Carbon nanotube strain sensor based hemoretractometer for blood coagulation testing

Coagulation monitoring is essential for perioperative care and thrombosis treatment. However, existing assays for coagulation monitoring have limitations such as a large footprint and complex setup. In this work, we developed a miniaturized device for point-of-care blood coagulation testing by measuring dynamic clot retraction force development during blood clotting. In this device, a blood drop was localized between a protrusion and a flexible force-sensing beam to measure clot retraction force. The beam was featured with micropillar arrays to assist the deposition of carbon nanotube films, which served as a strain sensor to achieve label-free electrical readout of clot retraction force in real time. We characterized mechanical and electrical properties of the force-sensing beam and optimized its design. We further demonstrated that this blood coagulation monitoring device could obtain results that were consistent with those using an imaging method and that the device was capable of differentiating blood samples with different coagulation profiles. Owing to its low fabrication cost, small size, and low consumption of blood samples, the blood coagulation testing device using carbon nanotube strain sensors holds great potential as a point-of-care tool for future coagulation monitoring.