Succeeder SF-8100, Руководство по обслуживанию, Страница: 11 / 48

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5. Description of device
5.1. Intended Use
For in vitro Diagnostic Use Only.
SF-8100 is an automated laboratory instrument designed to perform in vitro tests which aid in the
diagnosis of coagulation abnormalities as well as to assist in monitoring anticoagulant therapy.
The instrument is capable of performing clotting assays on plasma samples.
5.2. Application
SF8100 is to measure a patient's ability to form and dissolve blood clots. To perform various
test items SF8100 use mechanical assay.
5.3. Principle of clotting method
The detection system for clotting -time assays on the SF-8100 instrument is based on the
increase of viscosity of the plasma being tested. This increase of viscosity is measured through the
motion of a stainless steel ball that is made to affect pendular swings on the two graphd rail tracks
provided in the bottom of the cuvette containing the test plasma.
Constant pendular swings of the ball are created by an electromagnetic field that is applied
alternately on opposite sides of the cuvette by two independent coils. The energy of the
electromagnetic field can be varied depending on the test being performed (weak clot for
Fibrinogen, normal clot for all the others).
Physical Principle of Measurement System
At constant plasma viscosity, ball motion remains constant.
However, as soon as the plasma starts to clot (as a result of the coagulation process being
initiated by the addition of the clot starting reagent), the viscosity of the plasma starts to increase,
and this change in plasma viscosity affects ball movement, slowing it down. As the viscosity
increases, the oscillation amplitude of the ball swing decreases. An algorithm uses these variations
in oscillation amplitude to determine the clotting time.