PROJECT SUMMARY/ABSTRACT There are many diseases (e.g. arrhythmias, coronary artery disease, and infections) and situations (e.g. medical devices, trauma, and surgery) that require rapid and accurate point-of-care hemostatic tests, especially when regulating antithrombotics or after a blood transfusion. However, there are few options in resource-limited environments like low- and middle-income countries (LMICs), rural clinics, combat environments, and many others. This is because current hemostatic assays require electrical power, capital expense, skilled technicians, large equipment, and can be slow. As cardiovascular disease increases in LMICs, there is an urgent need to provide innovative tools for these lower resource environments. As an alternative, microfluidic-paper based analytical devices (PAD)s have been developed for low resource settings as a point-of-care technology since these are rapid, cost-effective, portable, disposable, eas-to-use, and typically require electricity. Such devices include the rapid antigen tests developed for COVID-19, which provide critical rapid feedback for making educated health decisions. These can be used almost anywhere with relatively little skill. Our goal is to develop a similar point-of-care tool that we call the Paper-based Clotting Analysis Test (P-CAT). Current PADs are limited for hemostatic analysis since they typically produce low flow conditions that can’t test many of the processes/pathways in primary hemostasis. We have developed a fast-flow PAD that will be incorporated into the P-CAT, enabling us to investigate the spectrum of pathways involved in hemostasis with only a drop (microliters) of blood. P-CATs can be created rapidly and at very little cost, thereby producing high throughput data. Here, we will develop the P-CAT to test blood samples with high specificity and and sensitivity to 1) pathways in primary (platelet-dependent) hemostasis, and 2) intrinsic and extrinsic coagulation cascades in secondary hemostasis. If successful, we will expand upon the P-CAT to incorporate additional biomarkers in an automated point-of-care device that could have a major impact on enabling portable, rapid, and inexpensive tests for hemostasis that can be widely distributed.