrote a highly rated textbook on plasma (not blood plasma!) physics. He was a truly great physicist.

Dear Alan,

Thank you for your response. Mostly " grumpy people " have the most valuable advice :) I have tried this approach as well, however as I said I failed. For instance, It is stated, that torque can go down up to 1nNm. In reality, all below 100nNm was untrusted unless you need to keep unreal conditions (no wind, no vibrations, no breath...). I had a difference in data between morning and afternoon measurements with the same samples. They varied quite a lot. To have something repeatable we had to do calibration after each set of measurements. In addition, I have never gotten the yield stresses. I mean something physical. Either it was out of the range of the measurement or the yield stress for blood is something difficult to measure or observe. I know that blood is difficult to measure ( particle sedimentation, easy to change, or destroy the sample by exposing it outside the body conditions, wide range of the shear rates measurements (0-1000 1/s or even more)....) In addition, I do not know if there is an eqipment which is able to measure the fast change of the shear rates. Something similar to the body conditions, something like... the shear rates between 0-1000 1/s within 1s (heartbeat). Something more realistic I suppose...Anyway, thank you all for carrying out this discussion.

I have been worked with MCR302 Rheometer.