Apparatus and method for assaying coagulation in fluid samples

A cartridge adapted for use with an analyzer for assaying an enzyme in a fluid sample comprising:

• a housing having a sample entry port, overflow chamber, holding chamber, and analysis location,
• an airtight entry port closure,
• a pump actuated by the analyzer for moving the sample within the cartridge,
• one or more reagent deposits in the analysis location comprising at least one substrate capable of reaction with an enzyme in the fluid sample, the reaction of the enzyme forming a detectable reaction product,
• a first sensor for detecting the location of the fluid sample, and
• a second sensor for detecting the detectable reaction product.

A method of assaying an enzyme in a sample of blood or blood derivative, comprising the steps of:

• introducing the sample into a cartridge which includes an analysis location,
• metering a portion of the sample,
• moving the metered sample to the analysis location,
• mixing the metered sample with reagent at the analysis location,
• allowing the enzyme to react with the reagent,
• positioning the reacted sample at a sensor, and
• detecting the product of the enzyme reaction using the sensor.

A single-use cartridge used in combination with an analyzer for determining a coagulation parameter of a sample of blood or blood derivative, comprising;

• a cartridge which includes an entry port for receiving a sample, an entry port closure, a holding chamber in communication at a first end with the entry port, and a capillary stop in communication with the holding chamber at a second end, the capillary stop also in communication with an analysis chamber,
• the holding chamber in communication with an overflow chamber for receiving and retaining excess sample,
• the overflow chamber in communication with a pneumatic pump actuated by the analyzer,
• the analyzer actuating the pneumatic pump to displace sample in the holding chamber through the capillary stop into the analysis chamber to deliver a metered portion of the sample into the analysis chamber,
• the analysis chamber containing a substrate for the enzyme thrombin capable of dissolving in the metered sample, an amperometric sensor for detecting the product of the reaction between thrombin and the substrate, and a conductimetric sensor for detecting the position of the sample in the analysis chamber,
• the amperometric sensor and the conductimetric sensor connected to the analyzer for providing output signals to the analyzer,
• the analyzer capable of using the output signal of the conductimetric sensor to actuate the pneumatic pump to control the position of the sample in the analysis chamber,
• the analyzer capable of determining the coagulation parameter from the output signal of the amperometric sensor, and
• the cartridge containing a hydrophobic area between the capillary stop and the analysis chamber to prevent sample in the analysis chamber from being drawn back into the holding chamber.