Commissioning Equipment
To ascertain whether the experiment will be able to test synovial fluid accurately for ER properties it will firstly have to used on test fluids. The first test will be used to compare the results from the custom rheometer head with the rheometer head made by Thermoscientific. The second test will compare results for the custom head with a bearing friction and without bearing friction. the last test will be testing the equipment with a known ER fluid and checking that it reacts as expected.
Custom Head vs Original Head
The measurement head of the HAAKE rheometer is a precision piece with very tight tolerances. The measurement unit can bring the head accuratly to 0.01mm off the bottom plate meaning every dimension has very tight tolerances. In this experiments case the gap will be 0.5mm. As can be seen in the diagram allowing a 1% movement in the gap only gives 0.166 degrees of perfectly true which is quite tight. The new part will have to be constructed in the device manager. If the physical properties of the part are not entered correctly the measurements will not be accurate. For these reasons it is important to compare readings with the original head and possibly calibrate the custom head to the original one. With Bearing vs Without Bearing
Once the the custom head has been calibrated to the original head the effect of the bearing will have to be taken into account. This will be done by running an experiment without the bearing and then running one with the bearing. The Rheowin software has a function which allows you then to offset the torque being created by the bearing by comparing the results. Once this has been achieved the bearing should not effect the results unless its torque fluctuates greatly by which it will be taken as a source of error. ER Test It is known now that the system can measure fluids accurately with the bearing attached. It is then necessary to know whether the system can successfully pass an electric field through the liquid and measure the response. To do this a test ER fluid needs to obtained. The easiest ER fluid to make is a combination of corn starch and silicon oil. Once the apparatus can successfully measure the change in viscosity of the ER fluid it is ready to test the synovial fluid. |