Music Box-Inspired Semi-Automatic Hematocrit Validation Device

A high hematocrit (HCT) level is strongly associated with the risk of cardiovascular disease. For early diagnosis of cardiovascular disease, it is vital to regularly measure the HCT, which is typically achieved by centrifuging a blood sample to measure the percentage of red blood cells. However, the centrifugal modalities are usually bulky, expensive, and require a stable electric input, which restrict the availability. This research develops a semi-automatic and portable centrifugal device for HCT measurement. This torque-actuated semi-automatic centrifuge, which we call the tFuge, is inspired by a music box, allowing different operators to generate the same rhythm. It is electricity-free and can be controlled based on a constant torque mechanism. Repeatable test results can be received from among different users regardless of their age, sex, and activity. With the assistance of the Boycott effect on the tFuge, we proved that the HCT level is in high linearity to the length of the sedimentation of the blood cells in a tube (R² = 0.99, sample HCT range 10-60%). The tFuge takes less than 4 min and requires no more than 10 μL of blood that can be obtained by a less-invasive finger prick to complete the testing procedure. Calibrated gradient numbers are printed onto the rotation disc for instant HCT results that can be read by the naked eye. We expect this proposed point-of-care testing device possesses the potential to replace the microhematocrit centrifuge in the regions with limited resources.