Fibrinogen
concentration is a major determinant of both clotting
and bleeding risk. Clotting and bleeding disorders cause extensive
morbidity and mortality, particularly in resource-poor and emergency
settings. This is exacerbated by a lack of timely intervention informed
by measurement of fibrinogen levels under conditions such as thrombosis
or postpartum haemorrhage. There is an absence of simple, rapid, low-cost,
and sustainable diagnostic devices for fibrinogen measurement that
can be deployed in such environments. Paper-based analytical devices
are of significant interest due to their potential for low-cost production,
ease of use, and environmental sustainability. In this work, a device
for measuring blood plasma fibrinogen using chromatography paper was
developed. Wax printing was used to create hydrophobic structures
to define the test channel and sample application zone. Test strips
were modified with bovine thrombin. Plasma samples (22 μL) were
applied, and the flow rate was monitored over 5 min. As the sample
traversed the strip, clotting was induced by the conversion of soluble
fibrinogen to insoluble fibrin. The flow rate and distance travelled
by the sample were dependent on fibrinogen concentration. The device
was able to measure fibrinogen concentration in the range of 0.5–7.0
± 0.3 mg/mL (
p
< 0.05,
n
= 24) and had excellent correlation with laboratory coagulometry
in artificial samples (
r
2
= 0.9582,
n
= 60). Devices were also stable at 4–6 °C
for up to 3 weeks.