Efficient characterization of red blood cell rheological properties using a multichannel microfluidic chip and optical tweezers

The rheological properties of red blood cells (RBCs) are crucial for human health. Combining optical tweezers with microfluidics provides a non-contact, sensitive, and high-throughput method for studying RBC rheology. However, the limited trapping capacity of optical tweezers restricts RBC flow within microchannels, reducing individual RBC capture efficiency. To address this, we developed a multichannel microfluidic chip with a pressure relief structure. Integrating this with optical tweezers using time-division multiplexing enabled simultaneous capture of RBCs across multiple microchannels. This method not only enhances sample throughput during optical tweezer measurements but also allows individual capture and analysis of multiple flowing RBCs in the same timeframe. Image recognition analysis of RBCs captured by optical tweezers revealed distinct morphological differences between normal and diseased RBCs, consistent with finite element method simulations of RBC rheological behavior. This approach provides quantitative characterization of RBC rheology and enables effective detection. Microfluidic chip structure and multichannel erythrocyte capture. (a) Chip assembly; (b) Center capture channel of the chip; (c) Multichannel capture of erythrocytes. • Designed a multichannel optical capture microfluidic chip to address low efficiency. • Integrated a pressure relief channel into the chip to regulate flow rates in the capture channel center. • Combined the setup with image analysis to extract binarized eigenvalues of rheological images. • Measured deformation areas and lengths of erythrocytes in fluid environments. • The proposed assay efficiently quantifies changes in single erythrocyte rheological behavior.